Determination of low concentrations of benzene in urine using multi-dimensional gas chromatography

Abstract

A method for the determination of benzene in urine of occupationally or environmentally exposed persons was developed. The method was based on dynamic headspace, preconcentration on a solid sorbent, followed by thermal desorption and gas chromatographic determination. To achieve sufficient selectivity, we used multi-dimensional gas chromatography in combination with the inexpensive and robust flame ionisation detector. The limit of detection was 7 ng l⁻¹ and the limit of quantification was 23 ng l⁻¹. The linearity was good (correlation coefficient 0.999) in the range examined (20–4000 ng l⁻¹) and the repeatability was 9%. The average recovery at low concentrations (20–400 ng l⁻¹) was 86%. Analysis of a certified reference material of benzene in water, traceable to NIST, did not differ significantly from the certified value. Samples, frozen (−20 °C) in glass bottles sealed with Teflon–silicon septa, were stable for 1 year and refrigerated samples (4 °C) for at least 1 week. Loss of benzene during the collection and transfer of urine was investigated and found to be acceptable. The method is a cost effective and robust alternative to GC-MS and permits reliable quantification of occupational exposure and, in most cases, also of urine concentrations that can be expected from environmental exposure.