Analysis of urinary biomarkers for exposure to alkyl benzenes by isotope dilution gas chromatography-mass spectrometry

Abstract

A validated GC-MS method for the analysis of urinary metabolites of alkyl benzenes is reported. Metabolites for exposure to toluene, xylene and ethylbenzene were analyzed simultaneously using stable isotope substituted internal standards. The method entailed acidic deconjugation of urine samples followed by extractive alkylation with pentafluorobenzyl bromide as alkylating agent. The resulting pentafluorobenzyl derivatives of ortho-, meta-, para-cresol, mandelic acid (MA), hippuric acid (HA) and ortho-, meta-, para-methylhippuric acid (MHA) were then quantified by SIM. Optimized reaction conditions for the extractive alkylation step are reported. The derivatives were found to be sufficiently stable for overnight batch analysis. The LODs were below 0.1 micromol/L for the cresols and below 1 micromol/L for MA and the HAs. Within-batch precision for o-MHA was 7%, for m-MHA 5%, for p-MHA 5.2% and below 5% for the rest of the analytes.

Direct methyl esterification with 2,2-dimethoxypropane for the simultaneous determination of urinary metabolites of toluene, xylene, styrene, and ethylbenzene by gas chromatography-mass spectrometry

“…We developed and validated a simple and accurate GC‐MS method for the simultaneous determination of toluene, xylene, styrene, and ethylbenzene urinary metabolites. Several simultaneous GC‐MS methods have been reported . In these methods, several derivatization procedures such as alkylation, methyl esterification, silylation, and alkoxycarbonylation were used to enable GC analyses because these metabolites have low volatility.…”

“…For accurate and comprehensive evaluation of combined exposure, simultaneous determination of these urinary metabolites is desired for routine biological monitoring. Several simultaneous determination methods for these urinary metabolites have been reported, including gas chromatography‐mass spectrometry (GC‐MS), high‐performance capillary electrophoresis (HPCE), high‐performance liquid chromatography‐ultraviolet (HPLC‐UV) detection, high‐performance liquid chromatography‐hybrid quadrupole time‐of‐flight mass spectrometry (HPLC‐QqTOF‐MS), and ultra‐high‐performance liquid chromatography‐electrospray ionization tandem mass spectrometry (UPLC‐ESI‐MS/MS) . However, each of these methods has disadvantages.…”

Studies on styrene concentration in drinking water and hot beverages in some settings

“…Modern high-performance liquid chromatography (HPLC) with UV detection (Bourque et al, 1994;Fujii et al, 1999;Inoue et al, 1991), gas chromatography (GC) with flame ionization detection (Chakroum et al, 2008;Kataoka et al, 1991), and high-performance chromatography with mass spectrometry (Pacenti et al, 2008;Marais and Laurens, 2005) were performed for evaluating styrene. The level of styrene present in food and drinks depend on many factors such as heat, pH, fats, and the time of storage.…”

Magnetic graphene oxide as adsorbent for the determination of polycyclic aromatic hydrocarbon metabolites in human urine

“…Polycyclic aromatic hydrocarbons (PAHs) are a common carcinogen in mammals, which are mainly from incomplete combustion of organic matrices. Exposure to these environmental contaminants and their potential damage to public health has become a worldwide concern . Once PAHs in the polluted air are absorbed into human body, they can be converted to epoxide intermediates, such as diol‐epoxide, which is a highly reactive metabolite endangering cellular DNA .…”