Multi-residue quantitation of aminoglycoside antibiotics in kidney and meat by liquid chromatography with tandem mass spectrometry

Quantitative methods using liquid chromatography coupled with tandem mass spectrometry were developed for seven kinds of aminoglycoside antibiotics in kidney and muscle tissues. Mass spectral acquisition was performed in the positive-ion mode by applying multiple reaction monitoring. Liquid chromatographic separation employed a ZIC-HILIC column (SeQuant) for hydrophilic interaction chromatography. Extraction of the aminoglycosides was performed using liquid extraction with a phosphate buffer containing trichloroacetic acid, followed by a solid-phase clean-up procedure on a weak cation-exchange column with carboxypropyl (CBX) SPE cartridge (Mallinckrodt Baker). The limits of quantification were 25 ng g-1 for gentamicin, 50 ng g-1 for spectinomycin, dihydrostreptomycin, kanamycin and apramycin, and 100 ng g-1 for streptomycin and neomycin. These are well below the maximum residue limits set by the Codex Alimentarius Commission. The recoveries of all compounds from all tissues fortified at the level of quantification limits of 500 and 1000 ng g-1 were 70%, and the variability (relative standard deviation) was generally 12%.