Determination of urinary ortho- and meta-cresol in humans by headspace SPME gas chromatography/mass spectrometry

ortho-Cresol (o-C) and meta-cresol (m-C) are minor urinary metabolites of toluene, a widely used chemical with neurotoxicological properties. A new assay for their determination in human urine is here proposed. Urinary cresol sulphates and glucuronates are submitted to acid hydrolysis, urine is neutralized, added with o-cresols-d(8), and analytes are sampled in the headspace of urine by SPME using a polydimethylsiloxane fiber. Analysis is performed by GC/MS using, for separation, either a SupelcoWax10 (for o-C) or a chiral CP Cresol (for o-C and m-C) column. The method is very specific, with a range of linearity 0-5.0 mg/l, within- and between-run precision, as coefficient of variation, <15% and <19%, limit of detection of 0.006 mg/l for o-C and 0.007 mg/l for m-C. The procedure is applied to the quantification of cresols in urine from workers exposed to toluene and from subjects belonging to the general population. (C) 2005 Elsevier B.V. All rights reserved.