Rapid determination of diuretics in human urine by gas chromatography-mass spectrometry following microwave assisted derivatization

This work presents a complete method for the screening and confirmation analysis of diuretics in human urine by gas chromatography-mass spectrometry (GC-MS). The method comprises a pretreatment stage (extraction, preconcentration and derivatization to form the corresponding methyl derivatives) and the subsequent analysis of the derivatized extracts by GC-MS. Particularly, the derivatization stage, necessary to form the methyl derivatives of the compounds detectable by the GC-MS technique, is carried out under microwave irradiation rather than with direct thermal heating, thus reducing the incubation time from 3 h to 10 min. Microwave assisted derivatization also allowed an improvement of the limits of detection (LODs) for all the compounds here considered. The technique is particularly suitable for the rapid analysis of huge population of samples, as it is the case of urine analysis by the antidoping laboratories, and especially in all those occasions where rapid response times are requested. (C) 2002 Elsevier Science B.V. All rights reserved.