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Rationale: Rapid on‐site detection of persistent organic pollutants (POP) is highly desirable for environmental protection. Methods: Herein, a rapid on‐site analytical workflow was developed for the investigation of polycyclic aromatic hydrocarbons and perfluorinated compounds using multiwalled carbon nanotube–modified paper spray ionization (PSI) coupled with a miniature ion trap mass spectrometer. Critical parameters regarding PSI and miniature mass spectrometry analysis were optimized. Results: The analytical performance of the developed method was evaluated under optimized conditions, obtaining a short analysis duration of less than 1 min, sufficient linearity with correlation coefficients greater than 0.99, acceptable recovery rates of 93.1%–105.8% with relative standard deviations of between 3.5% and 10.3%, and reasonable sensitivity with limits of detection and quantitation of 2–200 and 5–500 μg/L, respectively. Conclusions: Considering these aspects, it was concluded that the present approach demonstrated a promising solution for rapid on‐site detection of emerging POPs. [ABSTRACT FROM AUTHOR]

Introduction: Distinguishing and categorizing the origin of garlic are highly significant, considering its widespread use as a flavoring agent. With billions of dollars annually in global trade, garlic is frequently susceptible to fraudulent practices. Methodology: Paper spray ionization mass spectrometry (PS‐MS) was employed to quickly analyze garlic samples from distinct geographic origins: China and Brazil. The so‐generated PS‐MS data were treated with metabolomic multivariate approaches, and the garlic samples from these different geographic regions were easily discriminated. Results: Brazilian garlic was characterized to contain higher levels of amino acids, such as arginine, proline, and valine, and organosulfur compounds, such as allicin, alliin, and l‐γ‐glutamil‐S‐allyl‐l‐cysteine, compared to Chinese garlic. The PS‐MS data were treated employing multivariate approaches, typically used in the metabolomics field, and this protocol was promptly able to discern among both types of samples. Conclusion: Hence, this combined strategy holds promise not only as an effective tool for the authentication of the geographical origin of garlic but also as a powerful means for biomarker discovery. [ABSTRACT FROM AUTHOR]

Rationale: Plasma‐based ionization sources play a vital role in rapidly analyzing diverse compounds without extensive sample pretreatment. In contrast to other sources, DC voltage‐based ionizations are more advantageous due to their high analytical sensitivity and good tandem with commercially available mass spectrometers without extra power supplies. However, their performance is at the risk of high current DC voltage and helium flow rate, which poses significant challenges to practical operation and increased expense. Methods: In this work, we propose a novel focusing plasma desorption ionization (FPDI) in which a visible plasma beam is favorably generated between a conducting wire in a polymeric tube and a counter electrode composed of metal mesh and filter paper drilled with holes. A systematic investigation has been conducted on the influences of the geometry of drilled holes in filter paper, applied DC voltage, helium flow rate, and filter paper size. The optimized system is used to analyze various pesticides in fluid foodstuffs. Results: Compared to metal mesh and conducting paper as the counter electrode for FPDI‐MS, combining metal mesh and filter paper drilled holes improved the analysis sensitivity by a factor of more than five. By applying the developed protocol for determining pesticides in complex matrixes such as orange juice and milk, a limit of detection as low as 1.3–3.0 ng mL−1 could be achieved. Conclusions: A novel FPDI‐MS technique has been developed by combining metal mesh and filter paper drilled with holes as the counter electrode and sample carrier. The corresponding improvement in analysis sensitivity facilitates the future expansion of FPDI‐MS applications into different pesticides and other compounds in complex matrixes. [ABSTRACT FROM AUTHOR]

Rationale: The burgeoning concern of N‐nitrosamine (NAM) contamination found in various pharmaceutical compositions has increased the demand for rapid and reliable screening methods to better assess the breadth of the problem. These carcinogenic compounds are also found in food, water, and soil, and they have been used in poison‐related homicides. Methods: A combination of complementary, ambient ionization methods, paper spray ionization (PSI) and filter cone spray ionization (FCSI)‐mass spectrometry (MS), was characterized towards trace‐level residue screening of select NAMs (e.g., N‐nitrosodimethylamine, N‐nitrosodiethylamine, N‐nitrosodibutylamine) directly from complex and problematic matrices of interest, including prescription and over‐the‐counter tablets, drinking water, soil, and consumable goods. Spectral data for analyte confirmation and detection limit studies were collected using a Thermo LCQ Fleet ion trap mass spectrometer. Results: PSI‐MS and FCSI‐MS readily produced mass spectral data marked by their simplicity (e.g., predominantly protonated molecular ions observed) and congruence with traditional electrospray ionization mass spectra in under 2 min. per sample. Both methods proved robust to the complex matrices tested, yielding ion signatures for target NAMs, as well as active pharmaceutical ingredients for analyzed tablets, flavorants inherent to food products, etc. Low part‐per‐million detection limits were observed but were shown dependent on sample composition. Conclusions: PSI‐MS and FCSI‐MS were successful in detecting trace‐level NAMS in complex liquid‐ and solid‐phase matrices with little to no prior preparation. This work suggests that these methodologies can provide a means for assessing problematic pharmaceutical adulterants/degradants for expedited quality control, as well as enhancing environmental stewardship efforts and forensic investigations. [ABSTRACT FROM AUTHOR]

Rationale: Paper spray (PS) is a simple and innovative ambient ionization technique for mass spectrometry (MS) analysis. Under PS‐MS conditions, chemical reactions, which usually occur slowly on a bulk scale, are accelerated. Moreover, the formation of products and transient species can be easily monitored. In this manuscript, reactions between phthalic anhydride and diamines were conducted and monitored using a PS‐MS platform. The reaction products (phthalimides) have many pharmaceutical applications, but their traditional syntheses can take hours under reflux, requiring laborious purification steps. Methods: In situ reactions were performed by dropping methanolic solutions of phthalic anhydride and diamines on a triangular paper. The analyses were achieved by positioning the triangle tip in front of the mass spectrometer entrance, whereas a metal clip was attached to the triangle base. After adding methanol to the paper, a high voltage was applied across the metal clip, and the mass spectra were acquired. Results: The intrinsic reactivity of alkyl and aromatic diamines was evaluated. The carbon chain remarkably influenced the reactivity of aliphatic diamines. For aryl diamines, the ortho isomer was the most reactive. Moreover, for aryl amines with electron‐withdrawing substituents, no reaction was noticed. Conclusions: Taking advantage of the unique characteristics of PS‐MS, it was possible to investigate the intrinsic reactivity of model alkyl (ethylene versus propylene) and aryl (o‐phenylene versus m‐phenylene and p‐phenylene) diamines towards phthalic anhydride. Some crucial parameters that affect the intrinsic reactivity of organic molecules, such as isomerism, intramolecular interaction, and conformation, were easily explored. [ABSTRACT FROM AUTHOR]

Rationale: Paper spray mass spectrometry (PS‐MS) was used to analyze and quantify ampicillin, a hydrophilic compound and frequently utilized antibiotic. Hydrophilic molecules are difficult to analyze via PS‐MS due to their strong binding affinity to paper substrates and low ionization efficiency, among other reasons. Methods: Solvent and paper parameters were optimized to increase the extraction of ampicillin from the paper substrate. After optimizing these key parameters, a Resolution IV 1/16 fractional factorial design with two center points was employed to screen eight different design parameters simultaneously. Results: Pore size, sample volume, and solvent volume were the most significant factors affecting average peak area under the curve (AUC) and the signal‐to‐blank (S/B) ratio for the 1 μg/mL ampicillin calibrant. After optimizing the key parameters, a linear calibration curve with a range of 0.2 μg/mL to 100 μg/mL was generated (R2 = 0.98) and the limit of detection (LOD) and lower limit of quantification (LLOQ) were calculated to be 0.07 μg/mL and 0.25 μg/mL, respectively. Conclusions: The statistical optimization procedure undertaken here increased the mass spectral signal intensity by more than a factor of 40. This statistical method of screening followed by optimization experiments proved faster and more efficient, and produced more drastic improvements than typical one‐factor‐at‐a‐time experiments. [ABSTRACT FROM AUTHOR]

Rationale: The effort to make fake documents look real leads to the use of crickets and beverages to produce artificially aged papers, as land titles, based on yellowing caused by the use of these methods. An old practice in Brazil, called "cricketing", has led to the misappropriation of Brazilian land using these documents. We propose a rapid, simple, instantaneous and non‐destructive method to identify artificially aged papers by easy ambient sonic‐spray ionization mass spectrometry (EASI‐MS) analysis. Methods: Three typical aging procedures were used to obtain artificially aged papers using coffee, cola drink, and crickets, with the papers being analyzed by EASI‐MS. Multivariate statistical analyses were performed on the data to find the sample groups and to study the most relevant ions of each ageing procedure. High‐resolution MS (HRMS) was used to obtain the exact masses and attribute formulae to relevant ions present in the samples. Results: The combination of EASI‐MS and multivariate statistical analyses allowed us to identify the most relevant ions to classify the adulteration of documents and HRMS identified most of these relevant ions. TMS fingerprinting in combination with multivariate analysis also demonstrated that this approach can qualitatively differentiate all the examined paper samples. Conclusions: We developed a cheap, fast and easy method that can help to elucidate counterfeit documents that have been artificially aged, helping to identify chemical additives and one that can be used in forensic laboratories. [ABSTRACT FROM AUTHOR]

Rationale The recent development of isotope ratio infrared spectroscopy (IRIS) was quickly followed by the addition of online extraction and analysis systems, making it faster and easier to measure soil and plant water isotopes. However, memory and sample size effects limit the efficiency and accuracy of these new setups. In response, this study presents a scheme dedicated to estimating and eliminating these two effects. Methods Memory effect was determined by injecting two standard waters alternately. Each standard was injected nine times in a row and analyzed using induction module cavity ring-down spectroscopy (IM-CRDS). Memory coefficients were calculated using a new 'multistage jump' algorithm. Sample size effects were evaluated by injecting water volumes ranging from 1 μL to 6 μL. Finally, the influence of cellulose filter paper on the isotopic measurements, the memory, and the sample size effect was evaluated by comparing it with glass filter paper. Results Memory effects were detected for both δ18O and δ2H values, with the latter being stronger. Isotopic differences between replicates of the same plant or soil sample showed a clear decrease after memory correction. A small water volume effect was found only when the injected water volume was larger than 3 μL. However, while the correction method performed well for laboratory-made samples, it did not for field samples, due to the heterogeneity of the isotopic composition of the samples. Stronger memory and water volume effects were found for cellulose filter paper. Conclusions The memory coefficients and the water volume-isotope relationship improved the consistency and accuracy of both laboratory and field data. Our results indicate that cellulose filter paper may not be a suitable medium to measure standard waters and evaluate memory and water volume effects. Finally, a detailed correction and calibration protocol is suggested, along with notes on best practices to obtain good-quality IM-CRDS data. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Rationale: Paper spray offers a rapid screening test without the need for sample preparation. The incomplete extraction of paper spray allows for further testing using more robust, selective and sensitive techniques such as liquid chromatography/mass spectrometry (LC/MS). Here we develop a two‐step process of paper spray followed by LC/MS to (1) rapidly screen a large number of samples and (2) confirm any disputed results. This demonstrates the applicability for testing medication adherence from a fingerprint. Methods: Following paper spray analysis, drugs of abuse samples were analysed using LC/MS. All analyses were completed using a Q Exactive™ Plus Orbitrap™ mass spectrometer. This two‐step procedure was applied to fingerprints collected from patients on a maintained dose of the antipsychotic drug quetiapine. Results: The extraction efficiency of paper spray for two drugs of abuse and metabolites was found to be between 15 and 35% (analyte dependent). For short acquisition times, the extraction efficiency was found to vary between replicates by less than 30%, enabling subsequent analysis by LC/MS. This two‐step process was then applied to fingerprints collected from two patients taking the antipsychotic drug quetiapine, which demonstrates how a negative screening result from paper spray can be resolved using LC/MS. Conclusions: We have shown for the first time the sequential analysis of the same sample using paper spray and LC/MS, as well as the detection of an antipsychotic drug from a fingerprint. We propose that this workflow may also be applied to any type of sample compatible with paper spray, and will be especially convenient where only one sample is available for analysis. [ABSTRACT FROM AUTHOR]

Rationale: Accurate measurement of trace compounds in blood samples is important in clinical diagnosis and life science. Ambient ionization mass spectrometry, however, suffers from the matrix effect when dealing with complex samples such as blood. Therefore, it is important to reduce the matrix effects in blood samples. Methods: A low-cost and disposable Teflon tube was used as a platform to precipitate the protein in blood. The analytes are extracted into organic solvent, and the precipitated protein can be adsorbed by the chromatography paper inserted. Therefore, the Teflon tube after precipitation can be directly subjected to paper spray ionization mass spectrometry, achieving one-step analysis of blood. Results: High sensitivity and satisfactory stability were achieved for pharmaceuticals, acids, and endogenic metabolites in blood. The absolute signal intensities of characteristic product ions of the tested analytes were 8–20 times higher after protein precipitation than those obtained using paper spray. Detection limits and quantitative performance were evaluated for three drugs: carbamazepine, metformin, and tioconazole. In addition, the limits of detection and quantitation were improved 9–14- and 8–12-fold, respectively. Conclusions: Protein precipitation coupled to paper spray with a tube and then to mass spectrometry was successfully achieved and applied in the one-step analysis of trace compounds in blood samples. The experimental results showed that this method was sensitive, stable, convenient, and economic for the direct analysis of blood. [ABSTRACT FROM AUTHOR]

Rationale: The analysis of chemical warfare agents (CWAs) from ambient atmosphere presents an analytical challenge due to their ease of degradation and volatility. Herein is described a method for derivatizing CWAs directly onto a paper spray substrate prior to analysis. This derivatization allows for much longer times of analysis without sample degradation and with little to no sample preparation. Methods: Derivatization was performed using 2‐[(dimethylamino)methyl] phenol both in‐vial and directly on paper spray cartridges. Solution studies were carried out over time and samples were analyzed via liquid chromatography/tandem mass spectrometry (LC/MS/MS) operated in positive ion mode. Paper spray substrates impregnated with the derivatizing agent prior to CWA vapor capture were also analyzed over time using a mass spectrometer operated in positive ion mode. Results: Use of 2‐[(dimethylamino)methyl] phenol as a paper spray substrate dopant enables derivatization of G‐series compounds into lower volatility complexes. The reaction occurs in solution and in the vapor phase. This new technique effectively traps and captures G‐series agents for analysis while extending the time for which the compound remains absorbed. The complex is highly suitable for direct analysis via paper spray mass spectrometry. Conclusions: Derivatization of paper spray substrates was shown to greatly increase the time for analysis of CWAs. This technique, combined with the vapor phase capture stage outlined previously, allows for rapid, quantitative CWA detection by paper spray ionization with little or no sample preparation. [ABSTRACT FROM AUTHOR]

Rationale: The loquat (Eriobotrya japonica Lindl.) is a fruit tree that has been used in Chinese medicine for thousands of years for the treatment of various diseases. The loquat leaf extracts contain several bioactive compounds with antioxidant and antimicrobial properties, and identification of these substances using quick and simple methods has been an analytical trend. Methods: The influence of dehydration of loquat leaves (without drying, at 40_C, and at 60_C), the type of solvent (ethanol and methanol), and the method of extraction (shaking and ultrasound) on obtaining extracts containing phenolic compounds and substances with antioxidant and antimicrobial properties was evaluated. The chemical constituents of an extract were identified using paper spray mass spectrometry (PS-MS). Results: The extract obtained from the dehydrated leaves at 40_C presented the best results. The extracts obtained from these leaves and with ethanol had the highest values of total phenolics and antioxidant activities, but the methanolic extract subjected to ultrasound had the highest levels of chlorogenic, caffeic, and ellagic acids. All extracts evaluated inhibited the growth of Staphylococcus aureus. Using the PS-MS technique, it was possible to identify the presence of 49 substances such as organic acids, phenolic acids, flavonoids, sugars, quinones, and terpenes. Conclusions: In general, extracts of dehydrated leaves at 40_C and extracted with ethanol using ultrasound can be considered a good source of bioactive compounds with potential applications as functional ingredients or additives in the food and pharmaceutical industries. PS-MS was demonstrated to be a simple and ultrafast technique to obtain the chemical profile of the loquat leaf extract. [ABSTRACT FROM AUTHOR]

Rationale: Smoking is responsible for one in five deaths around the world. Thus, governments have been trying to reduce the number of active smokers by increasing taxes on products. This scenario creates a new problem by raising the consumption of illegally traded cigarettes, which are often seized and analyzed by police forces. Methods: Legal and illegal cigarette samples were extracted and analyzed using paper spray ionization mass spectrometry (PS-MS). The mass spectrometer was set to operate in full-scan positive ion mode to yield representative chemical profiles of each sample. The results were used to build a chemometric model using partial least squares discriminant analysis (PLS-DA) to discriminate between both sets of samples, i.e. legal and illegal. Results: The PS-MS procedure was fast, simple and efficient, yielding high-quality and reproducible mass spectra with a very good signal-to-noise ratio. Even though all samples displayed visually indistinguishable mass spectra, the PS-MS data handled by the PLS-DA approach furnished a model that reached sample classification with rates of 100% and 80% for the training and validation sets, respectively. Conclusions: A novel methodology was successfully developed associating the PSMS technique with chemometric analysis to differentiate between legal and illegal cigarettes. The PS-MS technique proved to be adequate for obtaining fingerprints of such types of samples despite high complexity, and a PLS-DA model was successfully constructed achieving 82.1% accuracy. [ABSTRACT FROM AUTHOR]

Rationale: The ability to detect and quantify the presence of specific inorganic elements and complexes is essential for environmental monitoring and nuclear safeguards applications. In this work, paper spray ionization mass spectrometry was used for the rapid chemical and isotopic characterization of trace inorganic species collected on cotton swipe substrates. The direct analysis of cotton swipes using this ambient ionization technique led to fast sample analysis that retained original chemical information of the source material with minimal sample preparation. Methods: Mass spectra were collected with an atmospheric pressure ionization, high‐resolution mass spectrometer for solutions containing uranyl acetate, uranyl chloride, uranyl nitrate, and uranyl tri‐n‐butylphosphate complexes. Gadolinium nitrate was used as an internal standard for the quantitative analysis of uranium. To demonstrate the ability to characterize inorganic contaminants in the presence of uranium, a multi‐element inorganic standard containing U, Bi, Pb, Cd, Fe, and Zn was deposited onto cotton substrates and directly analyzed without purification. Results: All elements doped on the cotton substrate were detected with strong signal‐to‐noise ratios (ca 1000 for UO2+ on multi‐element doped swipes) and high integrated intensities (>105 counts) from collection periods of approximately 1 min. Limits of detection were determined to be approximately 94 ng for UO2+ and uranyl acetate through the measurement of ppb level solutions. Conclusions: The rapid analysis of uranium and other inorganic‐containing samples while still retaining original chemical information (e.g. uranyl complexation) was demonstrated. Qualitative detection and speciation were achieved in less than 1 min of analysis. For uranium isotopic quantitation, longer accumulations (>15 min) can be sustained to improve the accuracy of minor 235U isotopic abundance measurements to approximately 1% error. [ABSTRACT FROM AUTHOR]

Rationale Zero volt paper spray ionization (zvPSI) is a newly developed sample introduction/ionization technique for mass spectrometry (MS), which combines favorable features of paper spray ionization (PSI) and solvent-assisted inlet ionization (SAII). With a simple platform similar to PSI, zvPSI allows direct MS analysis of a broad type of samples (liquid, (semi-)solid, and imprint) without applying voltage. Methods In zvPSI-MS, a rectangular paper slip was used as a sample loader, extraction medium, and droplet emitter to introduce sample extract into the inlet of a mass spectrometer. For (semi-)solid and imprint samples, analyte(s) was directly extracted with solvent and instantaneously introduced into a mass spectrometer by aspiration. Solution samples were analyzed after being dried-up or by dispensing directly onto paper. Ionization was achieved by SAII and ionized molecules were detected by an ion-trap mass spectrometer. Results The developed method allowed direct voltage-free MS analysis of samples on filter paper substrate. Favorable features of PSI and SAII were successfully combined, such as fast data acquisition, flexible sample handlings, and direct extraction capability from solid samples (PSI), with no need for external high-voltage, laser, or nebulizing gas to convert analytes into gas-phase ions (SAII). Comparable to PSI and SAII, a wide variety of compounds such as amino acids, peptides, lipids and synthetic polymers were shown to be analyzed. Conclusions The developed method (zvPSI-MS) expanded the analytical utility of PSI and SAII to voltage-free direct MS analysis of a broad type of samples (liquid, (semi-)solid, and imprint). Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Rationale Significant advances have been made in the preparation of different morphologies of magnesium oxide (MgO), but the relationship between MgO morphology and its interactions with therapeutic drugs is rarely studied. Herein, we investigated the interactions between different morphologies of MgO and therapeutic drugs using paper spray mass spectrometry. Methods Different morphologies of MgO including trapezoidal, needle-like, flower-like and nest-like structures were prepared through a facile precipitation method. The as-obtained MgO particles were then coated onto the surface of filter paper via vacuum filtration strategy. The coated papers with different morphologies of MgO were used as the substrates for paper spray mass spectrometry to explore the interactions between different MgO and therapeutic drugs. Results Through investigating the interactions between different morphologies of MgO coated papers and therapeutic drugs, it demonstrated that, in contrast to the trapezoidal, needle-like and nest-like MgO coated papers, different drugs in dried blood spots (DBS) were more favourably eluted off from the paper coated with flower-like MgO due to its weaker surface basicity. Also, the signal intensities of different drugs during paper spray were highly dependent on their elution behaviours. Conclusions Paper spray mass spectrometry (MS) provides an avenue to elaborate the surface properties of MgO with different structures. The surface basicity of MgO played a crucial role in determining the elution behaviours of therapeutic drugs in DBS, and a more favourable elution behaviour tended to result in a higher MS signal. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Rationale: A reactive paper spray mass spectrometric approach for rapid analysis of formaldehyde (FA) in cosmetics was developed based on an on‐line derivatization reaction between formaldehyde and dansyl hydrazine (DH). Methods: The whole experimental procedure consists of three simple steps: (1) load the sample (2 μL) onto the paper; (2) add the spray solvent (10 μL DH); (3) apply a high voltage (+4.5 kV) to the sample. We used an internal standard (dansyl amide) to create the analytical calibration curve. The established approach has been successfully applied in the quantitation of FA in facial masks. Results: Our approach shows good linearity for the FA concentrations between 3 and 300 μg L−1, and the limit of detection is at 0.8 μg L−1. Five brands of facial masks were analyzed by this approach without any sample pretreatment, and the FA contents varied from 0.05 to 2.6 mg L−1 with favorable recoveries achieved between 93.2% and 111.3%. Conclusions: This established approach presents a solution to rapid quantitation at extremely low cost of consumables and has potential as a simple, sensitive and robust strategy for the direct analysis of FA in cosmetics, food, environmental, and biological samples. [ABSTRACT FROM AUTHOR]

Rationale: Paper spray (PS) has been developed as a method of choice for point‐of‐care analysis in many real cases, where its applications can be further expanded with delicate high‐throughput design. To achieve this goal, we developed a new PS regime, with the assembly of an induced high voltage into the ion source. Compared with regular DC high voltage, the newly developed setup is capable of high‐throughput, simple configuration and rapid switching between individual papers without complicated electric/mechanic design. Methods: A device of high‐throughput induced PS (IPS) was designed by using a two‐dimensional (2D) rotating platform equipped with a circular glass plate. The paper substrate was placed on the circular glass plate and separated from the electrode. The method avoids physical contact between the electrode and the sample. Charged droplets were generated at the paper tip once an induced high voltage was applied to a wet paper. Results: A relatively rapid analytical speed of 2.6 s per sample was achieved via IPS‐MS. Rapid quantification of amitriptyline (AMT) in complicated matrices was obtained within 1 min using an isotope internal standard method. Limits of detection for AMt in urine, FBS and blood were calculated to be 1.04, 0.84 and 1.33 ng/mL, respectively. In addition, high‐throughput IPS‐MS can be used for chemical reaction monitoring. Conclusions: We have demonstrated the versatility of high‐throughput IPS‐MS in ambient ionization, which successfully simplified the experimental installation and facilitated the experimental operation. Therefore, we believe that high‐throughput IPS‐MS analysis will be widely used for discovering drugs and screening reactions, and the present design has the potential for applications in paper chip‐MS analysis. [ABSTRACT FROM AUTHOR]

Rationale: The decolouration of brilliant blue FCF by the action of titanium dioxide (TiO2) under ultraviolet (UV) exposure has been recently reported as the basis of a paper‐based sensor for monitoring UV sun exposure. The mechanism of brilliant blue FCF photodegradation in the presence of the photocatalyst and the resulting photoproducts are thus far unknown. Methods: The UV‐initiated photodegradation of brilliant blue FCF in the presence of TiO2 for both the aqueous and the solid state was investigated. Degradation in the solid state was observed using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐MS). Decomposition of the dye in the aqueous state was analyzed using liquid chromatography/mass spectrometry (LC/MS) and ultraviolet–visible (UV–Vis) spectroscopy. Results: After UV radiation exposure, the brilliant blue FCF base peak [M1 + NH4]+ (m/z calc. 766.194 found 766.194) decreased in the LC/MS chromatogram with a concomitant appearance of BB‐FCF decomposition products involving the sequential loss of the N‐ethyl and N‐methylbenzene sulfonate (MBSA) groups, assigned as [M2 + H]+ (‐MBSA, calc. 579.163 found 579.162), [M3 + H]+ (‐MBSA, −Et, calc. 551.131 found 551.131), [M4 + H]+ (‐2MBSA, calc. 409.158 found 409.158), [M5 + H]+ (‐2MBSA, −Et, calc. 381.127 found 381.127). Ions [M2 + H]+ and [M3 + H]+ were also identified in the photodegradation products using MALDI‐MS. Observation by UV–Vis indicated a decrease in the solution absorbance maxima and an associated blue‐shift upon UV exposure in solution. Conclusions: The LC/MS analysis indicated two main oxidation processes. The most obvious was attack of the N‐methylene, eliminating either ethyl or MBSA groups. The presence of the hydroxylated decomposition product M13 ([M13 + H]+, calc. 595.157 found 595.157) supported this assignment. In addition, the detection of photoproduct M8, proposed to be 3‐((ethylamino)methyl)benzenesulfonic acid ([M8 + H]+, calc. 216.069 found 216.069), indicates an aryl‐oxidative elimination. The absence of the aryl‐hydroxy products normally expected to accompany the formation of M8 is proposed to be due to TiO2‐binding catechol‐like derivatives, which are then removed upon filtration. [ABSTRACT FROM AUTHOR]

Rationale: Drug overdose deaths due to fentanyls and other novel psychoactive substances (NPS) are on the rise. The higher potencies of fentanyl analogs compared with morphine require new technologies to identify and quantitate NPS. Methods: Paper spray tandem mass spectrometry (MS/MS) and high‐resolution mass spectrometry were used to identify and measure fentanyl analogs as well as common drugs of abuse in urine samples from substance use disorder clinics. Ten‐microliter urine samples were deposited directly on paper spray cartridges previously loaded with internal standards, dried, and analyzed with no other sample treatment. Quantitative results were obtained using MS/MS. Individual drugs were identified using high‐resolution accurate mass spectrometry, and confirmed by data‐dependent MS/MS. Results: Calibration curves in urine were linear over a range of 0.5–50 ng/mL with R2 of 0.99 or better for eight representative fentanyl analogs. Cartridges preloaded with internal standards demonstrated satisfactory quantitative results compared with LC/MS. Direct identification and confirmation of fentanyl analogs and other common drugs of abuse in urine using high‐resolution accurate mass and MS/MS fragmentation were demonstrated at low picogram levels. Conclusions: Paper spray mass spectrometry can reliably identify and quantitate fentanyl analogs and other drugs of abuse in urine. Using paper spray cartridges as collection devices reduces exposure and transportation risks associated with biological fluids. Cartridges preloaded with labeled internal standards can be effective for targeted screening of fentanyl analogs and other drugs of abuse. [ABSTRACT FROM AUTHOR]

Rationale: Paper spray ionization (PSI) is an attractive ambient ionization source for mass spectrometry (MS) since it allows the combination of surface sampling and ionization. The minimal sample preparation inherent in this approach greatly reduces the time needed for analysis. However, the ions generated from interfering compounds in the sample and the paper substrate may interfere with the analyte ions. Therefore, the integration of PSI with high‐field asymmetric ion mobility spectrometry (FAIMS) is of significant interest since it should reduce the background ions entering the mass analyzer without complicating the analysis or increasing analysis time. Here we demonstrate the integration of PSI with FAIMS/MS and its potential for analysis of samples of forensic interest. Methods: In this work, the parameters that can influence the integration, including sampling and ionization by paper spray, the FAIMS separation of analytes from each other and background interferences, and the length of time that a usable signal can be observed for explosives on paper, were evaluated with the integrated system. Results: In the negative ion analysis of 2,4,6‐trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX), and 1,3,5‐trinitroperhydro‐1,3,5‐ triazine (RDX), amounts as low as 1 ng on paper were readily observed. The successful positive ion separation of a set of illicit drugs including heroin, methamphetamine, and cocaine was also achieved. In addition, the positive ion analysis of the chemical warfare agent simulants dimethyl methylphosphonate (DMMP) and diisopropyl methylphosphonate (DIMP) was evaluated. Conclusions: The integration of PSI‐FAIMS/MS was demonstrated for the analyses of explosives in negative ion mode and for illicit drugs and CW simulants in positive mode. Paper background ions that could interfere with these analyses were separated by FAIMS. The compensation voltage of an ion obtained by FAIMS provided an additional identification parameter to be combined with the mass spectrum for each analyte. [ABSTRACT FROM AUTHOR]

Rationale Human health concerns have arisen for common bisphenols (BPA and BPS) as well as new structural analogs. While native sulfone bisphenols and sulfone-derivatized bisphenols are amenable to electrospray ionization (ESI), alternative ionization methods such as atmospheric pressure chemical ionization (APCI) and APPI were investigated to analyze non-derivatized, non-sulfone-containing bisphenols. Methods Ionization of bisphenols using negative ion APPI was compared to negative ion ESI and negative ion APCI for their relative abilities to produce [M−H]− precursor ions for subsequent collision-induced dissociation (CID) in a triple quadrupole mass analyzer. Multiple reaction monitoring (MRM) transitions were optimized using the most sensitive ion transitions and coupled with high-performance liquid chromatographic (HPLC) separation to detect and quantify BPA, BPB, BPF, BPZ, BPAP, BPS, and BPSIP. Results APPI provides a more universal sensitivity over ESI toward the classes of bisphenols studied with detection limits of 20-50 pg on-column. The LC/APPI-MS/MS method was used to examine the levels of these seven bisphenols in thermal paper receipts and in U.S. paper currency. In both receipts and currency, BPA and BPS were the dominant bisphenols found in the paper. Conclusions The measurement of BPA and bisphenol analogs in thermal paper receipts and transfer of bisphenols from receipts to currency notes is of increasing importance to assess human dermal exposure routes to this class of compounds. Equivalent sensitivity between sulfone- and non-sulfone-containing bisphenols is achievable through the use of alternate ionization sources such as APCI and APPI that circumvents tedious and time-consuming derivatization procedures to render analytical sensitivity by ESI. [ABSTRACT FROM AUTHOR]

Rationale A desired feature in the analysis of explosives is to decrease the time of the entire analysis procedure, including sampling. A recently utilized ambient ionization technique, paper spray ionization (PSI), provides the possibility of combining sampling and ionization. However, an interesting phenomenon that occurs in generating negatively charged ions pose some challenges in applying PSI to explosives analysis. The goal of this work is to investigate the possible solutions for generating explosives ions in negative mode PSI. Methods The analysis of 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) was performed. Several solvent systems with different surface tensions and additives were compared to determine their effect on the ionization of explosives. The solvents tested include tert-butanol, isopropanol, methanol, and acetonitrile. The additives tested were carbon tetrachloride and ammonium nitrate. Results Of the solvents tested, isopropanol yielded the best results. In addition, adding ammonium nitrate to the isopropanol enhanced the analyte signal. Experimentally determined limits of detection (LODs) as low as 0.06 ng for PETN, on paper, were observed with isopropanol and the addition of 0.4 mM ammonium nitrate as the spray solution. In addition, the explosive components of two plastic explosive samples, Composition 4 and Semtex, were successfully analyzed via surface sampling when using the developed method. Conclusions The analysis of explosives using PSI-MS in negative ion mode was achieved. The addition of ammonium nitrate to isopropanol, in general, enhanced the analyte signal and yielded better ionization stability. Real-world explosive samples were analyzed, which demonstrates one of the potential applications of PSI-MS analysis. [ABSTRACT FROM AUTHOR]

RATIONALE The polycyclic aromatic hydrocarbons quinones are reported to be harmful and could cause mutations and cancer via the generation of reactive oxygen species through their redox cycle in human body. For detection by gas chromatography and high-performance liquid chromatography mass spectrometry (MS), sample pretreatments and chromatographic separation prior to MS are generally required, which makes the whole analytical process laborious and time-consuming, resulting in difficulties for fast screening targets from complicated matrices. Thus facile, rapid and reliable MS methods for detection of quinones in complicated matrices are in great demand. METHODS Reactive paper spray mass spectrometry is reported for rapid identification and quantification of quinones in complicated matrices. The method is based on an in situ derivatization reaction between cysteamine and quinones prior to analysis with paper spray mass spectrometry. With the addition of an easily charged chemical tag, the ionization efficiency of analysts is greatly improved. Due to the high ionization efficiency of the drivatives, quinones in complicated matrices could be detected rapidly without any pretreatment. RESULTS Under the optimized experimental conditions, the linear dynamic ranges for both 1,4-benzoquinone and 1,4-naphthoquinone are 0.4-40 ng and that for 1,4-anthraquinone is 0.4-20 ng. Limits of detection for these three analytes were measured to be 160, 40 and 200 pg using methyl- p-benzoquinone as internal standard. The capability to conduct MS analysis under ambient pressure is illustrated by identification of 1,4-naphthoquinone and 1,4-anthraquinone in raw urine, raw serum and cell culture medium. CONCLUSIONS Reactive paper spray could be applied to fast screening of quinones from complicated matrices. Therefore, we believe that reactive paper spray mass spectrometry might be potentially useful in the fields of environmental sciences, metabolomics and clinic analysis. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

RATIONALE: Despite ample research into the atmospheric oxidation of α-pinene, an important precursor to biogenic secondary organic aerosol formation, the identification of its reaction products, specifically organic nitrates, which impact atmospheric NOx concentrations, is still incomplete. This negatively impacts our understanding of α-pinene oxidation chemistry and its relation to air quality. METHODS: Photochemical chamber experiments were conducted in conjunction with mass spectrometric techniques, including gas chromatography/mass spectrometry (GC/MS), high-performance liquid chromatography/time-of-flight (HPLC/TOF), and paper spray ionization MS, to investigate products from the OH radical initiated oxidation of α-pinene under high NOx conditions. RESULTS: Over 30 compounds were tentatively identified, including those newly detected from photochemical chamber studies of α-pinene oxidation, pinocamphenol, fencholenic aldehyde, and α-pinene-derived nitrate isomers. α-Pinene-derived hydroxynitrate isomers were successfully detected using chromatographic methods, demonstrating, for the first time, the identification of individual first-generation organic nitrate products derived from α-pinene. The application of paper spray ionization to particle-phase compounds collected on filters represents a novel method for the direct analysis of filter samples at ambient pressure and temperature. CONCLUSIONS: The use of HPLC/TOF and paper spray ionization methods to identify previously unobserved α-pinene-derived products helps lower the uncertainty in α-pinene oxidation chemistry and provides new platforms that can be used to identify and quantify important atmospheric compounds that relate to air quality in a complex sample matrix, such as ambient aerosol particles. Additionally, the use of paper spray ionization for direct filter analysis is a fast, relatively inexpensive sample preparation technique that can be used to reduce sample manipulation from solvent-induced reactions. [ABSTRACT FROM AUTHOR]

RATIONALE: The monitoring of chemical systems in dynamic equilibrium is not an easy task. This is due to the high rate at which the system returns to equilibrium after being perturbed, which hampers the possibility of following the aftereffects of the disturbance. In this context, it is necessary to use a fast analytical technique that requires no (or minimal) sample preparation, and which is capable of monitoring the species constituting the system in equilibrium. Paper spray ionization mass spectrometry (PS-MS), a recently introduced ambient ionization technique, has such characteristics and hence was chosen for monitoring a model system: the redox process of methylene blue. METHODS: The model system evaluated herein was composed of three cationic species of methylene blue (MB), which coexist in a dynamic redox system: (1) [MB]+ of m/z 284 (cationic MB); (2) [MB + H + e]+⋅ of m/z 285 (the protonated form of a transient species resulting from the reduction of [MB]+); (3) [MB + 2H + 2e]+ or [leuco-MB + H] + of m/z 286 (the protonated leuco form of MB). Aliquots of a MB solution were collected before and after the addition of a reducing agent (metallic zinc) and directly analyzed by PS-MS for identification of the predominant cationic species at different conditions. RESULTS: The mass spectra revealed that before the addition of the reducing agent the ion of m/z 284 (cationic MB) is the unique species. Upon the addition of the reducing agent and acid, however, the solution continuously undergo discoloration while reduced species derived directly from cationic MB (m/z 285 and 286) are detected in the mass spectra with increasing intensities. Fragmentation patterns obtained for each ionic species, i.e. [MB]+, [MB+H+e] +⋅ and [leuco-MB+H]+, shown to be consistent with the proposed structures. CONCLUSIONS: The PS-MS technique proved to be suitable for an in situ and 'near' real-time analysis of the dynamic equilibrium involving the redox of MB in aqueous medium. The data clearly demonstrated how the redox equilibrium shifts depending on the disturbance caused to the system. [ABSTRACT FROM AUTHOR]

Rationale High-throughput screening of biofluids is essential in monitoring concentration of a variety of drugs to determine their efficacy and toxicity. Organosiloxane polymers prepared by sol-gel chemistry as sample supports, and electrospray ionization emitters in a single material and as an alternative to paper substrates, is described in this study. Methods Hydrophobic drugs and hydrophilic streptomycin were analyzed by polymer-spray mass spectrometry with an LTQ-Orbitrap mass spectrometer. Drug samples in urine (1-2 μL) were deposited on an OSX polymer, allowed to dry, then electrosprayed from the polymer tip into the mass spectrometer without sample pretreatment. The OSX polymers, whose polarity and porosity can be controlled, were prepared by sol-gel chemistry where methyl-substituted alkoxysilanes were hydrolyzed in the presence of a pore template and an acid catalyst. Results Five nanograms each of seven narcotic drugs were detected in <1 min (relative standard deviation (RSD) of response <1% for each drug). Calibration curves of cocaine and streptomycin in urine were used to establish the performance of the polymer. For sample 1 (n = 2), the mean recovery for cocaine was 81% with paper and 90% with polymer. Streptomycin is detected with polymer, not with paper; for samples 1 and 2 (n = 3), mean recovery was 97% and 95%, respectively. Conclusions Organosiloxane polymers achieve more sensitive analysis than paper, allowing for more accurate quantitation of both hydrophobic and hydrophilic drug compounds. The ability to tailor the polymer polarity and porosity allows for the synthesis of a wide range of polymers, and thus opens many possibilities for further development and applications. [ABSTRACT FROM AUTHOR]

Rationale: Ambient mass spectrometry techniques are much required in forensic chemistry to evaluate evidence with low analytical interference, high confidence, and accuracy. However, traditional methodologies, such as paper spray ionization, have been shown to present low sensitivity in the analysis of illicit drugs from biological matrices. Methods: Fiber spray ionization mass spectrometry (FSI‐MS) was developed using a capillary polypropylene (PP) hollow fiber. Seized samples of drugs, i.e. a tablet, blotter paper, hashish, and cocaine powder, were analyzed. Cocaine was quantified from whole urine by dipping the fiber directly into solution. FSI‐MS was tested for the analysis of a sample of urine obtained from a drug abuse suspect. Results: The FSI(+) analysis showed the detection of different types of synthetic drugs in tablet and blotter paper samples, e.g. amphetamine, cathinones, phenethylamines, and opioids, while pure cocaine and different types of coca alkaloids were identified from cocaine powder with good sensitivity and high mass accuracy. The hashish analysis by FSI(−) revealed signals of cannabinoids, cannabinoid acids, and cannabinoid derivatives, detected mainly as [M − H]− ions or chlorine adducts [M + Cl]−. The quantification of cocaine in whole urine showed good sensitivity and precision with limits of detection and quantification of 5.16 and 17.21 ng/mL, respectively, linearity above 0.999, and relative standard deviation below 2.71%. The evaluation of seized sample of urine showed the detection of cocaine with relative ion intensity greater than 36%, as well as the metabolites benzoylecgonine and cocaethylene with a relative intensity of 1.4% and 6%, respectively. Conclusions: The developed FSI‐MS method has the potential to be applied to forensic sample evaluation as well as to determine illicit drugs from biological matrices in toxicological analysis. The use of a capillary PP fiber has advantages as an extractor agent and ionizing substrate, and also the feature of it being dipped directly into the sample, thus preserving the integrity of the sample, which makes this a very promising ambient mass spectrometry method and relevant to forensic chemistry. [ABSTRACT FROM AUTHOR]

Rationale: Chlorinated aromatics and alkanes are widely used for their flame retardancy, but they need to be monitored when used in recycled pulp. This paper reports the use of palladium acetate/activated carbon (Pa/Ac) activated by nitric acid as an online catalyst to determine chlorinated aromatics and chlorinated alkanes in recycled paper products using gas chromatography–tandem mass spectrometry (GC–MS/MS), which significantly improves the sensitivity of the method and remarkably lowers the detection limits. Methods: The Pa/Ac catalyst was prepared using a self‐made catalytic device and used as key to the online catalytic conversion of target chlorinated aromatic hydrocarbons and chlorinated alkanes for GC–MS/MS analysis. The response surface model was used to optimize catalytic conditions. Then GC–MS/MS in the multireaction monitoring mode with online catalysis was applied for the analysis of polychlorinated biphenyls, polychlorinated terphenyls, polychlorinated naphthalene, and chlorinated paraffins (CP) in recycled paper products. Results: Compared with traditional methods, the Pa/Ac catalyst can transform chlorinated aromatic hydrocarbons into aromatic hydrocarbons through dechlorination hydrogenation, thus lowering the detection limit of the GC–MS/MS method significantly. It can transform paraffin chloride into the corresponding alkane to better distinguish short‐chain, medium‐chain, or long‐chain CPs. Online catalytic conversion significantly improved the sensitivity and reproducibility (88.7%–113.1%) of the method. Tissue samples with various concentration levels of chlorinated aromatics and chlorinated alkanes were tested. The linearity range of the reduced target compounds in the reduction product solution was 0.02–1.00 μg/ml (R2 > 0.995). The quantitative detection limit was 0.03–0.05 μg/kg, and relative standard deviation was less than 6.9%. Conclusion: This study was the first to introduce the Pa/Ac catalytic device as an online catalytic unit in the determination of chlorinated aromatics and chlorinated alkanes using the GC–MS/MS method. The target compounds were converted into alkanes and aromatic hydrocarbons with unchanged carbon structures, and the method could achieve a low detection limit with no need for high‐end methods such as GC‐chemical ionization ion source (CI)‐MS or high‐resolution mass spectrometry. These methods are suitable for the determination of chlorine pollutants in recycled paper and its raw materials. [ABSTRACT FROM AUTHOR]

RATIONALE: With the current state-of-the-art detection of ions only taking place under vacuum conditions, active pixel detectors that operate under ambient conditions are of particular interest. These detectors are ideally suited to study and characterize the charge distributions generated by ambient ionization sources. METHODS: The direct imaging capabilities of the active pixel detector are used to investigate the spatial distributions of charged droplets generated by three ionization sources, named electrospray ionization (ESI), paper spray ionization (PSI) and surface acoustic wave nebulization (SAWN). The ionization spray (ESI/PSI) and ionization plume (SAWN) originating from each source are directly imaged. The effect of source parameters such as spray voltage for ESI and PSI, and the angle of the paper spray tip on the charge distributions, is investigated. Two types of SAWN liquid interface, progressive wave (PW) and standing wave (SW), are studied. RESULTS: Direct charge detection under ambient conditions is demonstrated using an active pixel detector. Direct charge distributions are obtained of weak, homogeneous/focused and dispersed spray plumes by applying low, intermediate and high spray potentials, respectively, for ESI. Spray plume footprints obtained for various angles of PSI shows the possibility to focus the ion beam as a function of the paper angle. Differences between two designs of the SAWN interface are determined. Droplet charge flux changes are illustrated in a way similar to a total ion chromatogram. CONCLUSIONS: The use of this active pixel detector allows the rapid characterization and optimization of different ambient ionization sources without the actual use of a mass spectrometer. Valuable illustrations are obtained of changes in spatial distribution and number of charges detected for ESI, PSI and SAWN ion plumes. [ABSTRACT FROM AUTHOR]

Rationale: The level of visual detail of a mass spectrometry image is dependent on the spatial resolution with which it is acquired, which is largely determined by the focal diameter in infrared laser ablation‐based techniques. While the use of mid‐IR light for mass spectrometry imaging (MSI) has advantages, it results in a relatively large focal diameter and spatial resolution. The continual advancement of infrared matrix‐assisted electrospray ionization (IR‐MALDESI) for MSI warranted novel methods to decrease laser ablation areas and thus improve spatial resolution. Methods: In this work, a Schwarzschild‐like reflective objective was incorporated into the novel NextGen IR‐MALDESI source and characterized on both burn paper and mammalian tissue using an ice matrix. Ablation areas, mass spectra, and annotations obtained using the objective were compared against the current optical train on the NextGen system without modification. Results: The effective resolution was determined to be 55 μm by decreasing the step size until oversampling was observed. Use of the objective improved the spatial resolution by a factor of three as compared against the focus lens. Conclusions: A Schwarzschild‐like reflective objective was successfully incorporated into the NextGen source and characterized on mammalian tissue using an ice matrix. The corresponding improvement in spatial resolution facilitates the future expansion of IR‐MALDESI applications to include those that require fine structural detail. [ABSTRACT FROM AUTHOR]

Rationale: The high sensitivity of the miniature mass spectrometer plays an irreplaceable role in rapid on‐site detection. However, its analysis accuracy and stability should be improved due to the influence of sample pretreatment and use environment. The present study investigates the processing effects of ensemble empirical mode decomposition (EEMD) feature enhancement methods on the determination coefficient (R2) and relative standard deviation (RSD) of caffeine mass spectrometry (MS) signals. Methods: This paper employs the EEMD method combined with polynomial curve fitting to enhance the characteristics of seven caffeine mass spectrum signals with different concentrations and 15 groups of caffeine mass spectrum signals with the same concentration, and the wavelet analysis method was used for comparative verification. The determination coefficient and RSD of the two methods were compared. Results: We found the EEMD method's capability in adaptively decomposing caffeine mass spectrum signals is better than wavelet analysis method. The determination coefficient of the EEMD enhanced feature is better than 0.999, and the RSD is better than 2%, and both are better than wavelet analysis methods. Conclusions: The feature enhancement processing using the EEMD method has significantly improved the determination coefficient and RSD of the sample curve, improving the accuracy and stability of the data and providing a new way for miniature mass spectrometer signal processing. [ABSTRACT FROM AUTHOR]

RATIONALE: Various disease conditions, particularly tumours, can be understood easily by studying changes in the lipid profile of cells. While lipid profiles of tissues have been recorded by desorption electrospray ionization mass spectrometric (DESI-MS) imaging, there is paucity in standardized protocols for sample preparation involving cell cultures to generate reliable results. In this study, we report a method for the direct analysis of lipids from cultured cells by incorporating them onto Whatman 42 filter paper as a substrate for reliable DESI-MS analysis. METHODS: The WERI-RB1 cell line was spotted on commonly used substrates for DESI-MS analysis, such as glass slides, Teflon coated glass slides, thin layer chromatography (TLC) plates, and Whatman 42 filter paper. A comparison of mass spectrometric images with two different lipids was made to understand the behaviour of different surfaces when the same sample was spotted on them. Relative intensities of different lipid peaks in the WERI-RB1 cell line were compared and relative lipid abundances were also compared across two different human retinoblastoma cell lines; WERI-RB1 and Y79. RESULTS: The study demonstrates that good lipid signals can be obtained by DESI-MS when the cells are spotted on Whatman 42 filter paper. Tandem mass spectrometry was performed to identify the lipids as glycerophosphocholines (PC). Better lipid images from assembly of cells were obtained with distinct boundary when they were spotted on Whatman 42 filter paper than other surfaces. CONCLUSIONS: We demonstrate the use of a simple substrate for reliable DESI-MS analysis of cultured cells. This method has the potential to understand various interactions of cells with other external agents. The current method would help in the application of DESI-MS for biology in general and medical sciences in particular. [ABSTRACT FROM AUTHOR]

Mass spectrometry imaging (MSI) is increasingly used to produce chemical images of latent fingerprints. Yet, the actual benefits of MSI for real case studies have to be assessed for fingerprints previously processed by forensic techniques. Here, we have evaluated the compatibility of desorption electrospray ionization (DESI) with the fingerprint enhancement technique involving Oil Red O (ORO). Methods: To optimize the ionization step independently from surface extraction, the ORO reagent and its mixture with model compounds (triolein and linoleic acid) were first studied in solution using high-resolution electrospray ionization tandem mass spectrometry (ESI-MS/MS). Then, DESI-MSI experiments were performed in both polarity modes for ORO-processed fingermarks deposited on pieces of paper used as porous substrates. Results: ESI-MS of ORO reveals a complex mixture of azo dyes. Two main impurities detected beside the targeted species were characterized using MS/MS and then were usefully employed to produce DESI-MS images of fingermarks, decreasing the scanning rate to get sufficient ion abundance from natural fingerprints. ORO did not prevent chemical profiling, and one major added value of this pink dye was to produce MS images with contrast that cannot be obtained optically for some colored substrates. Conclusions: DESI-MS has demonstrated imaging compatibility with the application of ORO used to enhance latent fingerprints on paper and could also enable chemical profiling in natural fingermarks. In addition, MS images of ORO impurities were of higher quality than optical ones for fingerprints revealed on colored paper. [ABSTRACT FROM AUTHOR]

Rationale: We describe a novel method for preparing milk samples and profiling their triglyceride (TG) fractions. This method was used to explore how the TG profile of milk modulates as lactation progresses and how the TG profile differs between breasts. Methods: Fresh milk was spotted onto Whatman filter paper and air‐dried. Liquid Extraction Surface Analysis coupled to Fourier Transform Mass Spectrometry (LESA‐MS) was adapted for molecular profiling. Collision‐Induced Dissociation (CID) was used to profile fatty acid residues. Results: LESA‐MS produced the relative abundances of all isobaric TGs described and showed that mammary glands within one individual can produce a different profile of TGs. CID was used to uncover the configuration of isobaric triglycerides, indicating the relative amounts of the fatty acids contributing to that triglyceride's mass. This also indicated the presence of very long chain fatty acids (C26:0 and C26:1) that have not been reported before in human breast milk. Conclusions: We conclude that spotting on paper and the use of LESA‐MS and CID on milk spots is not only a means for analysing milk in unprecedented detail for this preparation time, but is also amenable to conditions in which collecting and storing fresh milk samples for detailed profiling is prohibitively difficult. [ABSTRACT FROM AUTHOR]

Rationale: An LC–MS/MS method was established to measure tigecycline in dried blood spots (DBSs). Methods: The DBS specimens obtained by applying 30 μl of blood to filter paper were extracted with hydrogen oxide and subsequently precipitated protein with perchloric acid, then the extract was directly analyzed by liquid chromatography tandem mass spectrometry. A Hypersil GOLD aQ column was utilized for separating the analytes, and detection was carried out in positive and selective reaction monitoring modes. The precursors to product ion transitions m/z 586.3 → 513.1 and m/z 586.3 → 569.2 were monitored for tigecycline, and m/z 473.2 → 456.0 and m/z 473.2 → 367.0 for 9‐amino minocycline as internal standard. Results: The validation parameters of specificity and selectivity, linearity (0.02–5 μg ml−1), sensitivity (limit of quantification 0.02 μg ml−1), intra‐ and interday precision (within 15%) and relative error (within ±15%) were acceptable. The recoveries were from 84.65% to 90.49% and from 85.41% to 95.72% for tigecycline and internal standard, respectively, and the matrix effect was not evident to influence accuracy. The impact of hematocrit on measurement of the analyte was negligible, and after preserving at ambient temperature for 24 h and at 4°C for 1 month it remained steady. Conclusions: The advantages of nonintrusive blood collection and micro‐volume sample requirements make DBS a potent surrogate to conventional venepuncture for sampling. [ABSTRACT FROM AUTHOR]

Rationale: To open up new ways for matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS)‐based patient screening, blood serum is the most preferred specimen because of its richness in patho‐physiological information and due to ease of collection. To overcome deleterious freeze/thaw cycles and to reduce high costs for shipping and storage, we sought to develop a procedure which enables MALDI‐MS protein profiling of blood serum proteins without the need for serum freezing. Methods: Blood sera from patients/donors were divided into portions which after pre‐incubation were fast frozen. Thawed aliquots were deposited on filter paper discs and air‐dried at room temperature. Intact serum proteins were eluted with acid‐labile detergent‐containing solutions and were desalted by employing a reversed‐phase bead system. Purified protein solutions were screened by MALDI‐MS using standardized instrument settings. Results: MALDI mass spectra from protein solutions which were eluted from filter paper discs and desalted showed on average 25 strong ion signals (mass range m/z 6000 to 10,000) from intact serum proteins (apolipoproteins, complement proteins, transthyretin and hemoglobin) and from proteolytic processing products. Semi‐quantitative analysis of three ion pairs: m/z 6433 and 6631, m/z 8205 and 8916, as well as m/z 9275 and 9422, indicated that the mass spectra from either pre‐incubated fast‐frozen serum or pre‐incubated dried serum spot eluted serum contained the same information on protein composition. Conclusions: A workflow that avoids the conventional cold‐chain and yet enables the investigation of intact serum proteins and/or serum proteolysis products by MALDI‐MS profiling was developed. The presented protocol tremendously broadens the clinical application of MALDI‐MS and simultaneously allows a reduction in the costs for storage and shipping of serum samples. This will pave the way for clinical screening of patients also in areas with limited access to health care systems, and/or specialized laboratories. [ABSTRACT FROM AUTHOR]

Rationale: We show evidence of cysteinylation on Cys252 of recombinant human p40 subunit of interleukin 12 (IL‐12). This was reported in 1996. However, no paper detailing this concept has been published yet. Our paper reports the quantification of Cys252 cysteinylation as well as the full disulfide bridges assignment by nonreducing peptide mapping using mass spectrometry (MS) detection. Methods: Nonreducing peptide mapping was applied for disulfide bridges assignment. This study presents an ad hoc method in which applying a neutral pH in the presence of an alkylating agent allowed to mitigate the formation of artifacts such as reshuffled disulfide bridges and permitted the detection of free cysteine. Ultra‐high‐performance liquid chromatography–MS analysis was performed on a Waters quadrupole time‐of‐flight Xevo G2‐XS mass spectrometer acquiring data in MSE mode. MS data were processed using Expressionist MS Refiner 13.5 (Genedata). Results: Scouting experiments were performed using two batches of drug substance. An in‐depth study of the LC tandem mass spectrometry profiles revealed the presence of additional species related to "free" Cys252; this cysteine residue was also detected in its S‐cysteinylated and S‐homocysteinylated forms. This result is consistent with that reported in literature so far. The relative abundance of overall "cysteinylated" species resulted in the range between 46% and 36%, which has also been confirmed using orthogonal techniques such as Ellman's assay. Conclusions: Our data clearly demonstrate that the free cysteine (Cys252) on the p40 subunit of recombinant IL‐12 is also present in its cysteinylated and homocysteinylated forms at a considerable rate. Our observations, although based on results obtained on an IL‐12‐derived fusion protein, are consistent with the current literature. [ABSTRACT FROM AUTHOR]

Rationale: The applications shared in this paper demonstrate the wide variety of samples that can be analyzed when Laser Diode Thermal Desorption (LDTD) is interfaced with a high-resolution mass spectrometer and show the speed at which high quality data can be generated from complex matrices. Methods: Samples are solvent extracted and spotted in a 96-well plate. In the case of biological fluids, hydrolysis followed by solid-phase extraction is required. The solvent in the 96-well plate is evaporated followed by mass spectrometric (MS) analysis with atmospheric pressure chemical ionization. Where applicable, the instrument is operated in data-dependent mode, with a full-scan mass spectrum followed by MS/MS spectra of the top 10 ions with a total runtime of 0.4 min. Results: Four applications (MAAQ and Tear Gas, twelve rodenticides, seven explosives, and 40 drugs of abuse) are reported in this paper. MAAQ, tear gas, and rodenticides were identified by full-scan, followed by MS/MS experiments at levels of 125 μg/L, 125 μg/L, and 500 μg/L, respectively. Explosives were all identified at 102 μg/L by full-scan experiments. The drugs of abuse were identified by multiple reaction monitoring (MRM) experiments at defined cutoff levels from 2 to 1000 μg/L. Conclusions: Interfacing LDTD with a mass spectrometer allows for rapid screening of a wide range of samples, with either minimal or complex sample preparation. Using a high-resolution mass spectrometer with the combination to perform full-scan and MS/MS experiments adds a high level of specificity. [ABSTRACT FROM AUTHOR]

Rationale: Atmospheric pressure matrix‐assisted laser desorption/ionization (AP‐MALDI) mass spectrometry has enabled the untargeted analysis and imaging of neuropeptides and proteins in biological tissues under ambient conditions. Sensitivity in AP‐MALDI can be improved by using sample‐specific preparation methods. Methods: A comprehensive and detailed optimization strategy including instrument parameters, matrix spraying and sample tissue washing pretreatment was implemented to enhance the sensitivity and coverage of neuropeptides in mouse pituitary tissues by commercial AP‐MALDI mass spectrometry imaging (MSI). Results: The sensitivity of a commercial AP‐MALDI system for endogenous neuropeptides in mouse pituitary was enhanced by up to 15.2‐fold by shortening the transmission gap from the sample plate to the inlet, attaching copper adhesive tape to an indium tin oxide‐coated glass slide, optimizing the matrix spray solvent and using sample tissue washing pretreatment. Following careful optimization, the distributions of nine endogenous neuropeptides were successfully visualized in the pituitary. Furthermore, the quantitative capability of AP‐MALDI for neuropeptides was evaluated and the concentrations of neuropeptides oxytocin and vasopressin in the pituitary posterior lobe were increased approximately twofold under hypertonic saline stress. Conclusion: Mouse pituitary neuropeptides have emerged as important signaling molecules due to their role in stress response. This work indicates the potential of modified AP‐MALDI as a promising AP MSI method for in situ visualization and quantification of neuropeptides in complex biological tissues. [ABSTRACT FROM AUTHOR]

Rationale: Sulfur isotopes have been widely used to solve some key scientific questions, especially in the last two decades with advanced instruments and analytical schemes. Different sulfur speciation and multiple isotopes analyzed in laboratories worldwide and in situ microanalysis have also been reported in many articles. However, methods of sampling to measurements are multifarious, and occasionally some inaccuracies are present in published papers. Vague methods may mislead newcomers to the field, puzzle readers, or lead to incorrect data‐based correlations. Methods: We have reviewed multiple methods on sulfur isotopic analyses from the perspectives of sampling, laboratory work, and instrumental analysis in order to help reduce operational inhomogeneity and ensure the fidelity of sulfur isotopic data. We do not deem our proposed solutions as the ultimate standard methods but as a lead‐in to the overall introduction and summary of the current methods used. Results: It has been shown that external contamination and transformation of different sulfur species should be avoided during the sampling, pretreatment, storage, and chemical treatment processes. Conversion rates and sulfur isotopic fractionations during sulfur extraction, purification, and conversion processes must be verified by researchers using standard or known samples. The unification of absence of isotopic fractionation is needed during all steps, and long‐term monitoring of standard samples is recommended. Conclusion: This review compiles more details on different methods in sampling, laboratory operation, and measurement of sulfur isotopes, which is beneficial for researchers' better practice in laboratories. Microanalyses and molecular studies are the frontier techniques that compare the bulk sample with the elemental analysis/continuous flow–gas source stable isotope ratio mass spectrometry method, but the latter is widely used. The development of sulfur isotopic measurements will lead to the innovation in scientific issues with sulfur proxies. [ABSTRACT FROM AUTHOR]

Rationale: This paper describes an in vitro study designed to identify metabolic biomarkers resulting from the conjugation of nitrogen mustards (NMs) with glutathione (GSH). The method developed is essential in providing evidence in the event of NM exposure in biomedical samples. Methods: The mass spectral characterization of the proposed NMs-GSH conjugates was performed with liquid chromatography high-resolution tandem mass spectrometry (LC-HRMS/MS). The final reaction mixtures were analysed in positive electrospray ionisation (ESI) at different incubation times. Results: This study identified three types of conjugates in addition to ethanolamines, the hydrolysis products of NMs. Monoglutathionyl, diglutathionyl and phosphorylated conjugates were produced for each of the NMs, bis(2-chloroethyl) ethylamine (HN1), bis(2-chloroethyl)methylamine (HN2) and tris(2-chloroethyl)amine (HN3). The monoglutathionyl conjugates consisted of HN1-GSH, HN2-GSH and HN3-GSH. The spontaneous and primary conjugates of diglutathionyl were HN1-GSH2, HN2-GSH2 and HN3-GSH2. These included phosphorylated conjugates, namely HN1-GSH-PO4, HN2-GSH-PO4 and HN3-GSH-PO4, as might have formed due to hydrolysis in phosphate buffer. Conclusions: The mass spectral data of all conjugates formed in the presence of all NMs and GSH are reported in this study. These GSH metabolites can be used to confirm NMs toxicity in biological samples such as urine. [ABSTRACT FROM AUTHOR]

Rationale: The observed isotope distribution is an important attribute for the identification of peptides and proteins in mass spectrometry-based proteomics. Sulphur atoms have a very distinctive elemental isotope definition, and therefore, the presence of sulphur atoms has a substantial effect on the isotope distribution of biomolecules. Hence, knowledge of the number of sulphur atoms can improve the identification of peptides and proteins. Methods: In this paper, we conducted a theoretical investigation on the isotope properties of sulphur-containing peptides. We proposed a gradient boosting approach to predict the number of sulphur atoms based on the aggregated isotope distribution. We compared prediction accuracy and assessed the predictive power of the features using the mass and isotope abundance information from the first three, five and eight aggregated isotope peaks. Results: Mass features alone are not sufficient to accurately predict the number of sulphur atoms. However, we reach near-perfect prediction when we include isotope abundance features. The abundance ratios of the eighth and the seventh, the fifth and the fourth, and the third and the second aggregated isotope peaks are the most important abundance features. The mass difference between the eighth, the fifth or the third aggregated isotope peaks and the monoisotopic peak are the most predictive mass features. Conclusions: Based on the validation analysis it can be concluded that the prediction of the number of sulphur atoms based on the isotope profile fails, because the isotope ratios are not measured accurately. These results indicate that it is valuable for future instrument developments to focus more on improving spectral accuracy to measure peak intensities of higher-order isotope peaks more accurately. [ABSTRACT FROM AUTHOR]

Rationale: SLAP is one of the two calibration materials for the isotopic water scale. By consensus the established δ18O value is −55.5‰, although several expert laboratories measure significantly more negative δ18OSLAP values. The real δ18OSLAP value as such does not influence the isotopic water scale; however, knowledge of the size of isotopic scale contraction in stable isotope measurements is vital for second‐order isotopes. This study describes the quantification of δ18OSLAP with respect to δ18OVSMOW. Methods: SLAP‐like water was quantitatively mixed with highly 18O‐enriched water to mimic VSMOW. The 18O concentration was determined using an electron ionization quadrupole mass spectrometer. The isotopic composition of the SLAP‐like and VSMOW‐like waters was measured using an optical spectrometer, alongside original VSMOW and SLAP. Results: This study resulted in a much more negative δ18O value for SLAP than expected. The averaged outcome of seven independent experiments is δ18OSLAP = −56.33 ± 0.03‰. There is a large discrepancy between the actual isotopic measurements of even the most carefully operating isotope laboratories and the true δ18O value. Conclusions: Although this finding as such does not influence the use of the VSMOW–SLAP scale, it raises the intriguing question of what we actually measure with our instruments and why even a fully corrected measurement can be so far off. Our result has consequences for issues like the transfer of δ18O from and to the VPDB scale, various fractionation factors, and Δ17O. The absolute 18O abundance for SLAP was calculated as (1887.98 ± 0.43) × 10−6 based on the absolute 18O abundance of VSMOW and the presented δ18OSLAP in this paper. [ABSTRACT FROM AUTHOR]

Rationale Methods Results Conclusions Higher resolution in fieldable mass spectrometers (MS) is desirable in space flight applications to enable resolving isobaric interferences at m/z < 60 u. Resolution in portable cycloidal MS coupled with array detectors could be improved by reducing the slit width and/or by reducing the width of the detector pixels. However, these solutions are expensive and can result in reduced sensitivity. In this paper, we demonstrate high‐resolution spectral reconstruction in a cycloidal coded aperture miniature mass spectrometer (C‐CAMMS) without changing the slit or detector pixel sizes using a class of signal processing techniques called super‐resolution (SR).We developed an SR reconstruction algorithm using a sampling SR approach whereby a set of spatially shifted low‐resolution measurements are reconstructed into a higher‐resolution spectrum. This algorithm was applied to experimental data collected using the C‐CAMMS prototype. It was then applied to synthetic data with additive noise, system response variation, and spatial shift nonuniformity to investigate the source of reconstruction artifacts in the experimental data.Experimental results using two ½ pixel shifted spectra resulted in a resolution of ¾ pixel full width at half maximum (FWHM) at m/z = 28 u. This resolution is equivalent to 0.013 u, six times better than the resolution previously published at m/z = 28 for N2+ using C‐CAMMS. However, the reconstructed spectra exhibited some artifacts. The results of the synthetic data study indicate that the artifacts are most likely caused by the system response variation.This paper demonstrates super‐resolution spectral reconstruction in C‐CAMMS without changing the slit or detector pixel sizes using a sampling SR approach. With improvements, this technique could be used to resolve isobaric interferences in a portable cycloidal MS for space flight applications. [ABSTRACT FROM AUTHOR]

Rationale: The development of appropriate analytical screening techniques for pharmaceuticals and personal care products (PPCPs) is the basis for studying the distribution and environmental impact of emerging contaminants (ECs). Mass spectrometry‐based screening methods vary with the complexity of the target compounds. It is challenging to balance both positive and negative ion quantification with a low detection limit. To establish a set of experimental methods including extraction, chromatography‐separation and mass spectrometry screening is one of the most important topics in PPCP research. This paper describes a universal and efficient qualification and quantification protocol for the simultaneous detection of 34 PPCPs in different environmental samples in a single analytical data acquisition run. Methods: Thirty‐four representative PPCPs, which are widely distributed in the environment with high ecological toxicity and complex chemical structures, were selected as representative target ECs. The extraction of the target PPCPs was achieved using only one solid‐phase extraction cartridge without the need to adjust the pH of samples. The enriched samples were detected by LC–MS/MS in both positive and negative ion modes simultaneously. The protocol was evaluated based on the accuracy, precision, detection limits and matrix effects. Results: This method achieved simultaneous detection of PPCPs in both positive and negative ion modes, with a single analytical cycle of 12 min. The observed SPE recoveries were between 40% and 115%. The instrumental detection limits (IDL) varied from 0.01 to 1 pg, and the method detection limits (MDL) were between 0.002 and 3.323 ng/l in different matrices. Most of the PPCPs were subjected to matrix suppression below 30%. The method was successfully applied for quantitative analysis of the PPCPs in different environmental samples, including river samples, wastewater treatment plant (WWTP) samples and soil samples. Conclusions: This protocol developed a rapid and efficient detection method to simultaneous qualitative and quantitative 34 representative PPCPs in the environment. The IDL ranged from 0.01 to 1 pg and the MDL ranged from 0.002 to 3.323 ng/l in different matrices. The detection limit was one order of magnitude lower compared to previous studies. The protocol also provided a wide application range for different environmental matrices, which permitted the migration and transformation of PPCPs to be explored. [ABSTRACT FROM AUTHOR]

Rationale: Quantifications of quadruple sulfur isotopic compositions (δ34S, Δ33S, and Δ36S) of sulfur‐bearing compounds in nature are valuable for providing new insights into the Earth's evolution such as the crust–mantle cycle, oxygenation of atmosphere and oceans, and the origin and evolution of early life. SF6‐based isotope ratio mass spectrometry is the most widely used method of quantification, but Δ36S measurements at high precision and accuracy have always been technically difficult due to the low abundance of 36S (~0.01%). In this paper, we identify a major source of isobaric interferences (i.e., contamination in helium carrier gas in the gas chromatography purification step) and propose a simple strategy to solve this problem. Methods: An SF6 fluorination and purification system was built. Laboratory SF6 reference gas and international Ag2S standard (IAEA‐S1) were used as reference materials to test our method. Contamination from helium carrier gas (99.999%) was purified by a simple two‐step cryogenic method to allow for accurate and precise measurements of Δ36S using the SF6‐based isotope ratio mass spectrometry method. Results: Without proper purification of helium carrier gas, large errors in Δ36S measurements were found. Measured Δ36S values of SF6 with trace contamination from helium were >10‰ higher than expected values. Using a newly developed purification strategy, the difference in Δ36S values of SF6 before and after passing through the gas chromatography is less than instrumental errors (<0.2‰). Our improved method yielded an overall Δ36S precision for IAEA‐S1 of 0.12‰ (n = 6). This precision is comparable to that found by other laboratories around the world. Conclusion: Our simple two‐step cryogenic method significantly improved the accuracy and precision of Δ36S measurements and is therefore recommended for future determination of quadruple sulfur isotopic compositions in natural samples. [ABSTRACT FROM AUTHOR]

Rationale: The development of miniaturized and field portable mass spectrometers could not succeed without a simple, compact, and robust ionization source. Here we present a voltage‐free ionization method, Vibrating Sharp‐edge Spray Ionization (VSSI), which can generate a spray of liquid samples using only one standard microscope glass slide to which a piezoelectric transducer is attached. Compared with existing ambient ionization methods, VSSI eliminates the need for a high electric field (~5000 V·cm−1) for spray generation, while sharing a similar level of simplicity and flexibility with the simplest direct ionization techniques currently available such as paper spray ionization (PSI) and other solid substrate‐based electrospray ionization methods. Methods: The VSSI device was fabricated by attaching a piezoelectric transducer onto a standard glass microscope slide using epoxy glue. Liquid sample was aerosolized by either placing a droplet onto the vibrating edge of the glass slide or touching a wet surface with the glass edge. Mass spectrometric detection was achieved by placing the VSSI device 0.5–1 cm from the inlet of the mass spectrometer (Q‐Exactive, ThermoScientific). Results: VSSI is demonstrated to ionize a diverse array of chemical species, including small organic molecules, carbohydrates, peptides, proteins, and nucleic acids. Preliminary sensitivity experiments show that high‐quality mass spectra of acetaminophen can be obtained by consuming 100 femtomoles of the target. The dual spray of VSSI was also demonstrated by performing in‐droplet denaturation of ubiquitin. Finally, due to the voltage‐free nature and the direct‐contact working mode of VSSI, it has been successfully applied for the detection of chemicals directly from human fingertips. Conclusions: Overall, we report a compact ionization method based on vibrating sharp‐edges. The simplicity and voltage‐free nature of VSSI make it an attractive option for field portable applications or analyzing biological samples that are sensitive to high voltage or difficult to access by conventional ionization methods. [ABSTRACT FROM AUTHOR]

Rationale: Pyrrolidone‐based drugs find widespread use in treating conditions such as epilepsy and Alzheimer's disease, and in various other medical applications. Brivaracetam, the latest generation of pyrrolidone drugs, has exhibited significant promise owing to chemical structure modifications. Its affinity to the SV2A receptor is double that of the previous‐generation drug, levetiracetam. Consequently, brivaracetam holds substantial potential for diverse applications. As a novel drug not yet included in the pharmacopeias of developed nations, comprehensive analysis and research are necessary to guarantee its safe utilization in clinical settings. Methods: A liquid chromatography quadrupole time‐of‐flight tandem mass spectrometry (LC/QTOFMS) method has been developed to effectively separate, identify and characterize both the degradation products and process‐related substances of brivaracetam. Stress testing of the sample was carried out following the guidelines outlined in ICH Q1A(R2). The structures of these impurities were identified through positive electrospray ionization QTOF high‐resolution MS and NMR spectroscopy. Additionally, the formation mechanism of each degradation product is thoroughly discussed. Results: Under the analytical conditions outlined in this paper, brivaracetam and its degradation products were effectively separated. Thirteen degradation products were detected and characterized, shedding light on their origins and degradation pathways. Among these, three degradation products align with previously reported impurities, and two unreported degradation products were synthesized and confirmed through NMR spectroscopy. The stress testing results revealed the instability of brivaracetam under acidic, alkaline, oxidative and thermal stress conditions, while it exhibited relative stability under photolytic stress conditions. Conclusion: The study developed an analytical method for brivaracetam that enabled the effective detection and separation of brivaracetam and its 13 degradation products. This method addresses a gap in both current domestic and foreign drug standards. The structures of all the major degradation products were characterized by high‐resolution LC/QTOFMS, which is essential for quality control during the drug production process, stability evaluation and the establishment of proper storage conditions. [ABSTRACT FROM AUTHOR]