Analysis of malachite green and metabolites in fish using liquid chromatography atmospheric pressure chemical ionization mass spectrometry

Abstract

Malachite green (MG), a traditional agent used in aquaculture, is structurally related to other carcinogenic triphenylmethane dyes. Although MG is not approved for use in aquaculture, its low cost and high efficacy make illicit use likely. We developed sensitive and specific methods for determination of MG and its principal metabolite, leucoMG (LMG), in edible fish tissues using isotope dilution liquid chromatography atmosphere pressure chemical ionization mass spectrometry. MG and LMG concentrations were measured in filets from catfish treated with MG under putative use conditions (ca. 250 and 1000 ppb, respectively) and from commercial trout samples (0-3 and 0-96 ppb, respectively). Concentrations of LMG in edible fish tissues always exceeded those of MG. A rapid cone voltage switching acquisition procedure was used to simultaneously produce molecular ions for quantification and diagnostic fragment ions for confirmation of MG and metabolites. The accurate and precise agreement between diagnostic ion intensity ratios produced by LMG in authentic standards and incurred fish samples was used to unambiguously confirm the presence of LMG in edible fish tissue. This suggested the validity of using LMG as a marker residue for regulatory determination of MG misuse. Additional metabolites derived from oxidative metabolism of MG or LMG (demethylation and N-oxygenation) were identified in catfish and trout filets, including a primary arylamine which is structurally related to known carcinogens. The ability to simultaneously quantify residues of MG and LMG, and to confirm the chemical structure of a marker residue by using LC/MS, suggests that this procedure may be useful in monitoring the food supply for the unauthorized use of MG in aquaculture.

Biotransformation of Malachite Green by the FungusCunninghamella elegans

“…Under these conditions, the mass spectra consisted primarily of molecular ions (protonated molecules for leucomalachite green and the demethylated derivatives and cationic molecules for malachite green and its derivatives). Based on previous reports (11,12), these peaks correspond to malachite green (m/z 329) and its mono-, di-, and tri-desmethyl derivatives (m/z 315, 301, and 287, respectively) and leucomalachite green (m/z 331) and its mono-, di-, tri-, and tetra-desmethyl derivatives (m/z 317, 303, 289, and 275, respectively). The metabolites extracted from the culture supernatants were similar to those obtained from mycelium-extracted samples, except for malachite green N-oxide (m/z 345; retention time, 9.21 min), which was detected only in the mycelia.…”

“…An isocratic solvent system (solvent A/solvent B ratio ϭ 40:60) was also used when the disappearance of malachite green was moni-tored. Conditions for liquid chromatography-atmospheric pressure chemical ionization-MS analysis were as described previously (12).…”

Can Malachite Green Concentrations Cause Hepatic Toxic Effects in Adult Albino Rats: Histological, Biochemical and Immunohistochemical

“…MG is extremely cytotoxic to mammalian cells, as it induces free radical formation, acts as a potent liver tumor promoter and induces malignant transformation [8]. Although the use of this dye has been banned in several countries [9][10][11][12] and not approved by US Food and Drug Administration, it is still being used in many parts of the world including Egypt due to its low cost, ready availability and efficacy [13,14].…”

Accurate Determination of Malachite Green and Leucomalachite Green in Fish using Isotope Dilution Liquid Chromatography/Mass Spectrometry (ID-LC/MS)

“…Hence, the detection of MG and LMG by mass spectrometry without the oxidation step was accomplished. [16][17][18][19] The other techniques using GC-MS, 20,21 electrochemical detection, 22 and spectrometry 23,24 have been achieved also. In this study, an experimental approach to improve accuracy for determination of MG and LMG in fish tissue has been developed using isotope dilution liquid chromatography mass spectrometry (ID-LC/MS).…”