Simultaneous determination of malachite green, crystal violet and their leuco-metabolites in aquaculture water samples using monolithic fiber-based solid-phase microextraction coupled with high performance liquid chromatography

Abstract

In this work, a convenient, sensitive and environmentally friendly method for simultaneous monitoring of malachite green (MG), crystal violet (CV), leucomalachite green (LMG) and leucocrystal violet (LCV) in aquaculture water samples was developed by coupling monolithic fiber-based solid-phase microextraction (MF/SPME) to high performance liquid chromatography with visible and fluorescence detection. The MF/SPME based on dual functional monomers was used to concentrate target analytes. Because there were multiple interactions between the sorbent and analytes, MF/SPME exhibited a high extractive capability toward analytes. In the optimized process, several key parameters including desorption solvent, pH value and ionic strength in the sample matrix, and extraction and desorption times were investigated. Under the optimized extraction conditions, the limits of detection (S/N = 3) and limits of quantification (S/N = 10) of the developed method were 0.013–0.30 μg L⁻¹ and 0.043–0.99 μg L⁻¹, respectively. Satisfactory linearity was achieved for analytes with the correlation coefficients (R²) above 0.99. Acceptable method reproducibility was achieved by evaluating the repeatability, intermediate precision, and fiber-to-fiber and batch-to-batch reproducibility with relative standard deviations (RSDs) of all less than 11%. Finally, the proposed method was successfully applied to the determination of MG, CV, LMG and LCV in several aquaculture water samples. Recoveries obtained for the determination of the target analytes in spiked samples ranged from 81.0% to 111%, with RSD below 11% in all cases.