Identification and determination of antibiotics from various classes in food- and feedstuffs by matrix-or surface-assisted laser desorption/ionization mass spectrometry

Methods are proposed for the identification and determination of residual quantities of antibiotics from various classes in food- and feedstuffs for animals by matrix-or surface-assisted laser desorption/ionization mass spectrometry (MALDI/SALDI MS). It is shown that acetonitrile is efficient for the extraction of antibiotics without additional extract purification. The limits of detection for antibiotics in the indicated products are 0.01-0.3 mu g/kg in MALDI MS and 0.001-0.03 mu g/kg in SALDI MS at the signal-to-noise ratio 4. The relative standard deviation of the results of determination of antibiotics does not exceed 10% in feedstuffs and premixes at the analytical range 20-400 mg/kg for monensin and narasin, 0.2-200 mg/kg for tilmicosin, and 20-1000 mg/kg for avilamycin and a weighed portion of feedstuff 1.0 g. The time of analysis is 40-50 min.