Gas Chromatographic/Mass Spectrometric Confirmation of Leucomalachite Green in Catfish (Ictalurus punctatus) Tissue

Abstract

Abstract A gas chromatographic/mass spectrometric (GC/MS) method was developed to confirm the presence of leucomalachite green (LMG), a metabolite of the triphenylmethane dye malachite green (MG), in catfish tissue. Residues were isolated according to a previously described liquid chromatographic (LC)A/IS spectrometric analysis of MG and LMG in fish. In our isolation procedure, analytes are extracted from tissue with acetonitrile–buffer, partitioned into CH2CI2, and applied to neutral alumina and propylsulfonic acid solid-phase extraction cartridges. Before GC/MS analysis, extracts prepared for the LC determinative method are eluted from a cyano solid-phase extraction cartridge, extracted into organic solvent, and concentrated for GC/MS analysis. Selected ion monitoring was performed by using 5 diagnostic ions (m/z 330,329,253,210, and 165) of LMG. The method was validated by confirming LMG in tissue fortified with mixtures of MG and LMG (5 and 10 ng/g each) and in tissue from fish that had been exposed to low levels of MG.