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In this article, a comparison of ionization techniques is provided and discussed. Conventional liquid chromatography with an electrospray ionization source shows higher robustness and repeatability in comparison with liquid chromatography coupled with a coordination ion spray (CIS-MS) source using silver nitrate as the dopant. However, the higher sensitivity and possibility to collect more data in untargeted applications mean CIS-MS is emerging as an instrument used in specific applications. During this research, the limit of detection (LOD) for GHRP-2 and GHRP-6 was established at 0.2 ng/mL, and the lower limit of quantification (LLOQ) was 0.5 ng/mL for CIS-MS. For conventional ESI-MS combined with solid-phase extraction on weak cation exchange columns, the limit of detection was found to be 1 ng/mL, and the lower limit of quantification was 2 ng/mL. [ABSTRACT FROM AUTHOR]

The selective analysis of 4-nitrophenol (4-NP) from water samples using on-line solid-phase extraction (SPE) coupled to HPLC system was studied. The β-cyclodextrin bonded silica (CDS) was utilized as the selective sorbent. Using 100 ml of sample solution spiked with 4-nitrophenol and other six phenols (Ph) in double distilled water, the sorbent showed strong capacity in adsorbing 4-nitrophenol and the recovery was 104% with the detection limit of 0.017 μg/l. The selectivity was investigated by utilizing a washing step with acetonitrile after preconcentration and only 4-nitrophenol was detected with the recovery of 99%. Donghu lake (Wuhan, China) water sample was used to test the on-line SPE-HPLC system and 4-nitrophenol was selectively extracted with the recovery obtained as 90%. [Copyright &y& Elsevier]

In this study, magnetic solid phase extraction coupled with in - situ derivatization (MSPE-ISD) was established for the determination of hexanal and heptanal in human urine. 2,4-Dinitrophenylhydrazine (DNPH) was used as the derivatization reagent that was adsorbed onto the surface of magnetite/silica/poly(methacrylic acid-co-ethylene glycol dimethacrylate) (Fe 3 O 4 /SiO 2 /P(MAA-co-EGDMA)). And then simultaneous extraction and derivatization of the aldehydes were performed on the DNPH-adsorbed Fe 3 O 4 /SiO 2 /P(MAA-co-EGDMA). The simple, rapid and sensitive determination of hexanal and heptanal can be accomplished within 9 min. Under optimized conditions, the limits of detection (LODs) were 1.7 and 2.5 nmol/L for hexanal and heptanal, respectively. The relative recoveries ranged from 72.8% to 91.4% with the intra- and inter-day relative standard deviations (RSDs) being less than 9.6%. Furthermore, the proposed method was successfully applied to determine endogenous hexanal and heptanal in human urine from healthy persons and lung cancer patients. The results showed the higher concentrations of hexanal and heptanal were observed in lung cancer patients compared to healthy controls. Thus, the developed MSPE-ISD method is suitable for the determination of aldehydes in urines. [ABSTRACT FROM AUTHOR]

Background Brassinosteriods (BRs) are a group of important phytohormones that have major effects on plant growth and development. To fully elucidate the function of BRs, a sensitive BR assay is required. However, most of the previously reported methods are tedious and time-consuming due to multiple pretreatment steps. Therefore, it is of great significance to develop a method to increase the throughput and detection sensitivity of BR analysis. Results We established a novel analytical method of BRs based on magnetic solid phase extraction (MSPE) combined with in situ derivatization (ISD). TiO2-coated magnetic hollow mesoporous silica spere(TiO2/MHMSS) was served as a double identity- a microextraction sorbent and "microreactor" for the capture and derivatization of BRs in sequence. BRs were first extracted onto TiO2/MHMSS through hydrophilic interaction. The BR-adsorbed TiO2/MHMSS was then employed as a "microreactor" for the derivatization of BRs with 4-(N,N-dimethyamino)phenylboronic acid (DMAPBA). The MSPE-ISD method was simple and fast, which could be accomplished within 10 min. Furthermore, the derivatives of BRs showed better MS response because they were incorporated with tertiary amino groups. Uniquely, endogenous BRs were detected in only 100 mg fresh weight plant tissue. Conclusion Our proposed MSPE-ISD method for the determination of endogenous BRs is rapid and sensitive. It can be applied to the analysis of endogenous BRs in 100 mg fresh plant tissue (Brassica napus L. (B. napus L)). The proposed strategy for plant sample preparation may be extended to develop analytical methods for determination of a wide range of analytes with poor MS response in other complex sample matrices. [ABSTRACT FROM AUTHOR]

In this study, magnetic polypyrrole nanowires (mPPYs) were fabricated via a simple co-mixing method based on an 'aggregation-wrap' mechanism. The polypyrrole (PPy) nanowires were synthesized by in situ chemical oxidative polymerization using cetyltrimethylammonium bromide as the 'soft template' and the magnetic nanoparticles (MNPs) prepared using solvothermal methods. Typically, when these two nanomaterials were vortically mixed in a solvent, the MNPs were wrapped into the PPy nanowire networks that formed during the aggregation process, leading to the formation of mPPYs which can be separated from the solvent rapidly and conveniently by a magnet. Due to the better permeability, good adsorption ability, and magnetic separability of the resultant material, mPPYs were applied for the enrichment of 11 pesticides including organophosphorus, organochlorine, and pyrethroid using magnetic solid phase extraction (MSPE) to test their feasibility in sample preparation. Several parameters affecting the extraction efficiency were investigated, and under the optimized conditions, a simple and effective method for the determination of pesticide residues was established by coupling with gas chromatography/mass spectrometry (GC/MS) analysis. The whole pretreatment process was rapid and can be accomplished within 15 min. The linearity range of the proposed method was 0.2-10 μg/L, with correlation coefficients ( R) of 0.995-0.999; the limits of quantification for the target compounds were in the range of 0.09-0.29 μg/L. In addition, an acceptable reproducibility was achieved by evaluating the intra- and inter-day precisions with relative standard deviations of less than 14 and 16 %, respectively. Finally, the established MSPE-GC/MS method was successfully applied for the determination of pesticide residues in beverage teas, juices, and environmental water samples. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: A 2-acrylamido-2-methyl-1-propanesulfonic acid-co-ethylene glycol dimethacrylate (Fe3O4/SiO2/P(AMPS-co-EGDMA)) copolymer was prepared and used as a magnetic solid phase extraction (MSPE) medium for recovery of endogenous cytokinins (CKs) from plant extracts. This magnetic porous polymer was characterized by electron microscopy, nitrogen sorption experiments, elemental analysis and Fourier-transformed infrared spectroscopy. It was demonstrated to have high extraction capacity toward CKs in plants due to its specificity, surface area and porous structure. Coupled with hydrophilic interaction chromatography–tandem mass spectrometry (HILIC–MS/MS), a rapid, simple, and effective MSPE–HILIC–MS/MS analytical method for the quantitative analysis of endogenous CKs in Oryza sativa (O. sativa) roots was successfully established. Good linearities were obtained for all CKs investigated with correlation coefficients (R 2)>0.9975. The results showed that LODs (S/N=3) were ranged from 0.18 to 3.65pgmL−1. Reproducibility of the method was obtained with intra-day and inter-day relative standard deviations (RSDs) less than 16.1% and the recoveries in plant samples ranged from 72.8% to 115.5%. Finally, the MSPE–HILIC–MS/MS method was applied to several plant samples, and the amounts of endogenous CKs in O. sativa roots, leaves and Arabidopsis thaliana (A. thaliana) were successfully determined. [Copyright &y& Elsevier]

Abstract: In this paper, two phenothiazine bonded silica (PTZ-Si) sorbents were prepared and used as sorbents of solid-phase extraction (SPE) for the determination of nitrobenzene compounds in environmental water samples by gas chromatography–mass spectrometry (GC–MS). Different synthesis routes were proposed to obtain high bonded amount of PTZ on the surface of silica gel. PTZ molecule was derived to its amino or acyl chloride derivatives for reacting with isocyanate or amino silane coupling agent, which was further reacted with the surface silanol groups of silica gel to obtain the PTZ-Si sorbents. The resultant PTZ-Si sorbents were characterized by nitrogen sorption porosimetry (NSP), Fourier transform infrared spectroscopy (FT-IR) and elemental analysis (EA) to assure the successful bonding of PTZ on the surface of silica gel. Then the PTZ-Si sorbents were served as SPE sorbents for the enrichment of nitrobenzene compounds. Several parameters affecting the extraction performance were investigated. Under the optimized conditions, the proposed method was applied to the analysis of six nitrobenzene compounds in environmental water samples. Good linearities were obtained for all nitrobenzene compounds with R 2 larger than 0.9958. The limits of detection were found to be in the range of 0.06–0.3ng/mL. The method recoveries of nitrobenzene compounds spiked in water samples were from 71.4% to 124.3%, with relative standard deviations (RSDs) less than 10.1%. [Copyright &y& Elsevier]

Abstract: The silica nanoparticle (SiO2 NP)-deposited capillary fabricated by liquid phase deposition (LPD) was bonded by 3-(triethoxysilyl) propyl methacrylate and then modified with poly(N-isopropylacrylamide) (PNIPAAm) by polymerization. The resulting PNIPAAm modified SiO2 NP-deposited capillary was applied to in-tube solid-phase microextraction coupled to high-performance liquid chromatography (in-tube SPME–HPLC). To investigate the extraction performance of the prepared capillary, diethylstilbestrol (DES) with moderate polarity was selected as the model analyte. Results demonstrate that PNIPAAm modified SiO2 NP-deposited capillary exhibited obvious temperature responsive character. Finally, the PNIPAAm modified SiO2 NP-deposited capillary was applied to the analysis of three synthetical estrogens from milk samples. The detection limit of the method was found to be in the range 1.2–2.2ng/g, and recovery was 71.7–98.9% with relative standard deviations in the range of 2.8–12.6%. [Copyright &y& Elsevier]

Abstract: A hybrid organic–inorganic silica monolith with hydrophobic and strong cation-exchange functional groups was prepared and used as a sorbent for micro-solid phase extraction (micro-SPE). The hybrid silica monolith functionalized with octyl and thiol groups was conveniently synthesized by hydrolysis and polycondensation of a mixture of tetraethoxysilane (TEOS), n-octyltriethoxysilane (C8-TEOS) and 3-mercaptopropyltrimethoxysilane (MPTMS) via a two-step catalytic sol–gel process. Due to the favorable chemical reactivity of mercapto pendant moieties, the obtained hybrid monolith was oxidized using hydrogen peroxide (30%, w/w) to yield sulfonic acid groups, which provided strong cation-exchange sites. The obtained hybrid monolith was characterized by diffused infrared spectroscopy, elemental analysis, scanning electron microscopy and mercury intrusion porosimetry. The results show that the resulting monolith contains much higher carbon (31.6%) and sulfur (4.8%) contents than traditionally bonded silica materials. The extraction performance of the hybrid monolith was evaluated using sulfonamides as testing analytes by micro-SPE on-line coupled to HPLC. The results show that the hybrid monolith with hydrophobic and strong cation-exchange functional groups exhibits high extraction efficiency towards the testing analytes. The column-to-column RSD values were 1.3–9.8% for the extraction of SAs investigated. The extraction performance of the hybrid silica monolith remained practically unchanged after treated with acid (pH 1.0) and basic solutions (pH 10.5). Finally, the application of the hybrid monolith was demonstrated by micro-SPE of sulfonamide residues from milk followed by HPLC–UV analysis. The limits of detection (S/N=3) for eight SAs were found to be 1.0–3.0ng/mL in milk. The recoveries of eight SAs spiked in milk sample ranged from 80.2% to 115.6%, with relative standard deviations less than 11.8%. [Copyright &y& Elsevier]

Abstract: A simple, rapid, and sensitive method is presented to determine seven trace quinolone antibacterials simultaneously in milk, egg, chicken and fish. This method is based on the combination of polymer monolith in-tube solid-phase microextraction with liquid chromatography and electrospray ionization quadrupole time-of-flight mass spectrometry (LC/ESI-QTOF-MS). LC/ESI-QTOF-MS offers the capability of unequivocal identification of target compounds from complex matrices, as well as the possibility of quantitation at low-level concentrations in real samples. The extraction was performed with a poly(methacrylic acid-ethylene glycol dimethacrylate) monolithic column. Under the optimized extraction conditions, good extraction efficiencies for the targets were obtained with no matrix interference in the subsequent LC/ESI-QTOF-MS. Good linearities were obtained for seven quinolones with the correlation coefficients (R) above 0.9951. The limits of detection (S/N =3) for seven quinolones were found to be 0.3–1.2ng/g in egg, 0.2–3.0ng/mL in milk, 0.2–0.7ng/g in chicken and 0.2–1.0ng/g in fish. The recoveries of quinolones spiked in four different matrices ranged from 80.2 to 115.0%, with relative standard deviations less than 14.5%. The developed method was applied for the determination of quinolone residues in animal-producing food, and the positive samples were confirmed with high number of identification points (IPs) according to the IP system defined by the European Union (Commission Decision 2002/657/EC). [Copyright &y& Elsevier]

Abstract: An octyl-functionalized hybrid silica monolithic column was developed for in-tube solid-phase microextraction (SPME) to perform on-line preconcentration coupled to capillary high-performance liquid chromatography (μHPLC) analysis. A hybrid silica monolithic column functionalized with octyl groups was conveniently synthesized by a two-step acid/base-catalyzed hydrolysis/co-condensation of tetraethoxysilane (TEOS) and n-octyltriethoxysilane (C8-TEOS). The size of through-pores as well as the carbon content can be adjusted by changing the ratio of TEOS to C8-TEOS in the polymerization mixture. The extraction characteristics of the monolithic column prepared under optimized fabrication conditions were studied by using polycyclic aromatic hydrocarbons (PAHs) as the analytes. The sample volume that could be injected into the system was increased up to 1mL with simultaneous increase of column efficiency, when hybrid silica monolithic column was used as a precolumn. Good linear calibration curves (R >0.999) were obtained, and the limits of detection (signal-to-noise ratio, S/N=3) for the analytes were found to be between 2.4 and 8.1ng/mL with a UV absorbance detector, which are 299–456 times lower than those obtained without preconcentration. The column-to-column RSD values were 1.3–8.0% for recoveries of PAHs investigated. [Copyright &y& Elsevier]

The detection of 25-hydroxyvitamin D (25OHD) from dried blood spots (DBS) has been widely studied. However, the existing pretreatment methods suffer from limitations in terms of throughput (usually exceeding 2 h), complexity (involving liquid-liquid extraction or solid-phase extraction), and contamination (including multiple steps of organic solvent evaporation). We first released 25OHD from DBS samples by 50% acetonitrile solution through ultrasonication. Subsequently, the cold-induced phase separation technique was introduced for in-situ concentration and purification. Afterward, the PTAD derivatization of 25OHD was performed directly, profiting from the high acetonitrile content in the concentrated solution. In the end, the resulting solution was submitted to LC-MS/MS for quantification. The established LC-MS/MS methodology possessed favorable analytical performance, possessing lower limit of quantification of 1 ng/mL pointing to plasma, accuracy of 86.8–110.1% and imprecision of 5.4–16.8%. Method comparison with plasma samples demonstrated that over 93% of the detections met the acceptance limit for cross-validation of ±20%. The novel sample preparation can be finished within 15 min and eliminated the traditional steps of extraction and organic solvent evaporation. Based on this high-throughput, reliable and applicable LC-MS/MS method, the detection of 25OHD in DBS samples can be better achieved for clinical patients and researchers with relevant demands. [Display omitted] • A highly applicable LC-MS/MS method was developed for 25OHD detection in DBS. • Extraction and PTAD derivatization of 25OHD can be completed within 15 min. • The new method can provide consistent results as the plasma-based method. [ABSTRACT FROM AUTHOR]

For the first time, boronate affinity chromatography and metal oxide affinity chromatography mechanisms for cis-diol-compounds extraction are simultaneously realized on a single material, termed borated zirconia. This material was prepared by hydrolyzing zirconium butoxide with boric acid under non-aqueous environment. The diameter of formed particles is around 200 nm. By extracting catechol under different pH conditions or with phosphate ion competition, the dual affinity mechanisms of borated zirconia are confirmed. Benefiting from such unique feature, borated zirconia can function well under neutral condition. By using borated zirconia for dispersive solid phase extraction, specific capture of cis-diol-containing catecholamines, including epinephrine (E), norepinephrine (NE) and dopamine (DA), was achieved. A reliable LC-MS/MS method was established and validated for quantification of these target analytes in plasma samples after derivatisation with benzoyl chloride. The linear ranges are 0.010–0.200 ng·mL−1 for E and DA, and 0.050–1.000 ng·mL−1 for NE. The limits of quantification are 0.008, 0.020 and 0.004 ng·mL−1 for E, NE and DA respectively. By analyzing samples from healthy volunteers and schizophrenia patients, the plasma concentrations of E, NE and DA were found to be higher for the latter. [ABSTRACT FROM AUTHOR]

Both DNA cytosine methylation (5-methyl-2′-deoxycytidine, m5dC) and RNA cytosine methylation (5-methylcytidine, m5rC) are important epigenetic marks that play regulatory roles in diverse biological processes. m5dC and m5rC can be further oxidized by the ten-eleven translocation (TET) proteins to form 5-hydroxymethyl-2′-deoxycytidine (hm5dC) and 5-hydroxymethylcytidine (hm5rC), respectively. 2′- O -methyl-5-hydroxymethylcytidine (hm5rCm) was recently also identified as a second oxidative metabolite of m5rC in RNA. Previous studies showed that the dysregulation of cytidine modifications in both DNA and RNA are closely related to a variety of human diseases. These cytidine modifications are generally excreted from cell into urine. If these cytidine modifications exhibit specific features related to certain diseases, determination of the cytidine modifications in urine could be utilized as non-invasive diagnostic of diseases. Here, we established a solid-phase extraction in combination with liquid chromatography-mass spectrometry (LC-MS/MS) analysis for simultaneous detection of these cytidine modifications in human urine samples. The developed method enabled the distinct detection of these cytidine modifications. We reported, for the first time, the presence of hm5rCm in human urine. Furthermore, we found that compared to the healthy controls, the contents of hm5dC, hm5rC, and hm5rCm showed significant increases in urine samples of cancer patients, including lymphoma patients, gastric cancer patients, and esophageal cancer patients. This study indicates that the urinary hydroxylmethylation modifications of hm5dC, hm5rC, and hm5rCm may serve as potential indicator of cancers. Image 1 • We established a SPE in combination with LC-ESI-MS/MS analytical method. • The method enables simultaneous detection of cytidine modifications in urine. • We reported, for the first time, the presence of hm5rCm in human urine. • Cytidine modifications significantly increased in urine samples of cancer patients. • Cytidine modifications in urine may serve as potential indicator of cancers. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel strategy was developed to identify BZD metabolites. • Eleven BZD metabolites were discovered in pig serum for the first time. • More comprehensive BZD metabolic pathways were presented. • The new metabolites may act as biomarkers of BZDs drug in related animal food. Abstract Benzimidazoles (BZDs) are widely used veterinary drugs in the domestic food-producing animals, resulting in the metabolism of BZDs and the harmful metabolites residues in some foods. However, some BZD metabolites are unknown and so it is important to discover new metabolites to expand detection targets. For these reasons, a sensitive and selective strategy was designed to identify BZD metabolites in the serum of pigs after oral administration of albendazole, fenbendazole and thiabendazole, respectively. Nickel oxide nanoparticle-deposited silica (SiO 2 @NiO) composite was used for the enrichment and purification of BZD compounds. High-performance liquid chromatography coupled with precursor ion scan-mass spectrometry (LC-PIS-MS) and high resolution MS/MS analysis (HR-MS/MS) was employed for the BZDs metabolic profiles characterization and metabolites detection. Finally, 18 BZD metabolites were identified, among which 11 metabolites were discovered in pig serum for the first time. Besides, more comprehensive BZD metabolic pathways were presented. [ABSTRACT FROM AUTHOR]

In the present study, 1-naphthol (1-NAP) and 2-naphthol (2-NAP) were extracted from urine by magnetic solid phase extraction (MSPE) based on magnetic graphitized carbon black (M-Fe 3 O 4 @C) and analyzed by high performance liquid chromatography with ultraviolet detection (HPLC-UV). M-Fe 3 O 4 @C was fabricated by simple physical blending method, briefly, the graphitized carbon black (GCB) and Fe 3 O 4 nanoparticles were directly mixed and ground in a mortar. In this process, Fe 3 O 4 were physically wrapped and adhered to GCB forming the M-Fe 3 O 4 @C which can be easily collected and isolated from sample solution by a magnet. The prepared M-Fe 3 O 4 @C was used as MSPE adsorbent for isolation of 1-NAP and 2-NAP from urine via hydrophobic and π − π interaction. Several parameters which would affect the extraction efficiency were investigated. Under the optimal condition, the whole pretreatment process can be accomplished within 15 min. The linearity range of the proposed method was 10–5000 μg/L with satisfactory correlation coefficients (R2) of 0.9982–0.9983. The limits of detection (LOD) were 0.9 μg/L for 1-NAP and 1.1 μg/L for 2-NAP. The recoveries in spiked urine were in the range of 78.2–103%, with the RSDs <12.9% (intra-day, n = 6) and 9.9% (inter-day, n = 3). Finally, the established method was successfully applied to detect naphthols in college student volunteers and the workers of petrochemical company. • A new method for the analysis of naphthols in urine was developed based on M-Fe 3 O 4 @C extraction. • M-Fe 3 O 4 @C was fabricated by simple mix and grind without chemical reaction procedures. • The whole sample pretreatment process can be accomplished within 15 min by simple vortex. • The method was proven to be simple, rapid and effective. [ABSTRACT FROM AUTHOR]

Highlights • A novel magnetic sorbent (Fe 3 O 4 @ANDS) was fabricated via Lewis acid/base reaction. • A new method for analysis of trans-resveratrol in peanut oils was developed by HPLC-UV detection. • The sensitivity was comparative to the reported methods using LC-MS/MS detection. • Fe 3 O 4 @ANDS possesses great potential for extracting polar analytes from oil matrix. Abstract In the present study, a rapid and effective method based on alendronate sodium grafted mesoporous magnetic nanoparticle (Fe 3 O 4 @ANDS) extraction for the determination of trans-resveratrol (TRA) in peanut oils was developed by coupling with HPLC-UV detection. The Fe 3 O 4 @ANDS was prepared via Lewis acid/base interaction which was simply carried out in mild aqueous condition without the using of organic solvent. The resultant Fe 3 O 4 @ANDS encompassed amino group on its surface, and it was employed as magnetic solid-phase extraction adsorbent for purification and enrichment of TRA from peanut oils through hydrogen bond interaction. Under the optimized conditions, the whole pretreatment process could be accomplished within 10 min without time-consuming concentrated and reconstituted process. The linearity range of the proposed method was 1–10,000 ng/g with satisfactory correlation coefficient (R2) of 0.9992. The recoveries in spiked oil samples were in the range of 78.6–118.9% with the RSDs less than 3.3% (intra-day) and 15.2% (inter-day). The limit of detection for TRA in peanut oils was 0.3 ng/g which was comparative to the reported methods by using LC-MS/MS detection. Finally, the established method was successfully applied to the analysis of TRA in several peanut oils with different brands from local market as well as other kinds of vegetable oils. [ABSTRACT FROM AUTHOR]

Tailor-made chitosan fiber was prepared via hydrothermal treatment to serve as a micro-solid phase extraction (micro-SPE) sorbent for the analysis of petroleum acids (PAs) in crude oils. Chitosan fiber, which is commercial and cheap, has a diameter of about 10 μm and a length of a few centimeters. The fibrous property of the sorbent enables the micro-SPE to deal with viscous crude oil samples because of the low back-pressure during extraction, while the abundant hydroxyl groups and amino groups on the surface of chitosan fiber can provide high density of specific sites for adsorption of PAs. Moreover, it was found that hydrothermal treatment at certain conditions could tune the surface properties of chitosan fiber, leading to significant improvement of the capacity of the fiber in adsorption of PAs. Using hydrothermally treated chitosan fiber as sorbent, the micro-SPE was applied to the determination of PAs in crude oils, with the advantages of easy-operation, rapidness and high sensitivity (the limits of detection range from 0.7 ng/g to 5.4 ng/g). Furthermore, coupled with comprehensive two dimensional gas chromatography-mass spectrometry (GC × GC MS), the treated chitosan fiber packed micro-SPE method showed a great potential for comprehensive profiling of PAs in crude oils. [ABSTRACT FROM AUTHOR]

Low-molecular-weight thiols play important roles in a variety of pathological processes and are closely associated with a wide range of diseases. In this study, a selective and sensitive method was developed for the simultaneous determination of all the 7 thiols occurring in the transsulfuration pathway (Cysteine (Cys), homocysteine (Hcys), glutathione (GSH), N -acetylcysteine (Nac), cysteinylglycine (CysGly), glutamylcysteine (GluCys) and cysteamine (CA)) in human serum by in - vitro stable isotope labeling - dispersive solid phase extraction - liquid chromatography - tandem mass spectrometry analysis (IL-DSPE-LC-MS/MS). In the proposed method, a pair of stable isotope-labeling reagents, BQB ( ω -bromoacetonylquinolinium bromide) and BQB- D 7 , were utilized to label thiols in human serum samples and thiol standards, respectively. The BQB labeled thiols which carry a positive charge were extracted and purified with C 8 -SO 3 H-based DSPE followed by LC-MS/MS analysis. Good linearities for 7 thiols occurring in the transsulfuration pathway were obtained with the coefficient of determination ( R 2 ) >0.9901. The limits of detection (LODs) were in the range of 0.7–6.0 nmol/L. The method was further applied to investigate the contents change of 7 thiols in human serum samples of type 2 diabetes mellitus (T2DM) patients and breast cancer (BC) patients. The results showed that the contents of these thiols occurring in the transsulfuration pathway significantly changed and were highly diseases-related. In addition, partial least squares discriminant analysis (PLS-DA) suggested excellent classification performance between patients and healthy controls. The findings indicated that these significantly changed thiols occurring in the transsulfuration pathway in T2DM patients and BC patients might serve as the indicator for the diagnosis of T2DM and BC. Taken together, the developed IL-DSPE-LC-MS/MS method provides a promising tool for the sensitive analysis of thiols from complex biological samples, which may promote the in-depth investigation of the functions of thiols. [ABSTRACT FROM AUTHOR]

In this study, we developed a strategy for profiling of thiols and aldehydes in beer samples by stable isotope labeling-solid phase extraction-liquid chromatography-double precursor ion scan/double neutral loss scan-mass spectrometry analysis (SIL-SPE-LC-DPIS/DNLS-MS). A pair of isotope reagents ( ω -bromoacetonylquinolinium bromide, BQB; ω -bromoacetonylquinolinium- d 7 bromide, BQB- d 7 ) were used to label thiols; while for the aldehydes, a pair of isotope reagents (4-(2-(trimethylammonio) ethoxy) benzenaminium halide, 4-APC; 4-(2-(trimethylammonio) ethoxy) benzenaminium halide- d 4 , 4-APC- d 4 ) were used. The labeled thiols and aldehydes were extracted and purified with solid-phase extraction, respectively, followed by LC–MS analysis. Using the proposed SIL-SPE-LC-DPIS/DNLS-MS methods, 76 thiol and 25 aldehyde candidates were found in beer. Furthermore, we established SIL-SPE-LC-MRM-MS methods for the relative quantitation of thiols and aldehydes in different beer samples. The results showed that the contents of thiols and aldehydes are closely related to the brands and origins of beers. [ABSTRACT FROM AUTHOR]

Recently, a new class of endogenous lipids, branched fatty acid esters of hydroxy fatty acids (FAHFAs), was discovered with anti-diabetic and anti-inflammatory effects in mammals. FAHFAs attracted increasing attention because of their critical physiological function. However, accurate quantitation of FAHFAs is still a challenge due to their high structure similarity and low abundance in biological samples. Herein, we developed a highly sensitive method for the determination of 16 FAHFAs (PAHSAs, OAHSAs, SAHSAs and POHSAs) in biological samples by coupling strong anion exchange solid phase extraction (SAX-SPE) with chemical labeling assisted ultra-high performance liquid chromatography/mass spectrometry (SAX-SPE-CL-UHPLC/MS). In the developed method, SAX-SPE was employed to selectively enrich and purify FAHFAs from biological samples. And then a pair of isotope labeling reagents, 2-dimethylaminoethylamine (DMED) and d 4 -DMED were used to label the purified samples and standard FAHFAs, respectively. The labeled samples were mixed and further subjected to UHPLC/MS analysis. Our results demonstrated that the detection sensitivities of FAHFAs increased by 7–72 folds upon DMED labeling and the limits of detections (LODs) of labeled FAHFAs ranged from 0.01 to 0.14 pg. Moreover, a good separation of FAHFAs isomers was achieved on C18 column in a UHPLC system and all FAHFAs could be analyzed in 20 min with sharp peak shape. The established method provided substantial sensitivity, high specificity, and broad linear dynamic range (3 orders of magnitude). Using this method, we successfully measured the contents and distribution of FAHFAs in rat white adipose, lung, kidney, thymus, liver and heart tissues. The results showed that 7 FAHFAs (13-, 12-, 9-, 5-PAHSA, 13-, 12- and 9-SAHSA) were observed in different tissues of rat. In addition, we successfully detected the above 7 FAHFAs in human serum samples; and among the 7 FAHFAs, 13-, 9-PAHSA, 13- and 12-SAHSA were found remarkably decreased in human breast cancer serum. The proposed method could be successfully applied for the detection of FAHFAs in various biological samples, which will facilitate the understanding of the physiological functions of FAHFAs. [ABSTRACT FROM AUTHOR]

Aflatoxins (AFs) are highly toxic, mutagenic, carcinogenic, and teratogenic secondary metabolites produced by the toxigenic fungi Aspergillus flavus and Aspergillus parasiticus . AFs tend to contaminate a wide range of foods which is a serious and recurring food safety problem worldwide. Currently, immunoaffinity chromatography (IAC) has become the most conventional sample clean-up method for determining AFs in foodstuffs. However, IAC method is limited in the large-scale food analysis because it requires the use of expensive disposable cartridges and the IA procedure is time-consuming. Herein, to achieve the cost-effective determination of AFs in edible oils, we developed a promising solid-phase extraction (SPE) method based on commercially available humic acid-bonded silica (HAS) sorbent, followed by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) analysis. In HAS-SPE, AFs can be captured by the HAS sorbent with both hydrophobic and hydrophilic interactions, whereas the oil matrix was captured only with the hydrophobic interactions. The oil matrix can be sufficiently washed off with isopropanol, while the AFs were still retained on the SPE packing, thus achieving selective extraction of AFs and clean-up of oil matrices. Under the optimal conditions of HAS-SPE, satisfactory recoveries ranging from 82% to 106% for four AFs (B 1 , B 2 , G 1 , and G 2 ) were achieved in various oil matrices, containing blended oil, tea oil, rapeseed oil, peanut oil, sunflower seed oil, corn oil, blended olive oil, rice oil, soybean oil, and sesame oil. Only minor matrix effects ranging from 99% to 105% for four AFs were observed. Moreover, the LODs of AFs between 0.012 and 0.035 μg/kg completely meet the regulatory levels fixed by the EU, China or other countries. The methodology was further validated for assaying the naturally contaminated peanut oils, and consistent results between the HAS-SPE and the referenced IAC were obtained. In addition, HAS-SPE can directly treat diluted oil sample without liquid-liquid extraction and is automatable, thus making it simple and convenient for the large-scale determination of AFs in edible oils. Using this method, we successfully detected four AFs in the naturally contaminated peanut oils, which is, to the best of our knowledge, the first report about the determination of AFs in edible oils using HA-based SPE. [ABSTRACT FROM AUTHOR]

Polycystic ovary syndrome (PCOS) is the most common cause of anovulatory infertility. The pathogenesis of PCOS remains unclear and early diagnosis of PCOS is challenging. Follicular fluid provides a unique window in the critical processes during oocyte and follicular maturation, and the metabolic level of follicular fluid has important impact on the developmental potential of oocytes and subsequent embryos. Previous studies demonstrated some modified ribonucleosides in biological fluids were diseases related metabolites. In this respect, analysis of endogenous modified ribonucleosides in follicular fluids will facilitate the investigation of follicular development. Here, we developed a strategy for determination of ribose conjugates from follicular fluid using metal oxide-based dispersive solid-phase extraction (DSPE) coupled with liquid chromatography-multiple reaction monitoring-mass spectrometry analysis (DSPE-LC-MRM-MS/MS). Cerium dioxide (CeO 2 ) was used to selectively recognize and capture cis -diol containing ribose conjugates from complex biological samples under basic environment. The trapped ribose conjugates were then easily released under acidic environment. The results showed that 50 potential ribose conjugates were detected in follicular fluid by the developed DSPE-LC-MRM-MS/MS method. We then further investigated the contents change of the detected ribose conjugates in follicular fluid from PCOS patients. The results indicated that the follicular fluid from healthy controls and PCOS patients can be clearly differentiated with the partial least squares-discriminate analysis (PLS-DA) based on the detected ribose conjugates. In addition, the contents of 8 ribose conjugates were significantly different between PCOS patients and healthy controls, which could potentially serve as the indicator of PCOS. [ABSTRACT FROM AUTHOR]

A fully automated in-tube solid phase microextraction/liquid chromatography-post column derivatization-mass spectrometry (in-tube SPME/LC-PCD-MS) method was developed for the analysis of urinary hexanal and heptanal. Online in-tube SPME enabled effective enrichment of the low level aldehydes and elimination of matrix interferences. PCD could be simply realized by mixing the LC elute and hydroxylamine hydrochloride (HAHC) solution with just a tee. The peak broadening and loss in separation efficiency associated with post column dead-volume could be ignored and even completely eliminated by employing suitable PCD configuration. What’s more, HAHC is commercially available and quite cheap, and shows no contaminations to MS. The entire procedure, including the extraction of aldehydes by in-tube SPME, LC separation, post column derivatization and MS detection were integrated together and completely automated, offering competitive advantages in terms of rapidity, economy, reproducibility and simplicity. The developed protocol was then successfully performed to determine lung cancer biomarkers (hexanal, heptanal) levels in urine samples. [ABSTRACT FROM AUTHOR]

Background: Phytohormones play crucial roles in almost all stages of plant growth and development. Accurate and simultaneous determination of multiple phytohormones enabled us to better understand the physiological functions and the regulatory networks of phytohormones. However, simultaneous determination of multiple phytohormones in plant is still a challenge due to their low concentrations, structural and chemical diversity, and complex matrix of plant tissues. Therefore, development of a simple and selective method for the simultaneous determination of multiple phytohormones is highly needed. Results: We developed a clean-up strategy for profiling of multiple phytohormones, which can overcome the challenge of structural and chemical diversity. By using a one-step dispersive solid-phase extraction (DSPE) combined with UPLC-MS/MS, 54 phytohormones including auxins, ABA, SA, JA, GAs and CKs were simultaneously analyzed from a single rice sample extract. Using the developed method, we investigated the spatiotemporal distribution of phytohormones in rice. The profiling of various tissues of rice at different growth stages revealed the complexity of metabolic regulation and allocations of phytohormone species. Conclusion: A rapid one-step method was developed for the simultaneous analysis of six groups of phytohormones, including cytokinins, auxins, salicylic acid, jasmonates, abscisic acid and gibberellins in a single run, using UPLC-ESI-MS/MS. The proposed method was successfully applied to investigate spatiotemporal distribution of multiple phytohormones in rice. The spatiotemporal information obtained may be helpful for better understanding of phytohormones functions throughout life cycle of rice when integrated into transcriptome and other omics data. [ABSTRACT FROM AUTHOR]

More than 140 modified ribonucleosides have been identified in RNA. Determination of endogenous modified ribonucleosides in biological fluids may serve as non-invasive disease diagnostic strategy. However, detection of the modified ribonucleosides in biological fluids is challenging, especially for the low abundant modified ribonucleosides due to the serious matrix interferences of biological fluids. Here, we developed a facile preparation strategy and successfully synthesized zirconium oxide-silica (ZrO 2 /SiO 2 ) composite capillary monolithic column that exhibited excellent performance for the selective enrichment of cis -diol-containing compounds. Compared with the boronate-based affinity monolith, the ZrO 2 /SiO 2 monolith showed ∼2 orders of magnitude higher extraction capacity and can be used under physiological pH (pH 6.5–7.5). Using the prepared ZrO 2 /SiO 2 composite monolith as the trapping column and reversed-phase C18 column as the analytical column, we further established an online solid-phase microextraction (SPME) in combination with liquid chromatography-mass spectrometry (online SPME-LC–MS/MS) analysis for the comprehensive profiling of ribonucleosides modification in human urine. Our results showed that 68 cis -diol-containing ribosylated compounds were identified in human urine, which is, to the best of our knowledge, the highest numbers of cis -diol-containing compounds were determined in a single analysis. It is worth noting that four modified ribonucleosides were discovered in the human urine for the first time. In addition, the quantification results from the pooled urine samples showed that compared to healthy controls, the contents of sixteen ribose conjugates in the urine of gastric cancer, eleven in esophagus cancer and seven in lymphoma increased more than two folds. Among these ribose conjugates, four ribose conjugates increased more than two folds in both gastric cancer and esophagus cancer; three ribose conjugates increased more than two folds in both gastric cancer and lymphoma; one ribose conjugate increased more than two folds in both esophagus cancer and lymphoma. The developed analytical method provides a good platform to study the modified ribonucleosides in human body fluids. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are a group of ubiquitous environmental contaminants raising worldwide concerns due to their carcinogenic effects. In this study, 1-hydroxypyrene (1-OHP, the most widely used biomarker of internal dose of PAHs exposure) in undiluted human urine samples (10 mL) was selectively enriched by polypyrrole-coated Fe 3 O 4 magnetite nanocomposites (termed as Fe 3 O 4 @Ppy, 1 mg) and then directly eluted by the electrospraying solvent (acetone/benzene/acetic acid (v/v/v, 90/10/1); 100 uL) biased with −3.5 kV to produce the deprotonated 1-OHP anions for mass spectrometric analysis. The method established here significantly improved the current performance for detection of urinary 1-OHP, providing the speed for a single sample analysis within 4 min, the limits of detection (LOD) of 0.0001 μg L −1 , the linear response range of 0.001–5.000 μg L −1 (R 2 = 0.9994), recovery rates of 90.6–96.1%, and relative standard deviation (RSD, n = 6) values between 2.9% and 8.0%. Human samples including raw human urine collected from 10 healthy volunteers (5 smokers and 5 nonsmokers) and 7 lung cancer patients have been successfully analyzed, showing that magnetic solid-phase extraction (MSPE) coupled with internal extractive electrospray ionization mass spectrometry (iEESI-MS) is an alternative strategy for high throughput quantitative detection of urinary 1-OHP for health risk assessment of PAHs exposure. [ABSTRACT FROM AUTHOR]

In this study, a sequential magnetic solid phase extraction followed by in situ derivatization/desorption method was proposed for the fast, selective and sensitive determination of brassinosteroids (BRs) in plant tissues. Magnetic sorbent for quick, easy, cheap, effective, rugged and safe method (mQuEChERS) and polymer(4-vinylphenylboronic acid- co -ethylene glycol dimethacrylate) coated Fe 3 O 4 @SiO 2 (p(4-VPBA- co -EGDMA) coated Fe 3 O 4 @SiO 2 ) were prepared and characterized. Using them as sorbents, pigments and hydrophilic interferents were firstly removed from plant extract by mQuEChERS, and then endogenous BRs were selectively enriched by p(4-VPBA- co -EGDMA) coated Fe 3 O 4 @SiO 2 through boronate affinity interaction. After loading BRs on p(4-VPBA- co -EGDMA) coated Fe 3 O 4 @SiO 2 , instead of directly eluting free BRs, the adsorbed BRs were released by adding 4-( N,N -dimethyamino)phenylboronic acid (4-DMAPBA) solution for in situ derivatizaiton/desorption of BRs based on a transesterification reaction between the boronate moieties of p(4-VPBA- co -EGDMA) coated Fe 3 O 4 @SiO 2 and 4-DMAPBA, finally the resultant solution was submitted to LC–MS/MS for quantification. The whole procedure of the sequential MSPE could be accomplished within 1 h, and the matrix effect to MS signal after the sample pretreatment was estimated to be in the range of 93.0–97.4%. The established method provided broad linear dynamics ranges (1.0–100.0 pg/mL) with correlation coefficients (R) >0.9978, substantial sensitivity (limits of detection ranged from 0.27 to 1.29 pg/mL), high reproducibility (intra-day and inter-day relative standard deviations (RSDs) less than 14.8%) and satisfactory accuracy (recoveries ranged from 74.0%–116.6%). Furthermore, endogenous BRs were successfully detected in one flower of Brassica napus L. (22.5–542.7 pg/g fresh weight) and other plant tissues (13.7–289.8 pg/g fresh weight). [ABSTRACT FROM AUTHOR]

In this study, we proposed a method to fabricate magnetic carbon nitride (CN) nanosheets by simple physical blending. Low-cost CN nanosheets prepared by urea possessed a highly π-conjugated structure; therefore the obtained composites were employed as magnetic solid-phase extraction (MSPE) sorbent for extraction of polycyclic aromatic hydrocarbons (PAHs) in edible oil samples. Moreover, sample pre-treatment time could be carried out within 10 min. Thus, a simple and cheap method for the analysis of PAHs in edible oil samples was established by coupling magnetic CN nanosheets-based MSPE with gas chromatography-mass spectrometry (GC/MS) analysis. Limits of quantitation (LOQs) for eight PAHs ranged from 0.4 to 0.9 ng/g. The intra- and inter-day relative standard deviations (RSDs) were less than 15.0%. The recoveries of PAHs for spiked soybean oil samples ranged from 91.0% to 124.1%, with RSDs of less than 10.2%. Taken together, the proposed method offers a simple and cost-effective option for the convenient analysis of PAHs in oil samples. [ABSTRACT FROM AUTHOR]

A newly improved one-pot method, based on “thiol-ene” click chemistry and sol–gel approach in microemulsion system, was developed for the preparation of C 8 /PO(OH) 2 -silica hybrid monolithic capillary column. The prepared monolith possesses large specific surface area, narrow mesopore size distribution and high column efficiency. The monolithic column was demonstrated to have cation exchange/reversed-phase (CX/RP) mixed-mode retention for analytes on nano-liquid chromatography (nano-LC). On the basis of the developed nano-LC system with MS detector coupled to pipette tip solid phase extraction (PT-SPE) and derivatization process, we then realized simultaneous determination of 10 gibberellins (GAs) with low limits of detection (LODs, 0.003–0.025 ng/mL). Furthermore, 6 endogenous GAs in only 5 mg rice leaves (fresh weight) were successfully detected and quantified. The developed PT-SPE-nano-LC–MS strategy may offer promising applications in the determination of low abundant bioactive molecules from complex matrix. [ABSTRACT FROM AUTHOR]

Ambient ionization techniques show good potential in rapid analysis of target compounds. However, a direct application of these ambient ionization techniques for the determination of analytes in a complex matrix is difficult due to the matrix interference and ion suppression. To resolve this problem, here we developed a strategy by coupling magnetic solid phase extraction (MSPE) with desorption corona beam ionization (DCBI)-mass spectrometry (MS). As a proof of concept, the pyrrole-coated Fe3O4 magnetic nanoparticles (Fe3O4@Ppy) were prepared and used for the extraction of antidepressants. After extraction, the Fe3O4@Ppy with trapped antidepressants was then directly subjected to DCBI-MS analysis with the aid of a homemade magnetic glass capillary. As the MSPE process is rapid and the direct DCBI-MS analysis does not need solvent desorption or chromatographic separation processes, the overall analysis can be completed within 3 min. The proposed MSPE-DCBI-MS method was then successfully used to determine antidepressants in human urine and plasma. The calibration curves were obtained in the range of 0.005–0.5 μg mL−1 for urine and 0.02–1 μg mL−1 for plasma with reasonable linearity (R2 ＞ 0.951). The limits of detection of three antidepressants were in the range of 0.2–1 ng mL−1 for urine and 2–5 ng mL−1 for plasma. Acceptable reproducibility for rapid analysis was achieved with relative standard deviations less than 19.1% and the relative recoveries were 85.2–118.7%. Taken together, the developed MSPE-DCBI-MS strategy offers a powerful capacity for rapid analysis of target compounds in a complex matrix, which would greatly expand the applications of ambient ionization techniques with plentiful magnetic sorbents. [ABSTRACT FROM AUTHOR]

In the present study, humic acids (HAs) were applied as both a matrix for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and an adsorbent of magnetic solid phase extraction (MSPE) for the first time. As natural macromolecule compounds, HAs are inherently highly functionalized and contain laser energy absorbing–transferring aromatic structures. This special molecular structure made HAs a good candidate for use as a MALDI matrix in small molecule analysis. At the same time, due to its good adsorption ability, HAs was prepared as MSPE adsorbent via a simple co-mixing method, in which the commercially available HAs were directly mixed with Fe 3 O 4 magnetic nanoparticles (MNPs) in a mortar and grinded evenly and completely. In this process, MNPs were physically wrapped and adhered to tiny HAs leading to the formation of magnetic HAs (MHAs). To verify the bi-function of the MHAs, Rhodamine B (RdB) was chosen as model compound. Our results show that the combination of MHAs-based MSPE and MALDI-TOF-MS can provide a rapid and sensitive method for the determination of RdB in chili oil. The whole analytical procedure could be completed within 30 min for simultaneous determination of more than 20 samples, and the limit of quantitation for RdB was found to be 0.02 μg/g. The recoveries in chili oil were in the range 73.8–81.5% with the RSDs less than 21.3% (intraday) and 20.3% (interday). The proposed strategy has potential applications for high-throughput analysis of small molecules in complex samples. [ABSTRACT FROM AUTHOR]

Phytohormones, a collection of signal small molecules with various structures, regulate a series of physiological processes of plants. For instance, they regulate the growth and development, response to biotic and abiotic stresses. Quantification of trace endogenous phytohormones is essential to elucidate their molecular mechanisms in response to stresses. However, the structural and chemical diversity of phytohormones make it difficult to purify and enrich multiple phytohormones in one-step. In the current study, a method was developed to comprehensively profile phytohormones, including 8 cytokinins (CKs), indole-3-acetic acid (IAA), abscisic acid (ABA), jasmonic acid (JA) and 10 gibberellins (GAs) by Fe 3 O 4 @TiO 2 -based magnetic solid-phase extraction coupled with ultra-performance liquid chromatography-electrospray tandem mass spectrometry (Fe 3 O 4 @TiO 2 -based MSPE-UPLC-MS/MS). In the proposed method, the phytohormones in the acetonitrile extract of plant tissues were captured and purified by one-step MSPE using Fe 3 O 4 @TiO 2 as a sorbent prior to UPLC-MS/MS analysis. The sensitivity, accuracy and reproducibility of the proposed analytical method were demonstrated to satisfy the profiling of multiple phytohormones in plant tissue. We then further used the Fe 3 O 4 @TiO 2 -based MSPE-UPLC-MS/MS method to explore the change of phytohormones in rice under Cd stress. The results showed that CKs, IAA, ABA, JA and biological active GAs all increased under Cd stress, suggesting that these phytohormones may take part in response to Cd stress. The study may promote the further understanding of the physiological functions of phytohormones in response to Cd stress. [ABSTRACT FROM AUTHOR]

Some modified ribonucleosides in biological fluids have been evaluated as cancer-related metabolites. Detection of endogenous modified ribonucleosides in biological fluids may serve as a noninvasive cancers diagnostic method. However, determination of modified ribonucleosides is still challenging because of their low abundance and serious matrix interferences in biological fluids. Here, we developed a novel strategy for comprehensive profiling of ribose conjugates from biological fluids using metal oxide-based dispersive solid-phase extraction (DSPE) followed with in vitro stable isotope labeling and double neutral loss scan-mass spectrometry analysis (DSPE-SIL-LC-DNLS-MS). Cerium dioxide (CeO2) was used to selectively recognize and capture ribose conjugates from complex biological samples under basic environment. The enriched ribose conjugates were subsequently labeled with a pair of isotope labeling reagents (acetone and acetone-d<6). The glucosidic bond of acetone labeled ribose conjugates is readily ruptured, and the generated ribose that carries an isotope tag can be lost as a neutral fragment under collision induced dissociation (CID). Since the light (acetone) and heavy (acetone-d6) labeled compounds have the same chemical structures and can generate different neutral loss fragments (NL 172 and 178 Da), it is therefore highly convenient to profile ribose conjugates by double neutral loss scan mode in mass spectrometry analysis. In this respect, the light and heavy labeled compounds were ionized at the same condition but recorded separately on MS spectra, which can significantly improve the detection specificity and facilitate the identification of ribose conjugates. Using the developed DSPE-SIL-LC-DNLS-MS strategy, we profiled the ribose conjugates in human urine, and 49 ribose conjugates were readily identified, among which 7 ribose conjugates exhibited significant contents change between healthy controls and lymphoma patients. The DSPE-SIL-LC-DNLS-MS strategy combines the selective enrichment, stable isotope labeling, and double neutral loss scan - MS analysis, which therefore can efficiently minimize false positive results, facilitate the relative quantification, and notably increase the numbers of identified ribose conjugates in biological fluids samples. Taken together, this study established a promising strategy for the effective profiling of urinary modified ribonucleosides, and simultaneous evaluation of the contents change of multiple modified ribonucleosides should provide more accurate and conclusive results for the use of urinary modified ribonucleosides as indicators of cancers. [ABSTRACT FROM AUTHOR]

Phytohormones, a collection of signal small molecules with various structures, regulate a series of physiological processes of plants. For instance, they regulate the growth and development, response to biotic and abiotic stresses. Quantification of trace endogenous phytohormones is essential to elucidate their molecular mechanisms in response to stresses. However, the structural and chemical diversity of phytohormones make it difficult to purify and enrich multiple phytohormones in one-step. In the current study, a method was developed to comprehensively profile phytohormones, including 8 cytokinins (CKs), indole-3-acetic acid (IAA), abscisic acid (ABA), jasmonic acid (JA) and 10 gibberellins (GAs) by Fe 3 O 4 @TiO 2 -based magnetic solid-phase extraction coupled with ultra-performance liquid chromatography-electrospray tandem mass spectrometry (Fe 3 O 4 @TiO 2 -based MSPE-UPLC-MS/MS). In the proposed method, the phytohormones in the acetonitrile extract of plant tissues were captured and purified by one-step MSPE using Fe 3 O 4 @TiO 2 as a sorbent prior to UPLC-MS/MS analysis. The sensitivity, accuracy and reproducibility of the proposed analytical method were demonstrated to satisfy the profiling of multiple phytohormones in plant tissue. We then further used the Fe 3 O 4 @TiO 2 -based MSPE-UPLC-MS/MS method to explore the change of phytohormones in rice under Cd stress. The results showed that CKs, IAA, ABA, JA and biological active GAs all increased under Cd stress, suggesting that these phytohormones may take part in response to Cd stress. The study may promote the further understanding of the physiological functions of phytohormones in response to Cd stress. [ABSTRACT FROM AUTHOR]

A simple method was developed for the preparation of ordered mesoporous silica-carbon composite nanofibers (OMSCFs). The OMSCFs exhibited high carbon content, continuously long fibrous properties, uniform accessible mesopores, and a large surface area. The OMSCFs were also found to have ion-exchange capacity. On the basis of the size-exclusion effect of the mesopores and mixed-mode hydrophobic/ion-exchange interactions, the OMSCFs were applied for rapid enrichment of endogenous peptides by using a miniaturized solid-phase extraction format. The adsorption mechanism was studied, and the eluting solution was optimized with standard peptide/protein solutions and protein digests. Employing a successive three-step elution strategy, followed by LC-MS/MS analysis, led to excellent performance with this approach in the extraction and prefractionation of peptides from human serum. [ABSTRACT FROM AUTHOR]

A novel in-syringe dispersive solid phase extraction (dSPE) system using electrospun silica fibers as adsorbents has been developed in the current work. A few milligrams of electrospun silica fibers were incubated in sample solution in the barrel of a syringe for microextraction assisted by vortex. Due to the benefit of dispersion and the high mass transfer rate of the sub-microscale electrospun silica fibers, the extraction equilibrium was achieved in a very short time (less than 1 min). Moreover, thanks to the long fibrous properties of electrospun fibers, the separation of the adsorbent from sample solution was easily achieved by pushing out the sample solution which therefore simplified the sample pretreatment procedure. Besides, the analytical throughput was largely increased by using a multi-syringe plate to perform the extraction experiment. The performance of the in-syringe dSPE device was evaluated by extraction of endogenous cytokinins from plant tissue samples based on the hydrophilic interaction. Six endogenous cytokinins in 20 mg of Oryza sativa L. (O. sativa) leaves were successfully determined under optimized conditions using in-syringe dSPE combined with liquid chromatography-mass spectrometry analysis. The results demonstrated that the in-syringe dSPE method was a rapid and high-throughput strategy for the extraction of target compounds, which has great potential in microscale sample pretreatment using electrospun fibers. [ABSTRACT FROM AUTHOR]

In this article, pollen grains were for the first time used as a hydrophilic solid-phase extraction (HILIC-SPE) sorbent for the determination of 16 plant growth regulators (PGRs) in fruits and vegetables. Fourier transform infrared spectroscopy (FT-IR), scanning electronic microscopy (SEM) and nitrogen sorption porosimetry (NSP) were used to investigate the chemical structure and the surface properties of the pollen grains. Pollen grains exhibited an excellent adsorption capacity for some polar compounds due to their particular functional groups. Several parameters influencing extraction performance were investigated. A green and simple HILIC-SPE-method using pollen grain cartridge for purification of fruit and vegetable extractions, followed by ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry (UHPLC-MS/MS) was established. Good linear relationships were obtained for 16 PGRs with correlation coefficients ( R ) above 0.9980. The limits of detection (LODs) of 16 PGRs in cucumber were in the range of 0.01–1.10 μg·kg −1 . Reproducibility of the method was evaluated by intra-day and inter-day precisions with relative standard deviations (RSDs), which were less than 14.4%. We successfully applied this methodology to analyze 16 PGRs in 8 different kinds of fruits and vegetables. The recoveries from samples spiked with 16 PGRs were from 80.5% to 119.2%, with relative standard deviations less than 15.0%. [ABSTRACT FROM AUTHOR]

A simple, rapid and sensitive method based on magnetic solid phase extraction (MSPE) coupled with in situ derivatization (ISD) was developed for the determination of endogenous acidic phytohormones in rice leaves by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis. With this method, acidic phytohormones were extracted onto the surface of a TiO2/magnetic hollow mesoporous silica sphere (MHMSS) through hydrophilic interaction, and then in situ derivatization was performed by the subsequent addition of 3-bromoactonyltrimethylammonium bromide (BTA). Thus, the process integrated extraction, purification, and derivatization into one step. Additionally, the permanent positively charged moiety from BTA significantly improved the ionization efficiencies of the acidic phytohormones. Several parameters affecting the efficiencies of the extraction, derivatization, and desorption were evaluated. The signal intensities of acidic phytohormones increased by 2 to 481 fold after treatment with MSPE-ISD. Under the optimized conditions, several endogenous acidic phytohormones, including GA4, GA9, GA20, JA, IAA, and ABA, were identified and quantified in rice leaves by the MSPE-ISD method. The limits of detection (LODs) were in the range of 1.03–91.21 pg mL−1. The relative recoveries ranged from 71.6–112.8%, with the intra- and interday relative standard deviations (RSDs) being less than 14.9% and 16.2%, respectively. Taken together, the proposed method provides a novel approach of combining magnetic solid phase extraction and in situ derivatization for the highly sensitive determination of endogenous acidic phytohormones. [ABSTRACT FROM AUTHOR]

The metal oxide affinity chromatography (MOAC) materials have been extensively used for extraction of phosphate compounds in the past decade. Actually, some of these materials also possess adsorption affinity towards cis-diol-containing compounds, which was seldom explored in separation field so far. Here we present the proof-of-concept study to evaluate the feasibility of expanding MOAC for specific capture of cis-diol biomolecules. Benefitting from the high commercialisation of the metal oxide materials, such MOAC strategy possesses several advantages, like synthesis-free, low cost and high expandability. Firstly, the recognition of adenosine against 2′-deoxyadenosine was performed using zirconium oxide and cerium oxide, two typical commercial MOAC materials. The results showed that efficient adsorption and elution could be achieved easily by pH switching from basic to acidic. The isotherm curves demonstrated the adsorption process fitted well with Freundlich isotherm model and was spontaneous at room temperature (ΔG0 < 0) with an exothermic nature (ΔH0 < 0). Afterwards, the highly efficient and selective enrichment of various model cis-diol biomolecules, including ribonucleosides, glycopeptides and glycoproteins, was achieved using this MOAC strategy. Finally, the endogenous ribonucleosides and modified ribonucleosides were successfully purified from human urine sample, which demonstrated the potential application of MOAC materials in the enrichment of target compounds from complex biological samples. Besides the excellent performance of extraction for cis-diol-containing compounds, equally important is that these materials are commercially available with low cost, which makes the MOAC a promising strategy for the study of cis-diol biomolecules in metabolomics and proteomics. [ABSTRACT FROM AUTHOR]

Highlights: [•] A simple and high-throughput method was developed for the determination of endogenous CKs. [•] CKs were enriched with one-step MSPE procedure. [•] 10 endogenous CKs can be detected in 50mg Oryza sativa sample. [•] 40 samples could be analyzed within one day. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel method to prepare magnetic MIPs was developed. [•] Magnetic MIPs were successfully used in proposed MIMSPE method. [•] The proposed method was less time-consuming (within 4.5min). [•] Other MIPs can be selected as raw materials in magnetic MIPs synthesis. [ABSTRACT FROM AUTHOR]

Highlights: [•] A simple and efficient method was developed for the determination endogenous CKs. [•] CKs were purified by one-step HILIC SPE based on hydrophilic interaction. [•] Endogenous CKs can be quantified from only 20mg plant sample. [ABSTRACT FROM AUTHOR]

A novel TiO2-based SPE strategy was developed for eliminating normal ribonucleosides before mass spectrometry (MS) analysis of 2'-deoxynucleosides and 2'-O-modified ribonucleosides. The chromatographic research for the retention behavior of ribonucleosides and 2'-deoxynucleosides on TiO2 materials was investigated using TiO2 separation column. The results indicated a specific affinity interaction mechanism between TiO2 and cis-diol-containing ribonucleosides, and the interaction was proved effective even under a wide range of pH conditions and salt concentrations. Benefiting from these features, a TiO2-based solid phase extraction (SPE) method was developed for highly efficient elimination of RNA contamination from genomic DNA. Compared with the widely used enzymatic digestion method, the proposed TiO2-based SPE method showed much more efficiency for the removal of RNA as well as provided high recoveries for the 2'-deoxynucleosides. In addition, the sample processing time is dramatically shortened using the TiO2-based SPE method (5 min) compared to the traditional enzymatic digestion method (12 h). Finally, the purification of 2'-O-methylated ribonucleosides from RNA was successfully achieved in HeLa cells by the TiO2-based SPE method, which provided a proof-of-concept for the purification of relevant modified ribonucleosides from bulky normal ribonucleosides. Taken together, this strategy developed in the current study offers a promising option to purify 2'-deoxynucleosides/2'-O-modified ribonucleosides for their sensitive and accurate determination by eliminating normal ribonucleosides in biological samples. [ABSTRACT FROM AUTHOR]

Highlights: [•] A facile hydrothermal strategy was developed for the synthesis of SiO2@rGO. [•] The SiO2@rGO has large rGO immobilized amount. [•] The SiO2@rGO shows remarkable adsorption capacity toward CPs and peptides. [•] A superior recovery could be obtained compared to C18, GCB and CNTs. [•] The SiO2@rGO was used to determine CPs in water samples. [Copyright &y& Elsevier]

Background: Brassinosteriods (BRs), a group of important phytohormones, have various effects on plant growth and development. However, their physiological functions in plants have not been fully understood to date. Endogenous BRs in plant tissue are extremely low and the elucidation of BRs functions relies on sensitive detection method. Reported methods for the determination of BRs required large amount of plant tissue, tedious pretreatment process, and were lack of selectivity. Therefore, development of a simple and selective method for the sensitive quantification of BRs is highly needed. Results: We established a pretreatment method of BRs in plant tissues by employing double layered solid phase extraction (DL/SPE) combined with boronate affinity polymer monolith microextraction (BA/PMME). After the initial depigmentation with DL/SPE cartridge, BA/PMME was employed to selectively extract BRs from sample matrix. Uniquely, most sample matrix was successfully removed by BA monolith purification. Using this method, BRs was determined by liquid chromatography-mass spectrometry (LC-MS). Endogenous active BRs could be detected in only 1 g fresh weigh (FW) leaves or 0.5 g FW flower tissues. Conclusion: A DL/SPE-BA/PMME pretreatment method for the determination of endogenous brassinosteroids in plant tissues was developed and validated. The proposed method was sensitive and selective. Besides, it may be further developed for the determination of other BRs including their precursors and conjugates. [ABSTRACT FROM AUTHOR]

Abstract: In current study, a substrateless graphene fiber was successfully prepared by a simple hydrothermal strategy and used as solid-phase microextraction (SPME) sorbent. Five organochlorine pesticides (OCPs) were employed as model analytes to evaluate the performance of as-prepared graphene fiber. The results showed that the graphene fiber exhibited higher extraction efficiencies, higher thermal stability (up to 310°C), better reproducibility, and longer service life (more than 180 times reuse) than commercial fibers. In addition, the method for the determination of OCPs was proposed by coupling headspace (HS)-SPME technique with gas chromatography/electron capture detector (HS-SPME-GC/ECD). The proposed HS-SPME-GC/ECD method showed low limits of detection (0.83–11.5ng/L), wide linear dynamic ranges (more than 2 orders of magnitude), and acceptable reproducibility (RSD<10.9%). Finally, the proposed method was successfully applied to the analysis of OCPs in environmental water samples with good recoveries (81–121%) and satisfactory precisions (RSD<9%). [Copyright &y& Elsevier]

Abstract: In current study, we developed a highly sensitive method for the quantitative profiling of acidic phytohormones. Tandem solid-phase extraction (SPE) and liquid–liquid extraction (LLE) was employed to efficiently purify acidic phytohormones, which were further derived by 3-bromoactonyltrimethylammonium bromide (BTA) to increase the ionization efficiency in electrospray ionization-mass spectrometry detection. Additionally, fifteen BTA-derived acidic phytohormones, including ten gibberellins (GAs), were well separated with a salt gradient on poly(methacrylic acid-co-ethylene glycol dimethacrylate) (MAA-co-EDMA) monolithic column. By employing online trapping system, the signal intensities of the analytes were significantly improved. The limits of detection (LODs, Signal/Noise=3) of targeted phytohormones ranged from 1.05 to 122.4pg/mL, which allowed the highly sensitive determination of low abundant acidic phytohormones with tiny amount plant sample. Good reproducibility was obtained by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) less than 10.9 and 11.9%, respectively. Recoveries of the target analytes from spiked rice leave samples ranged from 88.3 to 104.3%. By employing the method developed here, we were able to simultaneously determine 11 endogenous acidic phytohormones from only 5mg of rice leave sample, which dramatically decreased the required sample amount (three orders of magnitude lower) for the profiling of low abundant acidic phytohormones compared to previous reports. Taken together, the method provided a good solution for the highly sensitive and quantitative profiling of endogenous acidic phytohormones. [Copyright &y& Elsevier]

Abstract: In the present work, we developed a novel dispersive microextraction technique by combining the advantages of liquid-phase microextraction (LPME) and magnetic solid-phase extraction (MSPE). In this method, trace amount of water directly absorbed on bare Fe3O4 to form water-coated Fe3O4 (W-Fe3O4) and rapid extraction can be achieved while W-Fe3O4 dispersed in the sample solution. The analyte adsorbed W-Fe3O4 can be easily collected and isolated from sample solution by application of a magnet. It was worth noting that in the proposed method water was used as extractant and Fe3O4 served as the supporter and retriever of water. The performance of the method was evaluated by extraction of 3-monochloropropane-1,2-diol (3-MCPD) from edible oils. The extracted 3-MCPD was then derived by a silylanization reagent (1-trimethylsilylimidazole) before gas chromatography–mass spectrometry (GC–MS) analysis. Several parameters that affected the extraction and derivatization efficiency were investigated. Our results showed that the limit of detection for 3-MCPD was 1.1ng/g. The recoveries in spiked oil samples were in the range of 70.0–104.9% with the RSDs less than 5.6% (intra-day) and 6.4% (inter-day). Taken together, the simple, rapid and cost-effective method developed in current study, offers a potential application for the extraction and preconcentration of hydrophilic analytes from complex fatty samples. [Copyright &y& Elsevier]

Abstract: In this work, we proposed a simple co-mixing method to fabricate magnetic one-dimensional polyaniline (denoted as 1D-PANIs/MNPs). One-dimensional polyanilines (1D-PANIs) and magnetic nanoparticles (MNPs) were prepared by chemical oxidation and solvothermal methods, respectively. When MNPs and 1D-PANIs (with mass ratio 4:1) were co-mixed and vortexed evenly in a solvent (e.g., ethanol, water, acetonitrile), they could assemble into 1D-PANIs/MNPs spontaneously and thus be magnetically separable. To testify the feasibility of 1D-PANIs/MNPs in sample preparation, it was applied as the sorbent for magnetic solid phase extraction (MSPE) of fluoroquinolones (FQs) in honey samples. Under optimized conditions, a rapid, convenient, and efficient method for the determination of four FQs in honey samples by 1D-PANIs/MNPs-based MSPE coupling with high performance liquid chromatography with fluorescence detection (HPLC-FLD) was established. The limits of detection (LODs) for four FQs ranged from 0.4 to 1.4ngg−1. The intra- and interday relative standard deviations (RSDs) were less than 17.6%. The recoveries of FQs for three spiked honey samples ranged from 86.3 to 121.3%, with RSDs of less than 16.3%. [Copyright &y& Elsevier]