MULTI-RESIDUE CONFIRMATION OF AMINOGLYCOSIDE ANTIBIOTICS AND BOVINE KIDNEY BY ION-SPRAY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY TANDEM MASS-SPECTROMETRY

An ion spray high-performance liquid chromatographic/tandem mass spect rometric (HPLC/MS/MS) method capable of determining the following six aminoglycosides in bovine kidney is presented: spectinomycin, hygromyc in B, streptomycin, dihydrostreptomycin, gentamicin C complex and neom ycin B. Tobramycin was used as an internal standard. This method uses an improved matrix solid-phase dispersion (MSPD) method for tissue ext raction. A gradient HPLC separation was developed with mobile phases c onsisting of aqueous 20 mM pentafluoropropionic acid and acetonitrile. Protonated molecules served as precursor ions for collision-induced d issociation (CID) and three product ions were chosen for each analyte for selected reaction monitoring (SRM) where possible. A validation st udy was conducted for the confirmation of dihydrostreptomycin, neomyci n B and four major components of the gentamicin C complex through SRM HPLC/MS/MS analysis of negative control, fortified and incurred bovine kidney samples. All of the samples analyzed could be confirmed with i on ratios within 15% of the daily mean of fortified standards and 90% of the samples had ion ratios within 10%. All compounds except spectin omycin could be detected (while monitoring three ions by SRM) in bovin e kidney tissue at or below the regulatory level of concern. MSPD reco veries were aceptable with the exception of the 27% value observed for spectinomycin.