Determination of macrolides in feeds by capillary electrophoresis

A HPCE method has been developed for the separation of three macrolide antibiotics,Spiramycin(SPM),Tilmicosin(TIL) and Tylosin(TYL) in swine feeds.A systematic approach was used to maximise analyte differential electrophoretic mobility by manipulating electrolyte pH,composition and molarity.In addition,some instrumental parameters such as capillary length and diameter and applied voltage were varied.The analysis was performed in a 40 mmol/L Na2HPO4-20 mmol/L Citric acid buffer(pH 2.5) and an applied voltage of 25 kV was selected to effect the separation.The macrolides were completely resolved in less than 15 min in a 57 cm×75 μm I.D.fused-silica uncoated capillary.The linears of the three macrolides were 10-100 μg/g,and correlation coefficient of the three drugs was higher than 0.999 3.The LODs of SPM,TIL and TYL were 3.0,5.0 and 8.0 μg/g,respectively.The average recoveries were between 74.5% and 87.4%,and RSDs for intra-day and inter-day were lower than 8.1% and 7.0%,respectively.It is a fast,simple,economic and environmental friendliness method that allows the detection of positive feeds samples