LC/ESI-MS/MS Method for the Simultaneous Determination of Macrocyclic Lactone Parasiticides in Livestock Products and Fish

Abstract

An LC/ESI (positive-mode)-MS/MS method was developed for simultaneous quantification of 8 macrocyclic lactones (abamectin B1a, abamectin 8,9-Z isomer B1a, emamectin benzoate B1a, emamectin benzoate 8,9-Z isomer B1a, ivermectin, eprinomectin B1a, doramectin and moxidectin) in animal tissues, egg, milk and honey. The separation was achieved on a TSK-GEL ODS 100 V column (2.050 mm, 3 mm) with a mobile phase consisting of 0.1̮ formic acid in acetonitrile, and 0.1 mM ammonium formateῌ0.1̮ formic acid in water, at a flow rate of 0.2 mL/min with gradient elution. Linear calibration plots were obtained with high correlation coe$cients (r0.998ῌ0.999). The LOQ and LOD ranged from 0.02ῌ1.5 ng/mL and 0.1ῌ5 ng/mL, respectively. Average recoveries were in the range of 70.8ῌ117.1̮ with associated RSD values̮15̮ (n10) for repeatability and reproducibility. The spiking levels for recoveries and RSDs met the validation criteria for Japanese maximum residue limits (MRLs). Based on these results, the proposed analytical method has been proven to be highly e$cient and suitable for routine determinations of macrocyclic lactones in animal food matrices.