Capillary electrophoresis coupled with molecularly imprinted polymer solid phase extraction for screening malachite green and related substances

In this study, we report the development of a green analytical approach for concurrent determination of different triphenylmethane dyes in water samples collected from shrimp and fish farming, as well as their leuco-metabolites in fish. This is based on capillary electrophoresis instrumentation, coupled with capacitively coupled contactless conductivity detection. Our approach was applied to screen malachite green, crystal violet, leucomalachite green and leucocrystal violet in aquatic samples with detection limits down to 0.50 mg/L, 0.50 mg/L, 0.30 mg/L, and 0.30 mg/L, respectively. A method for sample pretreatment and enrichment using molecularly imprinted polymers was developed to preconcentrate the extracted malachite green and leucomalachite green from fish and fish-floss samples prior to determination of these compounds, allowing detection limits down to 20,0 µg/kg. Accuracy assessment with LC-MS/MS was implemented, demonstrating good agreement (deviation less than 10 %) between results obtained with our approach and those from the reference method.