Rapid analysis of malachite green and leucomalachite green in fish muscles with surface-enhanced resonance Raman scattering

Surface-enhanced resonance Raman scattering (SERRS) coupled with gold nanospheres was applied for rapid analysis of the hazardous substances malachite green (MG) and leucomalachite green (LMG) in fish muscle tissues. The lowest concentration of MG that could be detected was 0.5 ng mL−1 with high linear correlation (R2 = 0.970-0.998) between MG concentration and intensities of characteristic Raman peaks. A simplified sample preparation method taking less than 1 h for recovering MG and LMG in fish fillets was developed for SERRS analysis, and 4-8 samples could be handled in parallel. MG and LMG could be detected in extracts of tilapia fish fillets at as low as 2 ng g−1 with SERRS and a simple principle component analysis method. For six other fish species, the lowest detectable concentration of MG ranged from 1 ng g−1 to 10 ng g−1. This study provides a new sensitive approach for the detection of trace amounts of the prohibited drugs MG and LMG in muscle food, which has the potential for rapidly screening a large number of samples.