Analysis of colistin A and B in fishery products by ultra performance liquid chromatography with positive electrospray ionization tandem mass spectrometry

Abstract

A rapid and simple method for the determination of colistin A and B in fishery products by reversed phase ultra performance liquid chromatography with positive electrospray ionization tandem spectrometry (UPLC–ESI-MS/MS) method was described. The samples were extracted with 1.0mol/L of hydrochloric acid in methanol–water and then purified on the PLS solid phase extraction columns. Then the eluate was evaporated to less than 1mL under a gentle stream of nitrogen at 40°C and formic acid–acetonitrile–water (0.2/10/90, v/v/v) was added to adjust volume to 1mL final volume. An aliquot (10μL) was injected onto the LC column for analysis with the mobile phase of 0.2% formic acid in acetonitrile and 0.2% formic acid in water at 0.20mLmin−1. Multiple reaction monitoring was performed using precursor-product ion combinations. Calibration curves were linear from 200ng/mL to 2000ng/mL for colistin A and B. Mean recoveries were between 72.9% and 82.9%. The LOD was 10.0μg/kg and LOQ was 40.0μg/kg. The intra-day assay precision values for QC samples were between 2.17% and 9.00%, and inter-day values were between 2.80% and 6.97%. The method has merits of simplicity, sensitivity and rapidity, and it can be used for the determination of colistin A and B in fishery products.