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ICP-OES is a powerful, versatile, and advanced analytical technique with excellent detection properties. Due to its extraordinary features, it has been widely employed for the analysis of a wide variety of chemical elements in the past few years with great success. It offers the least detection time, lower detection limits, broader linear dynamic range, and greater matrix tolerability as well as negligible chemical interferences. Beyond this, it can handle multiple varieties of samples including aqueous, inorganic, organic liquids, and solids as well. It comprises complex instrumental makeup which enables it to detect up to 2 to 70 elements simultaneously with great accuracy. Recent reports evidenced that this hyphenated technique has been employed in several analytical determinations including food analysis, agricultural investigations, geological studies, drug/metabolite analysis, and environmental and forensic sciences. In the present compilation, a detailed description of the fundamental principles of ICP-OES has been provided along with its various sophisticated functional components. Also, the reported applications of this technique in different fields have been discussed highlighting the basic experimental setups and outcomes by presenting the data as tables. This summarization may be helpful to analysts to get insights into the working as well as performance characteristics of this technique.

In-source fragmentation-based high-resolution mass spectrometry (ISF-HRMS) is a potential analytical technique, which is usually used to profile some specific compounds that can generate diagnostic neutral loss (NL) or fragment ion (FI) in ion source inherently. However, the ISF-HRMS method does not work for those compounds that cannot inherently produce diagnostic NL or FI in ion source. In this study, a derivatization-based in-source fragmentation-information-dependent acquisition (DISF-IDA) strategy was proposed for profiling the metabolites with easily labeled functional groups (submetabolomes) by liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry (LC-ESI-Q-TOF MS). As a proof-of-concept study, 36 carboxylated compounds labeled with N,N-dimethylethylenediamine (DMED) were selected as model compounds to examine performance of DISF-IDA strategy in screening the carboxylated metabolites and acquiring their MSn spectra. In ESI source, the DEMD-derived carboxylated compounds were fragmented to produce characteristic neutral losses of 45.0578, 63.0684, and/or 88.1000 Da that were further used as diagnostic features for screening the carboxylated metabolites by DISF-IDA-based LC-Q-TOF MS. Furthermore, high-resolution MSn spectra of the model compounds were also obtained within a single run of DISF-IDA-based LC-Q-TOF MS analysis, which contributed to the improvement of the annotation confidence. To further verify its applicability, DISF-IDA strategy was used for profiling carboxylated submetabolome in mice feces. Using this strategy, a total of 351 carboxylated metabolites were detected from mice feces, of which 178 metabolites (51% of the total) were positively or putatively identified. Moreover, DISF-IDA strategy was also demonstrated to be applicable for profiling other submetabolomes with easily labeled functional groups such as amino, carbonyl, and cis-diol groups. Overall, our proposed DISF-IDA strategy is a promising technique for high-coverage profiling of submetabolomes with easily labeled functional groups in biological samples.

The analytical technique has been developed for the extraction and determination of uranium(VI). This process is based on the ion-pair complex formation of uranium(VI) with 2-octylaminopyridine in xylene. Uranium(VI) is quantitatively extracted by optimizing the parameters of solvent extraction in presence of sodium acetate, such as pH, concentration of weak organic acids, strippant, shaking period, solvent study, and concentration of extractant. A mechanism of extraction was proposed based on the slope ratio analysis method. The interference of various cations and anions was also investigated. The versatility of the developed method was investigated by employing it to binary and ternary mixtures. The robustness of the method was demonstrated by determining uranium(VI) in the bone sample.

Near-infrared spectroscopy and chemometrics were investigated as a rapid analytical method to evaluate quality parameters of acai oil during thermal oxidation under accelerated conditions. A two-factors full factorial design with 2 levels for the treatment (without antioxidant and with 400 ppm of myricetin) and 8 levels for the oxidation time (giving insight of the initial stage of oil oxidation) was used. Three quality parameters (peroxide, conjugated diene, and p-anisidine values) were monitored by reference analysis. Multi-factorial analysis of variance and estimation of the order of the kinetic models pointed out that both factors and their interaction had a significant effect on the quality parameters (p value 0.83) and ratio of prediction to deviation (> 2.9) that indicated good performance for the prediction of new independent samples. High sensitivity (> 83%) and accuracy (> 95%) of the linear discriminant analysis, obtained when the first derivative was used as pre-treatment, were indicators of a suitable technique for classifying new independent samples. Principal component analysis showed the formation of two clusters corresponding to acai oil samples safe and unfit for commercialization. In conclusion, near-infrared spectroscopy revealed to be a powerful alternative analytical technique for prediction and classification of acai oil samples at industrial scale.

Single-molecule (SM) quantification has become a powerful analytical technique in the fields of physics, chemistry, and biology. SM imaging, especially with super-resolution (SR) techniques, has dramatically facilitated the study of individual molecules that may function as disease-related biomarkers. Although multiple properties can be used for quantitative imaging analysis, counting may be the simplest and most direct way. Consequently, how to utilize the greater spatial resolution to overcome undercounting or overcounting errors in certain conditions shows promising potential to unravel intracellular mechanisms of isolated biomolecules. From this perspective, we present an absolute quantification approach, termed crucial connected-component entropy (CCCE), with subresolution accuracy for the SR SM detection platform without the need for prior knowledge of calibration, and a cross-validation analytical pipeline based on SM profiling for nanoscale performance assessments. Considering its high efficiency, accuracy, and robustness for routine SM quantification compared with commonly used strategies, we believe that this protocol will indubitably find wide applications in biochemistry research, drug discovery, and clinical diagnostics, especially molecular diagnostics.

Chromium contamination of soil and water is a serious environmental and public health concern as the hexavalent form of chromium [Cr(VI)] is readily soluble in water and is a confirmed carcinogen. There is an imminent need for a robust, low-cost, and simple analytical technique to facilitate in situ monitoring of Cr(VI) in water. Current quantitative methods of Cr(VI) detection are largely laboratory-based, time-consuming, expensive, and require training for implementation. In this contribution, a portable, easy-to-use, and compact measuring tool is presented that provides Cr(VI) concentration within 10 min of water sampling over a linear range of 0–3 mg L−1. This tool utilizes a relatively inexpensive camera-enabled smartphone with a custom-made test chamber attachment to seamlessly perform Cr(VI) measurements on water samples in the field. For analysis, an android-based software application was developed that directs the user to perform a simple series of steps following the diphenylcarbazide-based colorimetric method prescribed by the American Public Health Association. The tool was validated against a standard UV-visible spectrophotometer for a variety of synthetic and naturally contaminated water samples, with correlation factors greater than 0.993 (p

Success of a drug discovery program is highly dependent on rapid scientific advancement and periodic inclusion of sensitive and specific analytical techniques. Biological membrane transporters can significantly alter the bioavailability of a molecule in its actual site of action. Expression of transporter proteins responsible for drug transport is extremely low in the biological system. Therefore, proper scientific planning in selection of their quantitative analytical technique is essential. This article discusses critical advancement in the analytical strategies for quantification of clinically relevant biological transporters for the drugs. Article cross-talked key planning and execution strategies concerning analytical quantification of the transporters during drug discovery programs.

An analytical technique was developed to determine the age of uranium particles. After the chemical separation of uranium and thorium, the 230Th/234U ratio was measured using single-collector inductively coupled plasma mass spectrometry and a 233U-based reference material comprising a certain amount of 229Th as a progeny nuclide of 233U. The results allowed us to determine the purification age of two certified materials, i.e., U-850 and U-100, which was in good agreement with the reference purification age (61 y). Moreover, the age of a single U-850 particle was determined with a difference of − 28 to 2 years from the reference date.

Surface-enhanced Raman spectroscopy (SERS) is an emerging analytical technique for chemical analysis, which is favourable due to its combination of short measurement time, high sensitivity and molecular specificity. However, the application of SERS is still limited, largely because in real samples the analyte is often present in a complex matrix that contains micro/macro particles that block the probe laser, as well as molecular contaminants that compete for the enhancing surface. Here, we show a simple and scalable spray-deposition technique to fabricate SERS-active paper substrates which combine sample filtration and enhancement in a single material. Unlike previous spray-deposition methods, in which simple colloidal nanoparticles were sprayed onto solid surfaces, here the colloidal nanoparticles are mixed with hydroxyethyl cellulose (HEC) polymer before application. This leads to significantly improved uniformity in the distribution of enhancing particles as the film dries on the substrate surface. Importantly, the polymer matrix also protects the enhancing particles from air-oxidation during storage but releases them to provide SERS enhancement when the film is rehydrated. These SERS-paper substrates are highly active and a model analyte, crystal violet, was detected down to 4 ng in 10 μL of sample with less than 20% point-by-point signal deviation. The filter paper and HEC effectively filter out both interfering micro/macro particles and molecular (protein) contaminants, allowing the SERS-paper substrates to be used for SERS detection of thiram in mud and melamine in the presence of protein down to nanogram levels without sample pre-treatment or purification.

Analytical techniques for analyte quantification are often complex, time-consuming, and costly. Further, samples must be carefully prepared to make them suitable for each analytical technique, thus increasing complexity and cost and often requiring toxic solvents. In this paper, we propose a simple and quick method for the pre-concentration of analytes using a nonporous adsorbent: nanosilica, which is prepared from rice husks, an ecofriendly waste material. Subsequently, analysis using high-performance liquid chromatography with a photodiode array detector was used for accurate analyte quantification. To test our method, Sudan I and II dyes were selected because these are potential carcinogens that are often used to adulterate foods because of their bright colors. Although nanosilica has been used as an adsorbent before, the adsorption of hydrophobic organic dyes has not been investigated to date. Thus, the optimal conditions for dye adsorption on nanosilica were systematically studied and found to be 1 mM KCl, pH 3.0, and an adsorption time of 120 min, and the maximum adsorption capacities of the nanosilica for Sudan I and II were 0.619 and 0.699 mg·g−1, respectively. The adsorption of the dyes on the nanosilica is discussed in detail with respect to the surface area, functional groups, zeta potential, and adsorption isotherms. Under optimal conditions, the extraction efficiencies of Sudan I and Sudan II reached 98.3% and 92.8%, respectively, and the proposed method was applied for the analysis of several foods and achieved high recoveries (80–100%).

Electrochemical impedance spectroscopy (EIS), an extremely sensitive analytical technique, is a widely used signal transduction method for the electrochemical detection of target analytes in a broad range of applications. The use of nucleic acids (aptamers) for sequence-specific or molecular detection in electrochemical biosensor development has been extensive, and the field continues to grow. Although nucleic acid-based sensors using EIS offer exceptional sensitivity, signal fidelity is often linked to the physical and chemical properties of the electrode-solution interface. Little emphasis has been placed on the stability of nucleic acid self-assembled monolayers (SAMs) over repeated voltammetric and impedimetric analyses. We have studied the stability and performance of electrochemical biosensors with mixed SAMs of varying length thiolated nucleic acids and short mercapto alcohols on gold surfaces under repeated electrochemical interrogation. This systematic study demonstrates that signal fidelity is linked to the stability of the SAM layer and nucleic acid structure and the packing density of the nucleic acid on the surface. A decrease in packing density and structural changes of nucleic acids significantly influence the signal change observed with EIS after routine voltammetric analysis. The goal of this article is to improve our understanding of the effect of multiple factors on EIS signal response and to optimize the experimental conditions for development of sensitive and reproducible sensors. Our data demonstrate a need for rigorous control experiments to ensure that the measured change in impedance is unequivocally a result of a specific interaction between the target analyte and nucleic recognition element.

Highly precise and accurate measurements of Fe isotope ratios for fourteen reference materials from the USGS, MPI-DING and CGSG were successfully carried out using a developed analytical technique by fs LA-MC-ICP-MS. A synthetic standard, i.e., Cr-979S, was produced as a calibration standard for instrumental mass bias and isobaric interference corrections. The results for samples with low Cr concentration (54Cr/54Fe 0.0001), e.g., BHVO-2G, δ56Fe values deviated from reference values when using the standard-sample bracketing method alone. Combining the standard-sample bracketing method with Cr-979S standard corrections and standard sample cone + H skimmer cone, the measured Fe isotopic compositions of GOR128-G and GOR132-G with extremely high Cr concentrations (54Cr/54Fe > 0.01) were identical to reference values within errors (δ56Fe = −0.01 ± 0.13‰, 2SD, n = 18; δ56Fe = 0.00 ± 0.13‰, 2SD, n = 13; respectively). A series of reference materials with varying Cr concentrations, including the USGS reference glasses (BCR-2G, BHVO-2G, BIR-1G, TB-1G, NKT-1G, GSD-1G and GSE-1G), MPI-DING reference glasses (KL2-G, ML3B-G, GOR128-G and GOR132-G) and CGSG reference materials (CGSG-1 and CGSG-4), were used to test our developed method of in situ Fe isotopic measurements using the combined standard-sample bracketing method and Cr-979S standard corrections by fs LA-MC-ICP-MS. All the reference materials yield relatively homogeneous Fe isotopic compositions with δ56Fe values ranging from −0.03‰ to 0.13‰ and δ56Fe reproducibility is below 0.15‰ (2SD), suggesting that the proposed isobaric interference correction and mass bias correction method is a useful tool for providing high-quality in situ Fe isotopic data of geological samples with both low and high Cr concentrations.

There has been a recent surge in the amount of substandard and falsified clopidogrel. Pharmacopeial based assays using high performance liquid chromatography and mass spectroscopy are widely used for the measurement of clopidogrel but are not accessible in low to middle income countries. Therefore, our study explored four different techniques (mid-infrared spectroscopy, thin layer chromatography, ultraviolet visible spectroscopy, and differential pulse voltammetry), which could be used in low to middle income countries. Differential pulse voltammetry showed the best performance for accurate and precise determination of clopidogrel in the presence of excipients. Clopidogrel tablets were fully crushed and sonicated in buffer for 30 seconds prior to differential pulse voltammetry measurements using a 3 mm glassy carbon electrode. Measurements were made without removing the excipients and the limit of detection was 0.08 mg ml−1 and the sensitivity was 15.7 μA mg ml−1. When conducting a blinded study, differential pulse voltammetry was able to identify varying types of substandard and falsified samples. Our findings highlight that voltammetry could be a vital analytical technique for the determination of substandard and falsified medicines in low- and middle-income countries.

Zirconium isotope is a very promising tracer to investigate geological processes such as magmatic crystallization and differentiation, and to tackle the secular evolution of the continental crust. With zircon being its major hosting mineral, developing analytical technique with high accuracy, high precision and high efficiency is critical to facilitate its geological applications. This study presents an analytical method to measure zircon Zr isotope compositions by secondary ion mass spectrometry (SIMS). With careful sample preparation to limit the topography effect and instrumental tuning for maintaining its stability, we demonstrate that large geometry SIMS can provide zircon Zr isotope measurements with high accuracy, high precision and high efficiency. Based on extensive testing on our CAMECA IMS 1280HR, the recommended instrumental tuning parameters are: a primary beam intensity of ∼30 nA, a beam diameter of ∼20 × 15 μm2, a mass resolution power of 2400 and a raster size of 15 × 15 μm2, with 94Zr and 90Zr being collected by static Faraday cups via a signal accumulation time of 20 cycles × 4 s. By analyzing zircon reference materials commonly used for U–Pb and O analysis (i.e., 91500, Penglai, Plesovice, and Mudtank), we have achieved a δ94Zr repeatability of 0.04–0.07‰ (2SD, n = 33–75), and the Zr isotope compositions of zircon reference materials measured by SIMS agree remarkably well with those defined by double-spike solution methods. Our method consumes ∼1.2 ng materials in a single spot analysis (∼0.9 μm pit depth), together with its high spatial resolution (∼13 × 14 × 0.3 μm3 for data collection) and high efficiency (∼4 minutes per analysis), it is expected that our SIMS Zr isotope analytical method will be very useful for studying precious materials (e.g., zircon in lunar soil) and to facilitate big data research (e.g., detrital zircon study).

Low activities of radionuclides in environmental and occupational samples demand for the lower detection limits of the measuring system, which can be achieved by minimizing the source-to-detector distance. Analytical technique to calculate full-energy peak efficiency and total efficiency, self-absorption of sources and a coincidence factor of the NaI cubic scintillation detector with rectangular cavity for rectangular source have been derived. The photon path length of the volumetric sources calculated and determined source self-absorption. The photon attention by rectangular sources and detector cap materials is also calculated. In the experiments gamma aqueous source containing Eu-152 radionuclide covering range from 121 to 1408 keV was used. By comparison analytical method for calculating the full energy peak efficiency and the corrected experimental efficiency values are in good a agreement.

Laser-induced breakdown spectroscopy (LIBS), as a promising analytical technique for coal analysis, is greatly affected by the matrix effect. Existing studies have a fundamental understanding of the matrix effect in coal pellets, but the matrix effect in coal particle flow has never been studied previously. This paper aims to characterize the matrix effect in the coal particle flow and compares it with that in the coal pellets. Using seven coal samples with similar carbon content but different matrices, we investigate the spectral analytical response of C I 247.86 nm to the carbon content. Additionally, the ablation crater profiling method and the fast-imaging approach have been applied to characterize the ablation mass and the laser thermal effect, followed by the in-depth analysis of the matrix effect in coal particle flow. The experimental results show that particle flow analysis can ensure stable ablation mass and alleviate the laser thermal effect. Based on these improvements, LIBS analysis of particle flow reveals a milder matrix effect compared with pellets, reducing the inconsistency of spectral analytical response from 21.64% to 12.87%.

A rapid and nondestructive analytical technique is critical for the analysis of cyclodextrin inclusion complexes in solid dosage forms. This study proposed a newly developed low-frequency Raman spectroscopy as a candidate technique for the analysis of cyclodextrin inclusion complexes. In this study, we selected a typical series of five crystalline cyclodextrin inclusion complexes and reported the usefulness of Raman spectroscopy for analyzing these inclusion complexes. Some inclusion complexes clearly differed from the raw materials in conventional Raman spectra. In another case, though specific differences were not observed between inclusion complexes and raw materials in conventional Raman spectra, clear differences were observed in low-frequency Raman spectra. Moreover, no characteristic differences between inclusion complexes consisting of different guest molecules were observed in conventional Raman spectra. The characteristic differences were observed only in low-frequency Raman spectra. Therefore, low-frequency Raman spectroscopy is a useful technique for solid-state analysis of crystalline inclusion complexes.

Hybrid material surfaces on microparticles are emerging as vehicles for many biomedical multiplexing applications. Functionalization of these hybrid surface microparticles to biomolecules presents unique challenges related to optimization of surface chemistries including uniformity, repeatability, and sample sparring. Hybrid interfaces between microlevel surfaces and individual biomolecules will provide different microenvironments impacting the surface functionalization optimization and efficiency. Here, we propose and validate the first demonstration of streptavidin adsorption-based antibody functionalization on unmodified, hybrid surface microparticles for in vitro analysis. We test this analytical technique and fabricate hybrid surface microparticles with a polystyrene core and aluminum oxide semi-coating. Additionally, we optimize the streptavidin-biotin functionalization chemistry in both assay implementation and sample sparring via analytical mass balances for these microparticles and subsequently conjugate anti-human CD11b antibodies. Result confirmation and characterization occurs from ultraviolet protein absorbance and ImageJ processing of fluorescence microscopy images. Additionally, we design and implement the multi-sectional imaging (MSI) approach to support functionalization uniformity on the hybrid surface microparticles. Finally, as a proof-of-concept performance, we validate anti-CD11b antibodies functionalization by visualizing hybrid surface microparticles conjugate to human neutrophils isolated from blood samples collected from potentially septic patients. Our study introduces and defines a category of functionalization for hybrid surface microparticles with the intent of minuscule sample volumes, low cost, and low environmental impact to be used for many cellular or proteomic in vitro multiplexing applications in the future. Graphical abstract.

Enantioseparation of chiral products has become increasingly important in a large diversity of academic and industrial applications. The separation of chiral compounds is inherently challenging and thus requires a suitable analytical technique that can achieve high resolution and sensitivity. In this context, CE has shown remarkable results so far. Chiral CE offers an orthogonal enantioselectivity and is typically considered less costly than chromatographic techniques, since only minute amounts of chiral selectors are needed. Several CE approaches have been developed for chiral analysis, including chiral EKC and chiral CEC. Enantioseparations by EKC benefit from the wide variety of possible pseudostationary phases that can be employed. Chiral CEC, on the other hand, combines chromatographic separation principles with the bulk fluid movement of CE, benefitting from reduced band broadening as compared to pressure‐driven systems. Although UV detection is conventionally used for these approaches, MS can also be considered. CE‐MS represents a promising alternative due to the increased sensitivity and selectivity, enabling the chiral analysis of complex samples. The potential contamination of the MS ion source in EKC‐MS can be overcome using partial‐filling and counter‐migration techniques. However, chiral analysis using monolithic and open‐tubular CEC‐MS awaits additional method validation and a dedicated commercial interface. Further efforts in chiral CE are expected toward the improvement of existing techniques, the development of novel pseudostationary phases, and establishing the use of chiral ionic liquids, molecular imprinted polymers, and metal‐organic frameworks. These developments will certainly foster the adoption of CE(‐MS) as a well‐established technique in routine chiral analysis.

Digital PCR (dPCR) is a highly sensitive analytical technique used to quantify DNA targets. Detection sensitivity can be further enhanced by capturing target sequences onto beads for preconcentration and sample cleanup prior to analysis in microfluidic microwell arrays. However, robust digital analysis requires individual beads to be interrogated within individual wells. Fabricating microwells with dimensions ≤ 3 μm is challenging, and the high surface area-to-volume ratio of the wells leaves PCR susceptible to inhibition stemming from materials used during device processing. This report describes the development of a microfabrication procedure to create ultralow-volume wells (100 fL) for bead-based dPCR and characterize the effects of microprocessing materials on assay performance. Standard microfabrication protocols used for creating microelectronics resulted in devices with nanoscopic debris originating from photoresists used during processing. A model dPCR assay was developed to characterize the effects of this debris, which revealed variable PCR inhibition. Debris within microwells attenuated digital and analog assay signals to a greater extent than debris on the device surface. Spatial heterogeneity of debris across devices was quantified to characterize regional PCR inhibition and intra- and inter-device variability. Ultimately, a fabrication procedure was developed to create pristine microfluidic arrays using dual processes to remove positive resist and forgoing use of negative resist entirely, which enabled robust amplification with digital signals matching theoretical predictions. Results from this work catalog the unique performance artifacts from device microfabrication and provide a guide for future studies seeking to conduct robust, high-sensitivity bead-based dPCR assays.

Nowadays, the presence of antibiotic residues in foods with animal origin has become an important challenge for public health authorities in many countries. Antibiotic residues are associated with several health problems in the human body such as acute allergic or toxic reactions, chronic toxic effects, and disturption of the natural balance of intestinal microflora as well as the emergence of antimicrobial resistance pathogenic bacteria. In order to determine the trace levels of antibiotics in the foodstuff, the development of rapid, sensitive and accurate analytical methods is necessary. Besides the great advances in the development of analytical instruments in recent years, sample preparation remains a critical step of any analytical procedure. Since food samples have complex and heterogeneous matrices, the sample preparation method can affect the accuracy, precision and overall performance of an analytical technique. Liquid-liquid extraction (LLE) is one of the most commonly used techniques for sample preparation which allows the selective concentration of target analytes in the aqueous samples. The aim of this study was to provide an updated overview of the recent trends and development in LLE techniques over the past 5 years. Different variations of this method such as hollow fiber liquid-phase microextraction, dispersive liquid-liquid microextraction, salting-out LLE, and aqueous two-phase system extraction are given in the present study. This review is focused on recent innovations and modifications in the LLE procedure which try to improve the efficiency and safety of this technique.

Azo dyes, in spite of being additives, are indeed an integral constituent of consumer goods with bio-therapeutic values. The addition of dyes is for consumer compliance which lends a sense of pleasing aesthetics to the consumption ready product, “a kind of placebo effect”. Consequently, imperative need of the hour is felt to quantify such azo dyes due to complications like skin allergic reactions, genotoxicity, and ADHD symptoms leading to carcinogenicity in the long run, by apt analytical technique. In the proposed research, a pivotal USP-HPTLC compliant, validated, digitized method with multiple wavelength detection using TLC silica gel 60 F254 aluminum plates is developed. Mobile phase comprising of n-butanol–isopropanol–25% ammonia (GR grade)–water (65:20:10:5, v/v) has been put to task and subjected to spectro-densitometric scan for their simultaneous screening and quantification. Validation was done as per ICH and US FDA guidelines incorporating the latest 21 CFR approved, digital image CAMAG visionCATS software. The results revealed that the proposed method was highly sensitive with good linear relationship R = 99.999% and RSD of 0.456%. Thus, the method may be employed as standard quality control tool in consumer goods for characterization of azo dyes, which are still in the spectrum of doubt especially given the opaque data that surfaces on their safety profiles.

Although flame atomic absorption spectrometry (FAAS) is hindered by its low sensitivity for most elements, it remains a widely used analytical technique in most laboratories. This study was aimed a...

A high-throughput single-cell analytical technique based on the microdroplet array integrated with the plasmon-enhanced-four-wave mixing (PE-FWM) imaging was developed, which is applicable for the highly sensitive and automatic assessment of the surface receptors of cells. The metal nanoprobes were prepared by simply decorating metal nanoparticles with capturing molecules (antibody or molecules with surface identification function). Owing to the multifrequency selection of lasers via resonating their plasmonic bands, these metal nanoprobes are highly recognizable under the FWM imaging and display high photostability above fluorescent dyes. This PE-FWM imaging technique shows superior to dark-field imaging due to almost no interference from off-resonant species and exhibits the antifade feature that is suitable for long-period cell monitoring. The automated processing of images is available for the analysis of cell heterogeneity according to the cell surface receptors. Emerging applications such as single-cell analysis, bioimaging, metabolite, and drug tracing offer many biological and medical possibilities with broad application prospects.

Non-targeted analysis (NTA) is a rapidly evolving analytical technique with numerous opportunities to improve and expand instrumental and data analysis methods. In this work, NTA was performed on eight synthetic mixtures containing 1264 unique chemical substances from the U.S. Environmental Protection Agency's Non-Targeted Analysis Collaborative Trial (ENTACT). These mixtures were analyzed by atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) using both positive and negative polarities for a total of four modes. Out of the 1264 ENTACT chemical substances, 1116 were detected in at least one ionization mode, 185 chemicals were detected using all four ionization modes, whereas 148 were not detected. Forty-four chemicals were detected only by APCI, and 181 were detected only by ESI. Molecular descriptors and physicochemical properties were used to assess which ionization type was preferred for a given compound. One ToxPrint substructure (naphthalene group) was found to be enriched in compounds only detected using APCI, and eight ToxPrints (e.g., several alcohol moieties) were enriched in compounds only detected using ESI. Examination of physicochemical parameters for ENTACT chemicals suggests that those with higher aqueous solubility preferentially ionized by ESI-. While ESI typically detects a larger number of compounds, APCI offers chromatograms with less background, fewer co-elutions, and additional chemical space coverage, suggesting both should be considered for broader coverage in future NTA research. Graphical abstract.

X-ray absorption spectroscopy (XAS) is one of the best techniques to obtain the information on the electronic and local structures of materials. In the last few decades, XAS becomes a common analytical technique for the investigation of solid oxide fuel cells and proton-conducting ceramic fuel cells. In particular, operando and/or advanced XAS measurements can be recently available with the increased accessibility of synchrotron radiation. In this article, recent trends of solid oxide fuel cell and proton-conducting ceramic fuel cell researches using XAS are overviewed.

The humankind is pretty dependent on food to control several biological processes into the organism. As the world population increases, the demand for foodstuffs follows the same trend claiming for a high food production situation. For this reason, a substantial amount of chemicals is used in agriculture and livestock husbandries every year, enhancing the likelihood of contaminated foodstuffs being commercialized. This outlook becomes a public health concern; thus, the governmental regulatory agencies impose laws to control the residues and contaminants in food matrices. Currently, one of the most important analytical techniques to perform it is LC. Despite its already recognized effectiveness, it is often time consuming and requires significant volumes of reagents, which are transformed into toxic waste. In this context, miniaturized LC modes emerge as a greener and more effective analytical technique. They have remarkable advantages, including higher sensitivity, lower sample amount, solvent and stationary phase requirements, and more natural coupling to MS. In this review, most of the critical characteristics of them are discussed, focusing on the benchtop instruments and their related analytical columns. Additionally, a discussion regarding the last 10 years of publications reporting miniaturized LC application for the analysis of natural and industrial food samples is categorized. The main chemical classes as applied in the crops are highlighted, including pesticides, veterinary drugs, and mycotoxins.

Surface-enhanced Raman scattering (SERS) is a powerful and sensitive technique for the detection of fingerprint sig-nals of molecules and for the investigation of a series of surface chemical reactions. Many studies introduced quantita-tive applications of SERS in various fields and several SERS methods have been implemented for each specific applica- tion, ranging in performance characteristics, analytes used, instruments, and analytical matrices. In general, very few methods have been validated according to international guidelines. As a consequence, the application of SERS in high-ly- regulated environments is still considered risky and the perception of a poorly reproducible and insufficiently robust analytical technique has persistently retarded its routine implementation. Collaborative trials are a type of interlabora-tory study (ILS) frequently performed to ascertain the quality of a single analytical method. The idea of an ILS of quan- tification with SERS arose within the framework of Working Group 1 (WG1) of the COST Action BM1401 Ra-man4Clinics32 in an effort to overcome the problematic perception of quantitative SERS methods. Here we report the first interlaboratory SERS study ever conducted, involving 15 laboratories and 41 researchers. In this study we tried to define a methodology to assess the reproducibility and trueness of a quantitative SERS method, and to compare differ- ent methods. In our opinion, this is a first important step toward a “standardization” process of SERS protocols, not proposed by a single laboratory but by a larger community.

Raman spectroscopy is a nondestructive and in situ analytical technique that could provide information on the chemical structure and structural ordering of carbonaceous materials. Based on theE(2g)symmetric stretching vibration mode in the aromatic layers (G band, ~1,580 cm(-1)) and the defect structure in graphite (D band, ~1,350 cm(-1)), Raman spectroscopy has been used extensively to characterize the structural features of carbonaceous matters since 1970. Coal is a complex organic compound made up mainly by carbon showing characteristic Raman bands. This article reviews the application of Raman spectroscopy for coal structure characterization under room temperature, to determine its chemical structure, crystallite size, coal rank, and combustion reactivity. Future research for collecting Raman spectra during coal pyrolysis at high temperatures is also discussed. The combination of high-temperature hot stage with Raman spectroscopy technology allows direct collection of Raman spectra at high temperature.

Thin layer chromatography–flame ionization detection (TLC–FID) is a versatile analytical technique that can be used for fast analysis of organic compounds. It has been implemented in past decades for the analysis of lipids and petrochemical products, but rarely in other fields. Despite the improvement in the latest Iatroscan model and the introduction of an automatic programmable sample spotter, this system is still struggling to gain acceptance in universities and major research laboratories. The reason behind this might be a lack of awareness on the potential application of this system to other fields of analytical chemistry. This review presents TLC–FID as a mature and reliable, state of the art technique that combines the separation power of TLC with FID as a universal detector, which can be applied to the analysis of a wide variety of organic compounds. Basic operational procedures and previous literature, including its potential for ultrafast analysis of commercial samples, are discussed in order to create awareness on the potentials of this piece of equipment to other fields.

The evolution of Raman spectroscopy into a useful analytical technique has been due, in part, to the development of inexpensive, compact instrumentation and advancements in methodologies that enhance Raman intensities. Surface enhanced Raman scattering (SERS) is a primary methodology for quantitative and low detection limit measurements. While a broad array of applications using solid SERS substrates have been demonstrated, in-solution SERS measurements are not as widely pursued. This work seeks to optimize the synthesis of gold nanostars (AuNS) as a colloidal SERS substrate for in-solution measurements using handheld instrumentation. The types and concentrations of two buffers typically used for AuNS synthesis are examined to optimize the SERS intensity of a chemisorbed Raman probe. The observed SERS intensity primarily depends on conditions that allow higher surface coverage of the probe. Conditions that result in AuNS aggregates are found to be most optimal for SERS, similar to other nanoparticle shapes. A method to quantitate methimazole, an anti-hormone pharmaceutical, in urine is developed and reported. The primary impact of this work is the demonstration of the combination of water dispersible substrates and handheld instrumentation for rapid and sensitive analytical measurements.

The use of veterinary drugs in medical treatments and in the livestock industry is a recurrent practice. When applied in subtherapeutic doses over prolonged times, they can also act as growth promoters. However, residues of these substances in foods present a risk to human health. Their analysis is thus important and can help guarantee consumer safety. The critical point in each analytical technique is the sample treatment and the analytical matrix complexity. The present manuscript summarizes the development, type of synthesis, characterization, and application of molecularly imprinted polymers in the separation, identification, and quantification techniques for the determination of veterinary drug residues in food samples in extraction, clean-up, isolation, and pre-concentration systems. Synthesized sorbents with specific recognition properties improve the interactions between the analytes and the polymeric sorbents, providing better analysis conditions and advantages in comparison with commercial sorbents in terms of high selectivity, analytical sensitivity, easy performance, and low cost analysis.

Fourier transform infrared spectroscopy (FTIR) is a widespread technique that can provide a chemical signature (fingerprints) of solid, liquid, or gas samples with a wide range of analytical applications. High-performance liquid chromatography (HPLC) is a leading analytical strategy for pharmaceutical analysis. Here we present a side-by-side comparison of the potential of these techniques for quantitative analysis of pharmaceutical active ingredient combinations in light of green analytical chemistry (GAC) principles. The methods were successfully applied for the analysis of ketoprofen (KTP)/hyoscine (HYS) and benzocaine (BENZ)/dextromethorphan HBr (DEX) in their binary mixtures and pharmaceutical preparations. In FTIR analysis, calibration models were constructed based on partial least squares regression (PLSR) with satisfactory regression coefficients (r2) of 0.9998, 0.9994, 0.9855, and 0.9895 for KTP, HYS, DEX, and BENZ, respectively, over a wide linearity range (10-100, 10-100, 5-75, and 10-100 μg mL-1) that covers the concentration ratios in the market samples. External validation using a validation set and internal validation using leave-one-out-cross-validation calculations were performed, and small root-mean-square-error-of-cross-validation (RMSECV) values were obtained indicating the good resolving power of the models. The same performance was obtained using the HPLC method for separation of the same mixtures with r2 equal to 0.9998, 0.9999, 0.9998, and 0.9998 over linear ranges of 50-1000, 10-200, 5-100, and 5-100 μg mL-1 for KTP, HYS, DEX, and BENZ, respectively. The HPLC methods were validated following ICH guidelines with good recovery percentages in the range of 98-100%. The statistical comparison of the FTIR and HPLC methods for analysis showed almost the same results with good applicability towards commercial dosage forms. Concerning the twelve GAC principles, a detailed comparison was performed to highlight the opportunities of each technique. FTIR-PLSR analysis showed superior performance as it allows for less solvent consumption, portability, less generated waste, short operating time, less operation cost, less energy consumption, and more operator safety and it is easily coupled with chemometric tools. Besides, FTIR is a direct analytical technique that can be used for the analysis of samples in all the physical forms (solid, liquid, and gas) without modifications.

Fentanyl and its analogs have been at the center of the opioid epidemic currently wreaking havoc in the United States. One major element in the opioid crisis is the growing number of clandestine fentanyl labs being reported by enforcement agencies. The development of new analytical methods for detecting and identifying fentanyl and its congeners is among the useful tools in our goal to limit the use of this dangerous family of narcotics. Herein we describe an analytical technique using surface-enhanced Raman spectroscopy (SERS) and a microfluidic device, for detecting fentanyl and two of its chemical precursors, despropionylfentanyl (4ANPP) and N-phenethyl-4-piperidinone (NPP). The vibrational spectra of this family of analytes are very similar, making them difficult to distinguish by traditional means. In addition to taking advantage of the sensitivity provided by SERS, we developed a chemometric approach utilizing a hierarchical partial least squares-discriminant analysis algorithm that allowed us to distinguish spectra that possess many similar features.

Relevant papers in the field of arsenic speciation analysis of environment samples published between 2004 and 2018 have been reviewed, with the focus on the analytical procedures according to the matrix investigated and the species researched. It emerged that suitable analytical methods have been developed for the identification and quantification of about fifty arsenic compounds in the main environmental matrices, including soil, sediments, terrestrial and marine organisms, atmospheric particulate and various types of natural waters. Various extraction/partitioning schemes have been applied, depending on the arsenic species (water- or lipid-soluble) and the matrix (biotic or abiotic), whereas water samples were generally analyzed directly. Liquid chromatography (LC) combined with inductively coupled plasma mass spectrometry was by far the analytical technique of choice, but a significant number of works also applied other couplings (LC to further atomic and mass spectrometry techniques) or X-ray methods. By the application of these procedures, a great amount of information on the occurrence of arsenic in the environment has been obtained, as well as the elucidation of the main processes involved and the discovery of new compounds, like arsenolipids and thio-arsenicals. However, remaining gaps and challenges still exist, both in the fundamental research on the origin and transformation of arsenic compounds in various environmental compartments and in the routine monitoring of toxic arsenic species. It is hence likely that the attempt to address these issues will drive the future research in the field.

Tricalcium phosphate Anhydrous Powder typically contains less than 10 ppm (mg/Kg) (w/w) manganese. This level can be determined utilizing Flame Atomic Absorption Spectrometer (AAS) and standard based on known standards. A number of analytical methods are presently used for the analysis of metals in the biochemical. The instrumental techniques available are Inductively Coupled Plasma (ICP/MS), X-Ray Fluorescence, UV-VIS Spectrophotometry, and Atomic Absorption Spectrometry. Flame AA has gained widespread acceptance as an analytical technique and is used for many applications. In this study, we have determined the amount of manganese metal present in Tricalcium Phosphate (TCP) using Flame Atomic Absorption Spectrophotometer. The method has high precision and accuracy. The percent recovery was found to be 99.8% for spiked sample. The results meet the requirement.

Graphene-enhanced Raman scattering (GERS) has attracted increasing attention from many scientists in recent years as a novel and potentially strong analytical technique since its discovery in 2010. GERS combines the ultra-high sensitivity and spectral analysis of the structural properties of many molecules found in surface-enhanced Raman scattering (SERS) and graphene simple sample processing and excellent uniformity. This facilitates a fast and very sensitive analysis of a wide range of analytes. Here, we present a new method for amino acid analysis based on the combination of drop coating deposition Raman (DCDR) and GERS. The potential of the method was evaluated in the analyses of Trp, Leu, Phe, and DOPA. Achievable limits of detection for all the studied amino acids are in tens of ng mL-1.

The development of a semi-automated and rapid analytical technique for dermatological analysis has become a key aim of many medical and commercial entities through greater awareness of people to skin health and its importance in the 21st century. We present a proof-of-concept methodology demonstrating the use of validated non-destructive, in-situ (Nuclear Magnetic Resonance Spectroscopy) NMR techniques for characterisation and quantitation of (Natural Moisturising Factor) NMF compounds and actives from topical formulations. This quantitation is crucial for appropriate diagnosis of atopic dermatitis severity due to its association with reduced NMF abundance. This study is the first to combine diffusion NMR, semi-automated quantitation and ex-vivo skin samples to measure NMF and permeation of actives. We have shown that diffusion NMR allows for resolution between formulation components through determination of self-diffusion coefficients. We also demonstrate how the metabolomics software chenomxtm can be used to identify and quantitate individual NMF components. We show comparable results to previous literature on NMF layers in the skin, alongside reinforcing findings on permeation enhancers and heat effects on transdermal delivery of actives and formulation components. The presented methodology has shown great potential as an effective non-destructive, fast and versatile technique for dermatological analysis of physiology and actives, with future hardware and software developments in NMR making the future of dermatological analysis via NMR very promising.

An effective analytical technique was developed for noble metals (NMs) determination, including Ru, Rh, Pd, Ir, Pt and Au, in solutions following geological sample digestion using reversible sorpti...

Rising concern about the use of non-permitted colourants, in common food items such as dals and green vegetables sold in Indian markets, have led to a demand for low-cost point-of-use chemical analysis tools. Conventional food-analysis techniques involving tedious sample preparation protocols are not suited for in-field applications. Surface Enhanced Raman Spectroscopy (SERS) is an analytical technique that is well-suited for point-of-use chemical analysis with molecular level detection capability, which can also serve as a quality assurance tool for businesses. Effective and rapid signal collection from a large-area sample within a field-setting using disposable, low-cost SERS substrates is a key challenge in implementing such a solution. Herein, we demonstrate the use of inkjet-printed thin films comprising of robust nanostructured-silver as flexible, paper-based SERS (P-SERS) swabs for the direct detection of Metanil Yellow (MY) from toor dal (yellow split pigeon peas) samples and Malachite Green (MG) from green peas and green chillies. The macroscopic uniformity of these thin-films in combination with a portable Raman spectrometer equipped with orbital raster scanning (ORS™) technology for signal collection results in an unprecedented precision (RSD ∼ 1.6%) upon characterizing samples saturated with Rhodamine-6G (R6G), a standard Raman probe. As several food-cleansing products have appeared in the marketplace, the adulterant removal efficacy of some commercially available ‘washes’ as well as products such as ‘ozoniser’, which was determined by SERS characterization of swabs before and after use, is also reported.

The inherently quantitative nature of nuclear magnetic resonance (NMR) spectroscopy is one of the most attractive aspects of this analytical technique. Quantitative NMR analyses have typically been limited to high-field (>1 T) applications. The aspects for quantitation at low magnetic fields (

Herbal medicine has become popular in recent years as an alternative medicine. The problem arises when herbal medicines contain an undeclared synthetic drug that is illegally added, since it is a natural product that does not contain any chemical drugs due to the potential cause of harmful effects. Supervision of herbal medicines is important to ensure that these herbal medicines are still safe to use. Thus, developing a reliable analytical technique for the determination of adulterated drugs in herbal medicine is gaining interest. This review aims to provide a recent analytical method that has been used within the past 5 years (2016–2021) for the determination of chemical adulterants in herbal medicine.

Direct analysis of complex samples is demonstrated by the at-line coupling of hollow fiber liquid-phase microextraction (HF-LPME) to capillary electrophoresis (CE). The hyphenation of the preparative and the analytical technique is achieved through a 3D-printed microextraction device with an HF located in a sample vial of a commercial CE instrument. The internal geometry of the device guides the CE separation capillary into the HF and the CE injection of the HF-LPME extract is performed directly from the HF lumen. The 3D-printing process ensures uniform dimensions of the devices, their constant position inside the sample vial, and excellent repeatability of the HF-LPME as well as the CE injection. The devices are cheap (∼0.01 €) and disposable, thus eliminating any possible sample-carryover, moreover, the at-line CE analysis of the extract is performed fully autonomously with no need for operator's intervention. The developed HF-LPME/CE-UV method is applied to the determination of acidic drugs in dried blood spot and wastewater samples and is characterized by excellent repeatability (RSD, 0.6–9.6%), linearity (r2, 0.9991–0.9999), enrichment (EF, 29–97), sensitivity (LOD, 0.2–3.4 μg/L), and sample throughput (7 samples/h). A further improvement of selected characteristics of the analytical method is achieved by the at-line coupling of HF-LPME to capillary isotachophoresis (ITP) with electrospray ionization-mass spectrometry (ESI-MS). The HF-LPME/ITP-ESI-MS system facilitates enhanced selectivity, matrix-free analytical signals, and up to 34-fold better sensitivity due to the use of ESI-MS detection and additional on-capillary ITP preconcentration of the HF-LPME extracts.

Laser-induced fluorescence (LIF) has been a valuable analytical technique since the 1970s that has only been made more useful through advances in other scientific fields such as biochemistry. Moreover, advances in laser and detector technology have seen a decrease in LIF detector costs and an increase in their ease of use. These changes have allowed for LIF technology to be widely adopted for various sensor designs in combination with advanced instruments. With advances in biochemistry necessitating the detection of complex metabolites, labelling with fluorescent chemical reagents may be necessary to improve detection sensitivity. Furthermore, advances made in fluorescent labeling technologies have allowed for the use of LIF in the detection of nanoparticles as well as for imaging techniques using nanoparticles as signal amplifiers. This technology has become invaluable in the detection of environmental pollutants, monitoring of biological metabolites, biological imaging, and cancer diagnosis, making it one of the most valuable analytical science techniques currently available.

Surface-enhanced Raman spectroscopy (SERS) is a powerful analytical technique capable of increasing the Raman signal of an analyte using specific nanostructures. The close contact between those nanostructures, usually a suspension of nanoparticles, and the molecule of interest produces an important exaltation of the intensity of the Raman signal. Even if the exaltation leads to an improvement of Raman spectroscopy sensitivity, the complexity of the SERS signal and the numbers of parameters to be controlled allow the use of SERS for detection rather than quantification. The aim of this study was to develop a robust discriminative and quantitative analysis in accordance with pharmaceutical standards. In this present work, we develop a discriminative and quantitative analysis based on the previous optimized parameters obtained by the design of experiments fixed for norepinephrine (NOR) and extended to epinephrine (EPI) which are two neurotransmitters with very similar structures. Studying the short evolution of the Raman signal intensity over time coupled with chemometric tools allowed the identification of outliers and their removal from the data set. The discriminant analysis showed an excellent separation of EPI and NOR. The comparative analysis of the data showed the superiority of the multivariate analysis after logarithmic transformation. The quantitative analysis allowed the development of robust quantification models from several gold nanoparticle batches with limits of quantification of 32 µg/mL for NOR and below 20 µg/mL for EPI even though no Raman signal is observable for such concentrations. This study improves SERS analysis over ultrasensitive detection for discrimination and quantification using a handheld Raman spectrometer.

Vaccines induce immunity by presenting disease antigens through several platforms ranging from individual protein subunits to whole viruses. Due to the large difference in antigen size, the analytical techniques employed for vaccine characterization are often platform-specific. A single, robust analytical technique capable of widespread, cross-platform use would be of great benefit and allow for comparisons across manufacturing processes. One method that spans the antigen mass range is charge detection mass spectrometry (CDMS). CDMS is a single-ion approach where the mass-to-charge ratio (m/z) and charge are measured simultaneously, allowing accurate mass distributions to be measured for heterogeneous analytes over a broad size range. In this work, CDMS was used to characterize the antigens from three classical multivalent vaccines, inactivated poliomyelitis vaccine (IPOL), RotaTeq, and Gardasil-9, directly from commercial samples. For each vaccine, the antigen purity was inspected, and in the whole virus vaccines, empty virus particles were detected. For IPOL, information on the extent of formaldehyde cross-linking was obtained. RotaTeq shows a narrow peak at 61.06 MDa. This is at a slightly lower mass than expected for the double-layer particle, suggesting that around 10 pentonal trimers are missing. For Gardasil-9, buffer exchange of the vaccine resulted in very broad mass distributions. However, removal of the virus-like particles from the aluminum adjuvant using a displacement reaction generated a spectrum with narrow peaks.

Inductively coupled plasma-mass spectrometry (ICP-MS) is a powerful analytical technique that can quantify elements of interest at parts-per-trillion concentrations. In this laboratory class, students performed ICP-MS analysis to quantify mercury concentration of standard reference material (SRM) 1947 (Lake Michigan fish tissue) and canned tuna from a local supermarket. These two samples were digested in two different matrices (HNO3/ H2O2 or HNO3/HCl/H2O2) and then analyzed using no-gas mode or helium mode with two different kinetic energy discrimination voltages (2V or 4V). The inclusion of HCl in the matrix produced more accurate results and stabilized mercury over the 8-day period after the digestion. Based on their analysis, the students were asked to draw their own conclusions about what they perceived to be the most accurate representation of the true mercury concentration of the tuna samples. This laboratory class provides students with a wide range of scientific concepts to explore such as method verification with SRM, kinetic energy discrimination, matrix effect, and trace metal stability over time.

The analytical technique DGT (Diffusive Gradients in Thin-films) is able to gain access to a wealth of information by carefully interpreting accumulation data from passive samplers with different configurations (i.e. different thicknesses of its constituent layers). A set of DGT devices were simultaneously deployed in solutions of Ni and nitrilotriacetic acid (NTA) of different concentrations to measure the availability of Ni in these solutions. Accumulations indicate that the availability of Ni depends on both the thickness of the resin and the thickness of the diffusive gel. In both cases, the lability degree increases as the thickness increases. As the formation of successive complexes (such as Ni(NTA)2) proceeds, the availability of the metal decreases, which is quantitatively explained by reducing the formulation to a case with only one complex, but with an effective dissociation rate constant that decreases as the concentration of NTA increases. Simple analytical expressions are reported to quantify the lability degree in the different DGT configurations. These results indicate that a set of different DGT devices can characterize the availability of a cation in a natural sample with uptake processes at different spatial or time scales. Alternatively, and from a more fundamental point of view, information on speciation, mobilities and labilities of the species present in natural samples can be obtained with a set of DGT configurations. Support from the Spanish Minister of Science and Innovation isgratefully acknowledged (Project PID2019-107033GB-C21). JSD ac-knowledges the University of Lleida for a fellowship PhD contract.

Exploratory mass spectrometry-based metabolomics generates a plethora of features in a single analysis. However, >85% of detected features are typically false positives due to inefficient elimination of chimeric signals and chemical noise not relevant for biological and clinical data interpretation. The data processing is considered a bottleneck to unravel the translational potential in metabolomics. Here, we describe a systematic workflow to refine exploratory metabolomics data and reduce reported false positives. We applied the feature filtering workflow in a case/control study exploring common variable immunodeficiency (CVID). In the first stage, features were detected from raw liquid chromatography-mass spectrometry data by XCMS Online processing, blank subtraction, and reproducibility assessment. Detected features were annotated in metabolomics databases to produce a list of tentative identifications. We scrutinized tentative identifications' physicochemical properties, comparing predicted and experimental reversed-phase liquid chromatography (LC) retention time. A prediction model used a linear regression of 42 retention indices with the cLogP ranging from -6 to 11. The LC retention time probes the physicochemical properties and effectively reduces the number of tentatively identified metabolites, which are further submitted to statistical analysis. We applied the retention time-based analytical feature filtering workflow to datasets from the Metabolomics Workbench (www.metabolomicsworkbench.org), demonstrating the broad applicability. A subset of tentatively identified metabolites significantly different in CVID patients was validated by MS/MS acquisition to confirm potential CVID biomarkers' structures and virtually eliminate false positives. Our exploratory metabolomics data processing workflow effectively removes false positives caused by the chemical background and chimeric signals inherent to the analytical technique. It reduced the number of tentatively identified metabolites by 88%, from initially detected 6940 features in XCMS to 839 tentative identifications and streamlined consequent statistical analysis and data interpretation.

We present a fully automated approach for quantitative compositional analysis of fermented beverages using benchtop nuclear magnetic resonance (NMR) spectroscopy. NMR spectroscopy, renowned for its applications in chemical structure elucidation, is gaining attention as a quantitative analytical technique due to its inherent linearity and the ability to obtain comprehensive quantitative information with a single simple experiment. Recently developed benchtop NMR spectrometers offer the quantitative capabilities of NMR to a wide range of potential users in industry, but their applicability has been limited by the reduced effective spectral resolution and the need for more advanced data processing. We address this problem with a model-based algorithm that hinges on the well-understood description of quantum mechanical phenomena in NMR spectroscopy. We demonstrate the effectiveness of our approach on a challenging problem of analysing the composition of wine and related fermented beverages - an important potential niche application of quantitative NMR. We successfully quantify more than 15 major components in the wine matrix and enable the quantification of species whose analysis is generally not possible with established methods. The average discrepancy of the obtained concentrations, when compared to the traditional methods of analysis, usually does not exceed 10% and is lower for the most abundant species (e.g. below 5% for ethanol).