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Measurement of chiral thiol compounds such as glutathione (GSH), cysteine (Cys), and homocysteine (Hcy) in human serum plays an important role in the early diagnosis and warning of cardiovascular disease, neurodegenerative disease, and cancer. We developed a novel chiral mass spectrometry derivatization reagent, (R)-(5-(3-isothiocyanatopyrrolidin-1-yl)-5-oxopentyl) triphenylphosphonium (NCS-OTPP), with triphenylphosphine (TPP) as a basic structure carrying a permanent positive charge for the diastereomeric separation of chiral thiol compounds by ultrahigh-performance liquid chromatography coupled to quadrupole-Orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS). A novel method was developed for simultaneous determination of three kinds of chiral thiol compounds based on the NCS-OTPP derivatization method. Three kinds of chiral thiol compounds on a YMC Triart C18 (2.0 × 150 mm, 1.9 μm) column with Rs were 1.56-1.68. The protonated precursor to product ion transitions monitored for GSH was m/z 780.16→747.24/473.18, Cys was m/z 594.20→561.18/473.18, and Hcy was m/z 608.21→575.19/473.18. An excellent linearity for all the analytes with correlation coefficients ≥ 0.9995 and suitable precision with inter-day and intra-day coefficients of variation RSDs was 0.83-4.06% and 0.95-3.11%. Satisfactory accuracy with recoveries between 83.73 and 103.35% was observed. The limit of detection (S/N = 3) was 2.4-7.2 fmol. Furthermore, the method was successfully applied to the simultaneous determination of three kinds of free and total thiol compounds in serum from 10 healthy volunteers at normal and stress states., Competing Interests: Declaration of Competing Interest The authors declare that there are no conflicts of interest., (Copyright © 2021 Elsevier B.V. All rights reserved.)

A novel UHPLC–MS/MS method with high sensitivity and selectivity for simultaneous detection and chiral resolution of DL-amino acids in beer was established using the newly developed mass spectrometry probe (S)-(3-(4-carboxythiazolidin-3-yl)-3-oxopropyl) diphenylsulfonium (CTOD). The gradient analysis of five chiral amino acids (DL-Asp, DL-Glu, DL-Ala, DL-Pro, and DL-Phe) was carried out on a BEH C18 (2.1 × 150 mm, 1.7 μm) for 30 min with a mobile phase of 0.1% formic acid aqueous solution and 0.1% formic acid methanol/acetonitrile (7:3) solution. The resolutions of DL-amino acids ranged from 1.71 to 5.42. The correlation coefficients were ≥ 0.9994 in the range of 0.25 to 1200 pmol. Meanwhile, limits of detection (LOD) and limits of quantitative (LOQ) analysis were 0.05–0.25 pmol and 0.13–0.50 pmol, respectively. Furthermore, the intra-day and inter-day precision ranged from 0.34% to 6.31%, and the average recoveries ranged from 97.50% to 107.50%. The method was applied to the quantitative analysis and comparison of DL-amino acids in beer samples from 10 different manufacturers, and it was found that the beers were rich in D-amino acids. Four D-AAs including D-Ala, D-Pro, D-Glu, D-Phe (1.9–29.8 μmol L−1) and five L-AAs including L-Pro, L-Ala, L-Phe, L-Glu, L-Asp (5.3–2315.9 μmol L−1) were detected in the beer samples. The average content of L-AAs in the 10 beer samples was significantly higher than that of D-AAs. This study provides a new method for detecting chiral amino acids in beer and reliable data for evaluating the nutritional value of beer. Highlights: We developed a new UHPLC-MS/MS method with high sensitivity and selectivity for the quantification of five DL-amino acids in beer. The analysis of five DL-amino acids in beer by LC-MS is the first report. The method can be used to determine the content of DL-amino acid in beer from different manufacturers. [ABSTRACT FROM AUTHOR]

• A highly sensitive UHPLC-HRMS method was provided for the simultaneous analysis of GSH, DL-Cys and DL-Hcy. • D-Hcy was determined in human urine for the first time. • Fitted curves for ratios of D/L-Cys and D/L-Hcy were a convenient and effective method to evaluate oxidative stress. A high-sensitivity and -selectivity mass spectrometry derivatization reagent, (R)-(5-(3-isothiocyanatopyrrolidin-1-yl)-5-oxopentyl) triphenylphosphonium (NCS-OTPP), was developed for the enantiomeric separation of chiral thiol compounds as prospectively important diagnostic markers for oxidative stress-related diseases. Complete separation of GSH, DL-Cys, and DL-Hcy was achieved. The parent ions of all derivatives had a fragment of m/z 473.18 and a structure of m/z 75.95 (R-S = C-S-R'), conducive to qualitative and quantitative analysis. Good linear relationships were obtained for all analytes (R2 ≥ 0.9995). The intra-day and inter-day precision were 0.82–5.16 % and 1.02–4.18 % in saliva, and 0.81–3.45 % and 0.99–6.47 % in urine, with mean recoveries of 83.31–105.66 % and 84.09–101.11 %, respectively. The limit of detection (S/N = 3) was 19.20–57.60 nM. Free and total GSH, DL-Cys, and DL-Hcy were detected simultaneously in saliva and urine from 10 volunteers in the normal, stressed, and stable states by UHPLC-Q-Orbitrap HRMS. The thiol compounds were quantitatively related to oxidative stress state changes. [ABSTRACT FROM AUTHOR]