Determination Of Macrolides Residues In Animal Food Products By LC-ESI-MS/MS

In this paper the new liquid chromatography-electrospray tandem mass spectrumetry method was developed for the determination of eight commolonly used macrolides in pork tissues, egg, and milk. Stable isotope compound ¹³C6-erythromycin was used as internal standard. Multi-reaction monitoring (MRM) was employed for quantitative analysis. The LC separation was performed on a Cg analytical column(150 mm ×2.1 mm i.d.) with a gradient system of 0.1% formic acid water -methanol (containing 0.15‰ acetic acid) as the mobile phase at the flow rate of 0.2 mL/min. Satisfactory linearity, 0.5-100 ng/mL, of each compound was obtained in the method.A liquid-liquid extraction and Oasis HLB clean-up procedure was developed for pork tissues Recoveries were ranged from 64.2% to 111.4% for all compounds at three different spiked levels and the limit of detections (LODs) ranged from 0.012 to 0.195 μg/kg, with relative standard deviations (R.S.D.s) between 2.9% and 18.6%.Simultaneous determination of the eight macrolides in egg and milk using matrix solid-phase dispersion (MSPD) coupled with SPE is presented. Recoveries for the LC-ESI-MS/MS procedure ranged from 63.0% to 111.0% in egg and milk, and the LODs ranged from 0.010to 0.172 μg/kg, with R.S.D.s between 3.0% and 18.1%.Simultaneous determination of macrolides multiresidue haven't been reported in china, and matrix solid-phase dispersion (MSPD) coupled with SPE in eggs and milk haven't been reported in world. The sensitivity and reproducibility of these new methods were excellent. The results demonstrated that these methods are simple, accurate and suitable for a qualitative and quantitative analysis of these macrolides in animal products.Using the improved LC-ESI-MS/MS established in this work, the eight macrolides residues of the animal products from local markets were determined. Samples positive were 35% of samples detective, but all below the maximum...