Direct analysis of nitrocatechol-type glucuronides in urine by capillary electrophoresis-electro spray ionisation mass spectrometry and tandem mass spectrometry

Direct, quantitative capillary electrophoresis-electrospray ionisation mass spectrometric (CE-ESI-MS) and tandem mass spectrometric (CE-ESI-MS-MS) met hods are described for the quantitation of 3-O-glucuronides of E- and Z-ent acapone isomers (EEG and EZG) and tolcapone (TG) in urine. 3-O-Glucuronide of nitecapone was used as internal standard. Good separation of glucuronide s was achieved with 20 mM ammonium acetate as separation solution at pH 6.8 4. Stacking was used to increase the sensitivity of the method by introduci ng samples in 5 mM ammonium acetate. CE-ESI-MS and CE-ESI-MS-MS methods are linear with correlation coefficients better than 0.9983 and 0.9982, and re peatable with relative standard deviations below 9 and 14%, respectively Th e limit of detection (LOD) in CE-ESI-MS at signal-to-noise ratio 3 is 100 n g/ml for EEG and EZG and 250 ng/ml for TG. The CE-ESI-MS-MS method was the more sensitive; LOD was 7 ng/ml for all compounds, without any concentratio n of the sample. (C) 2000 Elsevier Science B.V. All rights reserved.