Determination of multi-residue for malachite green, gentian violet and their metabolites in aquatic products by high-performance liquid chromatography coupled with molecularly imprinted solid-phase extraction

A sorbent was synthesized and investigated for molecularly imprinted solid-phase extraction (MISPE). Molecularly imprinted polymers (MIPs) were synthesized via precipitation polymerization procedure, where methacrylic acid (MAA) was used as functional monomer and ethylene glycol dimethacrylate (EDMA) as cross-linking agent. The imprinting effect and selectivity of the MISPE were evaluated by elution experiments. The resulting MISPE showed high extraction selectivity to malachite green, gentian violet and their metabolites, which may be caused by both the ion exchange and the hydrophobic interactions. The determination of multi-residue for malachite green, gentian violet and their metabolites in aquatic products by HPLC coupled with MISPE was also investigated. The mean recoveries calculated by solvent calibration curve for malachite green (MG), gentian violet (GV), leucomalachite green (LMG) and leucogentian violet (LGV) were from 89.8% to 99.1% for grass carp, 90.6% to 101.2% for shrimp and 91.3% to 96.3% for shellfish. The decision limit (CCα) and the detection capability (CCβ) obtained for MG, GV, LMG and LGV were in the range of 0.11–0.14 and 0.19–0.24 μg kg−1 for grass carp, shrimp and shellfish. The MISPE was successfully used off-line for the determination of MG, GV and their metabolites in aquatic products.