Headspace solid-phase microextraction procedure for gas-chromatography analysis of toluene in urine

Toluene is widely used in industrial and laboratory applications and in many countries is related with social problems of abuse. Unaltered urinary toluene was introduced as a bioindicator of occupational exposure to the solvent, but its analysis presents difficulties due to the low levels of the compound excreted in urine. A gas-chromatography/flame ionization method for toluene in urine is described using headspace solid-phase microextraction and establishing the better conditions for two different extracting phases: polydimethylsiloxane (PDMS) and carboxen-PDMS. The carboxen-PDMS fiber showed lower quantifying limit (12.5 ng mL(-1)), better extraction efficiency (up to 28.1%) and repeatability (CV < 4.9%) than PDMS coating. The method was applied to analysis of toluene in urine of workers from car repair shops exposed to low solvent levels.