Improved extraction of ethanol from human body fluids by headspace solid-phase microextraction with a carboxen-polydimethylsiloxane-coated fiber

Ethanol can be extracted from human whole blood and urine by headspace solid-phase microextraction (SPME) with a Carboxen-polydimenhylsiloxane-coated fiber. Whole-blood containing ethanol, with isobutanol as internal standard (IS), is heated at 60 °C in the presence of (NH4)2SO4 and sodium dithionite. A Carboxen-polydimethylsiloxane-coated SPME fiber is then exposed to the headspace in the vial for 15 min and then injected into a mdium-bore capillary GC injection port. For urine the SPME procedure is essentially the same as that for whole blood except that the sodium dithionite is omitted. Recoveries of ethanol and IS were, respectively, 1.98 and 28.1% for whole blood, and 2.91 and 35.1% for urine. The calibration curves for ethanol were linear in the range 2.5–400 mg L−1 for whole blood and 0.5–400 mg L−1 for urine; the detection limits for whole blood and urine were 0.5 mg L−1 and 0.2 mg L−1, respectively. Data obtained for determination of ethanol after the drinking of beer are presented for two subjects. This SPME method with the new fiber for ethanol and IS resulted in sensitivity 40–1080 times greater than that obtained with the previous SPME method employing a Carbowax-divinylbenzene-coated fiber.