Analysis of malachite green and leuco-malachite green in sea food

To determine malachite green and leuco-malachite green residues in sea food, a liquid chromatographic method has been optimized. The target compounds were extracted in the homogenized edible tissues with a mixture of Mcllvaine buffer-acetonitrile and partitioned against dichloromethane. After concentrating the lower layer, the resulting residues were re-dissolved in methanol and analyzed by the HPLC with visible detector at 620 nm using acetonitrile-acetate buffer. For the analysis of leuco-malachite green with malachite green simultaneously, post-column packed with lead(tV) oxide was used for oxidizing leuco-malachite green to malachite green. The correlation coefficients(r(2)) was 0.9989 for malachite green, and 0.9995 for leuco-malachite green. The limit of detection was 0.005 mg/kg for the combined of malachite green and leuco-malachite green at signal/noise >= 3. The recovery rate was within a reliable range of 84-98% (CV 3-16%). Leuco-malachite green were detected in carp and crusian carp.