Extraction Methods for Recovering Malachite Green and Leucomalachite Green

Malachite green (MG), a triphenylmethane dye, is carcinogenic, mutagenic, teratogenic, a respiratory toxin, and causes chromosomal fractures. It is not permitted for use as an aquaculture veterinary drug in a number of countries. Sensitive extraction methods for MG and leucomalachite green (LMG), which have long residence times in fish tissues, were developed. For LMG, the average recovery of liquid extraction (LE) ranged from 41.71 (yellowtail) to 71.60% (snakehead); the recovery of liquid-liquid extraction (LLE) was between 67.68 (yellowtail) and 83.68% (snakehead); and the average recovery of solid-phase extraction (SPE) ranged from 84.16 (yellowtail) to 92.92% (shrimp). The recovery of MG was less than 30% with SPE. However, the dye is found primarily as the colorless reduced leuco form in fish tissues.