Development of a Liquid Chromatography Tandem Mass Spectrometric Method for Simultaneous Determination of 15 Aminoglycoside Residues in Porcine Tissues

A quantitative and confirmatory method has been developed for simultaneous determination of 15 aminoglycoside (AG) residues in porcine tissues (muscle, liver and kidney) by liquid chromatography tandem mass spectrometry (LC-MS/MS). The analytes were extracted from different matrices with aqueous trichloroacetic acid solution (5 %, w/v) followed by solid phase extraction (SPE) clean-up under optimised conditions. Due to the different pK a values of the compounds, two consecutive SPE steps using Oasis HLB cartridges were used to purify all 15 AGs from sample extracts, with 9 AGs quantitatively retained on Oasis HLB cartridges at pH <1 and the other 6 AGs retained at pH 8.5. The analytes were separated on a reversed-phase C18 column and eluted with water and acetonitrile containing the ion-pair reagent heptafluorobutyric acid (HFBA). The LC-MS/MS method was validated according to Decision 2002/657/EC. The optimised procedure was successfully applied to analyse 100 real porcine tissue samples (60 muscles, 20 livers and 20 kidneys) collected from local markets in southern China, demonstrating that the method is robust and useful for determination of residues of the 15 target AGs in porcine tissue samples.