Determination of 1-pyrenol in urine by gas chromatography with mass selective detector

Abstract

Urinary 1-pyrenol belongs to the biological markers of exposure to the polyaromatic hydrocarbons. Several methods for the determination of 1-pyrenol in urine necessarily include enzymatic hydrolysis, extraction from the biological sample, and derivatization with the silylating agent. Enzymatic hydrolysis and silylation take very long time: 16 hours and 40 minutes respectively. A shorter and more sensitive version of the determination of 1-pyrenol in urine by gas chromatography with mass-selective detection is proposed. Enzymatic hydrolysis with β-glucuronidase is used for 1h to digest the conjugated form of 1-pyrenol (as glucuronide). After the enzymatic hydrolysis, the analyte is extracted from the biological matrix by hexane extraction, followed by evaporation of the extract to dry residue in an inert gas stream. The optimum conditions for liquid extraction are established by varying the ratio of salting out agent : extraction time : extraction ratio. The dry residue is re-dissolved and derivatized in the silylating reagent N, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA) into trimethylsilyl ether at room temperature for 5 minutes. The analysis of the trimethylsilyl extract is carried out by gas chromatography on HP-5MS capillary column with mass-selective detection. The analyte is identified by the retention time and the ratio of the main and confirming ions. The high-accuracy determination is ensured by using the internal standard 1-pyrenol-d 9 . The range of detectable concentrations of the method is from 0.1 to 100 μg/l. Repeatability and interlaboratory precision are 4.4% and 6.4% respectively. The systematic error turns out to be insignificant. The accuracy is 14%. The method is tested on the urine samples of workers with the main professions in the aluminum production industry.