QUANTITATION OF SPECTINOMYCIN RESIDUES IN BOVINE-TISSUES BY ION-EXCHANGE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH POSTCOLUMN DERIVATIZATION AND CONFIRMATION BY REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY ATMOSPHERIC-PRESSURE CHEMICAL-IONIZATION TANDEM MASS-SPECTROMETRY

Determinative and confirmatory methods of analysis for spectinomycin r esidue in bovine kidney, liver, muscle and fat have been developed. Th e determinative method is a single-column HPLC ion-exchange procedure that incorporates a two-step post-column oxidation of the secondary am ines to primary amines followed by derivatization with o-phthalaldehyd e. The method was validated in all tissues to a low-end concentration of 0.10 mu g/g (limit of quantitation) and to a high-end of 10 mu g/g for kidney, which is the rate-limiting tissue for residues of spectino mycin. The recovery of spectinomycin from all tissues was >80% and the variability (R.S.D.) was generally <10%. For liver, an alternative re versed-phase HPLC separation was required for incurred-residue samples . The confirmatory method employed an atmospheric pressure chemical io nization-MS-MS approach utilizing a rapid reversed-phase HPLC system w ith a mobile phase of methanol and 1% acetic acid. The protonated mole cular ion for spectinomycin at m/z 333 produced four diagnostic reacti on-product ions at 98, 116, 158 and 189 for confirmation. The method w as validated to a lower limit of confirmation of 0.10 mu g/g. (C) 1998 Published by Elsevier Science B.V. All rights reserved.