Determination of thiazolidine-4-carboxylates in urine by chloroformate derivatization and gas chromatography-electron impact mass spectrometry

✍ Scribed by Ho-Sang Shin; Hye-Sil Ahn; Byung-Hoon Lee

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 205 KB
• Volume: 42
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/jms.1255

✦ Synopsis

Abstract

The derivatization method of thiazolidine‐4‐carboxylic acid (TZCA) and methyl‐thiazolidine‐4‐carboxylic acid (Me‐TZCA) in urine with alcohol/chloroformate was achieved. TZCA and Me‐TZCA were derivatized in one step in urine with ethyl chloroformate in 1 min at room temperature. The derivatives of TZCA and Me‐TZCA had very good chromatographic properties and offered very sensitive response for gas chromatography‐electron impact ionization‐mass spectrometry (GC‐EI‐MS). On the basis of derivatization, the method for simultaneous determination of TZCA and Me‐TZCA in human urine was developed. Deuterated Me‐TZCA (Me‐TZCA‐d~4~) was synthesized as the internal standard (IS) for the analysis of urine samples. TZCA and Me‐TZCA were derivatized and extracted from urine at pH 9.5 with toluene, and then the dried extract was dissolved with 100 µl ethyl acetate and injected in GC/MS system. The recoveries of TZCA and Me‐TZCA were about 102 and 103%, respectively, at the concentration of 0.05 mg/l. The method detection limits (MDL) were 1.0 and 0.5 µg/l, respectively, for TZCA and Me‐TZCA in 1 ml human urine. The coefficients of variation of TZCA and Me‐TZCA were less than 6% at the concentrations of 0.05 and 0.2 mg/l, respectively. To assess the formation of TZCA during inhalation with formaldehyde (FA) (about 3.1 and 38.1 ppm FA in air), urine samples from rats were taken during 3 days after initiation of treatment. The mean amount of TZCA determined was 0.07 mg/l in control group and 0.18 mg/l during treatment with 3.1 ppm. The TZCA levels increased up to about 1.01 mg/l during treatment with 38.1 ppm. It is planned to study whether urinary TZCA can be used as an indicator in the biological monitoring of exposure to FA. Copyright © 2007 John Wiley & Sons, Ltd.