Simultaneous determination of seven penicillins in muscle, liver and kidney tissues from cattle and pigs by a multiresidue high-performance liquid chromatographic method

A high-performance liquid chromatographic (HPLC) method based on solid-phas e extraction (SPE) was developed for determination of amoxicillin, penicill in G (benzylpenicillin), ampicillin, oxacillin, cloxacillin, nafcillin and dicloxacillin in muscle, liver and kidney tissues of pigs and cattle. The c ompounds were extracted in aqueous solution by precipitation of organic mat erials with a mixture of sulphuric acid and sodium tungstate. The extract w as cleaned up by SPE on a divinylbenzene-co-N-vinylpyrrolidone polymeric so rbent. Further clean-up was performed by liquid-liquid partition with dieth yl ether. The extract was derivatised with benzoic anhydride and 1,2,4-tria zole mercury (LT) reagent. Chromatography was performed by reversed-phase g radient HPLC on a C-18 column with ultraviolet detection at 323 nm. The lim its of detection estimated by a conservative model were in the range 8.9-11 .1 mu g/kg for amoxicillin, penicillin G, ampicillin, oxacillin, cloxacilli n and nafcillin and 18.3-20.9 mu g/kg for dicloxacillin. The mean recovery range was 66-77% for amoxicillin, 73-75% for penicillin G, 81-82% for ampic illin, 73-76% for oxacillin, 74-75% for cloxacillin, 66-72% for nafcillin a nd 58-65% for dicloxacillin. (C) 1999 Elsevier Science B.V. All rights rese rved.