Development of a PRiME Cleanup Procedure for the Purification of Avermectins in Grass Carps and Liquid Chromatography-Tandem Mass Spectrometry Analysis

Avermectins were illegally used and detected in aquaculture recently. In this study, a process, robustness, improvements, matrix effects, ease of use (PRiME) pass-through solid-phase extraction (SPE) was developed for the purification of avermectins in grass carp (Ctenopharyngodon idella) tissue. The eluate was directly analyzed by ultra-performance liquid chromatography (UPLC) and tandem mass spectrometry (MS/MS). The conditions were optimized by using 90% methanol (0.1% formic acid) as extracting solvent with volume of 3 mL. The MS/MS parameters were also tested for selecting the optimum precursor ions, such as [M+H](+) and [M+NH4](+). Afterwards, this methodology was validated in terms of linearity (0.9989-0.9997), limit of detection (LOD <= 1.10 mu g kg(-1)), precision (RSD 1.88-4.85%), recovery (76.3-90.7%), etc., indicating its efficiency and robustness. Finally, five batches of grass carps (n = 6) from local markets were analyzed, and the results indicated the presence of abamectin in two fish samples originating from illegal use or cross contamination of drug. The PRiME technique can simplify the sample preparation procedure by avoiding the tedious steps, such as conditioning and washing. The successful application of the PRiME SPE and UPLC-MS/MS method indicated its superiority in detecting low levels of avermectins from the violation of regulation.