Abstract: Multi-residue analysis method for penicillins was
developed and validated in bovine muscle, chicken, milk, and flatfish.
Detection was based on liquid chromatography tandem mass
spectrometry (LC/MS/MS). The developed method was validated for
specificity, precision, recovery, and linearity. The analytes were
extracted with 80% acetonitrile and clean-up by a single
reversed-phase solid-phase extraction step. Six penicillins presented
recoveries higher than 76% with the exception of Amoxicillin
(59.7%). Relative standard deviations (RSDs) were not more than
10%. LOQs values ranged from 0.1 and to 4.5 ug/kg. The method was
applied to 128 real samples. Benzylpenicillin was detected in 15
samples and Cloxacillin was detected in 7 samples. Oxacillin was
detected in 2 samples. But the detected levels were under the MRL
levels for penicillins in samples.