Selective enrichment and rapid determination of malachite green in aquaculture water using magnetic molecularly imprinted dispersive SPE coupled to SERS-PLS

Abstract

We report a rapid method for the selective enrichment and sensitive detection of malachite green (MG) in aquaculture water. Magnetic molecularly imprinted polymers (MMIPs) prepared via Pickering-emulsion polymerization were employed in a magnetic dispersive SPE workflow prior to surface-enhanced Raman spectroscopy (SERS). Partial least squares (PLS) models were built on preprocessed SERS spectra to predict MG concentrations. The optimised model achieved excellent linearity (R_train=0.9897; R_test=0.9836), a detection limit of 0.19 ng/mL, and spike recoveries of 80% to 110% in real aquaculture water. Results were benchmarked against HPLC, showing good agreement. The method integrates selective preconcentration with portable SERS readout, enabling on-site MG screening with high sensitivity and short turnaround. The method demonstrated good robustness and accuracy under the optimized pH, adsorption time, and MMIPs mass conditions. This combined MI-MDSPE/SERS-PLS strategy provides a practical route for rapid monitoring of MG in aquaculture settings.