ANALYSIS OF CATECHOL-TYPE GLUCURONIDES IN URINE SAMPLES BY LIQUID-CHROMATOGRAPHY ELECTROSPRAY-IONIZATION TANDEM MASS-SPECTROMETRY

A direct and fast liquid chromatographic-electrospray ionization-tande m mass spectrometric (LC-ESI-MS-MS) method is described for the determ ination of 3-O-glucuronides of E- and Z-entacapone, nitecapone and tol capone and 1-O- and 2-O-glucuronides of 4-nitrocatechol in urine. p-Ni trophenyl beta-D-glucuronide was used as internal standard. Spiked uri ne samples were prepared by solid-phase extraction and analysed by iso cratic LC-ESI-MS-MS in negative ion mode. The ESI mass spectra showed an abundant deprotonated molecule [M-H](-), which was chosen as precur sor ion. Collisionally induced dissociation of [M-H](-) in MS-MS resul ted in the loss of neutral glucuronide moiety and in the appearance of an intense negatively charged drug molecule, which was chosen as the product ion to be monitored in the LC-MS-MS analysis. The new method s howed good linearity (r(2)>0.997) and repeatability of the method (rel ative standard deviation <2.56%). The limits of detection were determi ned to be 0.1-0.2 mu g/ml when 5 mu l of the spiked urine was used for the analysis (5-10 pg of glucuronide introduced to ESI-MS-MS). (C) 19 98 Elsevier Science B.V.