title: Analytical method for urinary metabolites as biomarkers for monitoring exposure to phthalates by gas chromatography/mass spectrometry.
abstract: Phthalates, widely used as plasticizers, have been detected in indoor air, but there have been few reports on methods of analyzing urinary metabolites as biomarkers to monitor exposure to di-n-pentyl phthalate or di-n-hexyl phthalate. Presented here is a cost-effective and sensitive analytical method for the determination of urinary metabolites of phthalates containing these two compounds. Nine urinary phthalate metabolites were enzymatically hydrolyzed and extracted with toluene: monomethyl phthalate, monoethyl phthalate, monoisobutyl phthalate, mono-n-butyl phthalate, mono-n-pentyl phthalate, mono-n-hexyl phthalate, monocyclohexyl phthalate, monobenzyl phthalate and mono(2-ethyl-5-carboxypentyl) phthalate. After transformation to their tert-butyldimethylsilyl derivatives, they were analyzed by gas chromatography/mass spectrometry in the electron impact ionization mode. The calibration curves for the metabolites were linear at urinary concentrations of up to 30 μg/L, showing that they could be determined accurately and precisely (detection limits 0.1-0.4 μg/L, quantification limits 0.3-1.3 μg/L). The urine samples collected could be stored for up to 1 month at -20°C. The proposed analytical method was used to examine urine samples from seven healthy volunteers. This method should be useful for monitoring phthalate exposure in the general population.
authors.affiliation: Osaka Prefectural Institute of Public Health, Osaka, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Yoshida
mesh_terms: D015415:Biomarkers / Q000652:urine*; D002138:Calibration; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D057230:Limit of Detection; D016273:Occupational Exposure; D010795:Phthalic Acids / Q000652:urine*; D015203:Reproducibility of Results
chemical_list: D015415:Biomarkers; D010795:Phthalic Acids
keywords: general population; plasticizer; tert-butyldimethylsilyl derivative; urine