Simultaneous determination of six quinolones in pig muscle by liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry.

An LC-MS method is described for the confirmation of six quinolones (enrofloxacine, ciprofloxacine, marbofloxacine, danofloxacine, sarafloxacine and difloxacine) in pig muscle. The quinolones were extracted from muscle (2 g) with phosphate buffer (pH 7.4). After centrifugation, the extract was purified on a C18 solid-phase extraction cartridge. Samples were analysed by LC with gradient elution on a C18 column and detected by MS via an atmospheric pressure chemical ionisation interface. For each compound, an intense pseudo-molecular ion [M+H]+ is obtained. The assay is specific and reproducible and allows the confirmation of the six quinolones at the 7.5 micrograms kg-1 level in pig muscle.