SIMULTANEOUS DETERMINATION OF THIABENDAZOLE AND ITS MAJOR METABOLITE,5-HYDROXYTHIABENDAZOLE, IN BOVINE-TISSUES USING GRADIENT LIQUID-CHROMATOGRAPHY WITH THERMOSPRAY AND ATMOSPHERIC-PRESSURE CHEMICAL-IONIZATION MASS-SPECTROMETRY

A novel method is presented for the determination of thiabendazole and 5-hydroxythiabendazole in animal tissues. Samples are homogenised in buffer at pH = 7.0, extracted with ethyl acetate and cleaned up using CN solid-phase extraction columns. Thiabendazole and 5-hydroxythiabend azole are separated chromatographically using gradient elution and ana lysed by Liquid chromatography-mass spectrometry. Deuterated thiabenda zole is employed as an internal standard for thiabendazole determinati on; 5-hydroxythiabendazole is quantified via external standards. Sampl es are screened by monitoring the protonated molecular ions at m/z = 2 02 for thiabendazole, 206 for deuterated thiabendazole and 218 for 5-h ydroxythiabendazole using thermospray LC-MS. Positives are confirmed b y multiple ion monitoring using APCI LC-MS. Validation of the method w as carried out at 50, 100 and 200 mu g kg(-1). Recoveries for thiabend azole in bovine muscle, liver and kidney ranged from 96-103% with C.V. s between 0.7 and 4.8% and for 5-hydroxythiabendazole recoveries range d from 70-85% with C.V.s between 3.1 and 11.5%. (C) 1998 Elsevier Scie nce B.V. All rights reserved.