Determination of volatile organic compounds in urine by solid phase microextraction

Volatile organic compounds (VOCs) are found at concentrations oof ppm in the industrial environment. To assess occupations and non-occupational exposures to these a valid method of biological monitoring that is easy to perform is needed. A new method has been developed to evaluate low concentrations of VOCs in urine samples by means of a Gore Tex(R)/Tenax diffusion sampling. The solvent is absorbed from the urine and concentrated in an absorbent substrate (Tenax) that is placed inside a Gore-Tex(R) membrane. Subsequently, the solvents are thermally desorbed from the Tenax and injected into a gas chromatography column (Thermal Tube Desorber-Supelco; 250 degrees C thermal flash; borosilicate capillary glass-column cross-linked dimethylsilicone 25 m length, 0.33 mm i.d., 0.02 mm film thickness; Gas Chromatograph-Mass Selective Detector). The method, which had not been previously employed for the determination of volatile organic substances in biological fluids, has a linear range which extends up to 50 mu g.l(-1) and gives results in excellent agreement with conventional head-space analysis, except in the region of low concentrations: the new method permits the quantitative determination of VOCs in quantities smaller than the detection limit of headspace analysis in conjunction with a mass spectrometer (approximately 1 mu g.l(-1)). The detection limit was estimated to be of 25 - 50 ng.l(-1) with a 36 mi urine sample.