| Title: | Tandem derivatization combined with salting-out assisted liquid-liquid microextraction for determination of biothiols in urine by gas chromatography-mass spectrometry |
| Author(s): | Tsai CJ; Liao FY; Weng JR; Feng CH; |
| Address: | "Department of Fragrance and Cosmetic Science, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan. Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan. Department of Fragrance and Cosmetic Science, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan; Ph.D. Program in Toxicology, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan; Institute of Medical Science and Technology, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan; Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, 80708, Taiwan. Electronic address: chfeng@kmu.edu.tw" |
| DOI: | 10.1016/j.chroma.2017.09.069 |
| ISSN/ISBN: | 1873-3778 (Electronic) 0021-9673 (Linking) |
| Abstract: | "Detection of polar organic compounds (POCs) using gas chromatography (GC) is not straightforward due to high polarity, hydrophilicity, and low volatility of POCs. In this study, we report a tandem microwave-assisted derivatization method combined with salting-out assisted liquid-liquid microextraction (SALLME) to modify successively the polar groups of POCs in protic and aprotic solvents. Biothiols (cysteine and homocysteine) served as a proof of concept for this method because they possess three polar groups (thiol, amine, and carboxyl); the derivatizing reagent was 3,4,5-trifluorobenzyl bromide (Br-TFB) for alkylation. The solubility of the POCs in the protic or aprotic reaction medium affected the number of TFB molecules attached. Using the tandem derivatization with Br-TFB, the thiol and amine groups of biothiols were alkylated in the protic system, and the carboxylic groups of biothiols were alkylated in the aprotic system. The developed method was then successfully applied to measure biothiols in human urine. Because of the complex urine matrix and the lack of urine samples without endogenous biothiols, the standard addition method was utilized to avoid the matrix effect, check the recovery, and calculate the initial biothiol content in the urine. Regarding the linearity of the standard addition curves, the coefficient of determination was >0.996, and the linear regression showed satisfactory reproducibility with a relative standard deviation <3.9% for the slope and <8.8% for the intercept. The levels of cysteine and homocysteine in healthy human urine ranged from 28.8 to 111mumolL(-1) and from 1.28 to 3.73mumolL(-1), respectively. The proposed method effectively increased the sensitivity of GC-MS assays of water-soluble compounds in human urine" |
| Keywords: | Cysteine/urine *Gas Chromatography-Mass Spectrometry Humans Limit of Detection Linear Models *Liquid Phase Microextraction/instrumentation Microwaves Reproducibility of Results Solvents Sulfhydryl Compounds/*urine Urinalysis/*methods Cysteine Gas chromato; |
| Notes: | "MedlineTsai, Chia-Ju Liao, Fang-Yi Weng, Jing-Ru Feng, Chia-Hsien eng Netherlands 2017/10/11 J Chromatogr A. 2017 Nov 17; 1524:29-36. doi: 10.1016/j.chroma.2017.09.069. Epub 2017 Sep 29" |
