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 residue in bovine kidney, liver, muscle and fat have been developed. The determinative method is a single-column HPLC ion-exchange procedure that incorporates a two-step post-column oxidation of the secondary amines to primary amines followed by derivatization with o-phthalaldehyde. 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 spectinomycin. The recovery of spectinomycin from all tissues was >80% and the variability (R.S.D.) was generally <10%. For liver, an alternative reversed-phase HPLC separation was required for incurred-residue samples. The confirmatory method employed an atmospheric pressure chemical ionization-MS-MS approach utilizing a rapid reversed-phase HPLC system with a mobile phase of methanol and 1% acetic acid. The protonated molecular ion for spectinomycin at m/z 333 produced four diagnostic reaction-product ions at 98, 116, 158 and 189 for confirmation. The method was validated to a lower limit of confirmation of 0.10 mu g/g. (C) 1998 Published by Elsevier Science B.V. All rights reserved.