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

Abstract

Malachite green (MG) has been used world-widely in aquaculture as a parasiticide or fungicide. Although MG performed successfully, it has not been permitted for use in aquaculture from European Union, USA, and Canada because of its carcinogenicity and mutagenicity. We developed a sensitive and specific method to determine MG and its principal metabolite, leucomalachite green (LMG), respectively by isotope dilution liquid chromatography mass spectrometry (ID-LC/MS). To enhance the extraction recovery of MG and LMG from fish tissue, an additional step, saponification, was introduced in sample preparation process to remove fat in sample extract, which hampered the performance of SPE columns. The residue of MG and LMG in fish was analyzed using liquid chromatography mass spectrometry in the selected ion monitoring (SIM) mode by monitoring at m/z 329 and 334 for MG and d5-MG and at m/z 331 and 337 for LMG and 13 C6-LMG, respectively. This method was validated by comparing with the value of the reference material provided by Laboratory Government Chemistry (LGC). The results agreed within the measurement uncertainty and the accuracy was much improved than the provided reference value by LGC.

Analysis of triphenylmethane dyes in seafood products: a review of extraction methods and determination by liquid chromatography coupled to mass spectrometry

“…McIlvaine solution (pH ¼ 3) and acetonitrile (ACN) 8,27,66,68,69 are among the most commonly solvents used in SLE (Table 1). In addition, aqueous ammonium acetate buffer (pH ranging from 3.6 to 4.5) followed by ACN 22,28,42,60,[70][71][72][73] can also be employed, and in other cases, only ACN is utilized. 11,33,74 In relation to pH, it is important to note that initial extraction from sh tissue was performed at low pH, in order to detach the MG ions from the matrix.…”

Chromatographic determination of fungicides in biological and environmental matrices. New achievements

“…A saponification step was introduced in the preparation of sample because the fat in the sample reduced the performance of the system. Measurements were performed on an HPLC‐MS instrument used in the SIM mode (Ahn et al , ). The stereoselective degradation of triadimenol was investigated in cucumber plants.…”

Malachite green in food

“…Because MG and LMG are sensitive to air and light, particular steps need to be taken to protect both analytical standards and sample residues from deterioration. Addition of ascorbic acid to standard solutions of LMG, to prevent photo‐oxidative demethylation, and of acetic acid to standard solutions of MG, to prevent transformation of MG to its carbinol form, has been applied (Hall et al., ; Ahn et al., ) and standard solutions are normally stored in amber bottles (Mitrowska et al., ; Hurtaud‐Pessel et al., ). In the case of sample treatment, protection from light is recommended and steps, such as addition of hydroxylamine hydrochloride as a reducing agent/antioxidant (Hurtaud‐Pessel et al., ) or use of acidified acetonitrile to reduce conversion of MG to its carbinol form (Hall et al., ) have been applied.…”

“…LC–MS methods using an ion‐trap detector have been developed for analysis of total MG in salmon and catfish, following oxidation of any LMG present in the sample to MG using DDQ, with reported LOD/LOQ values of < 0.15/0.15 μg/kg (Turnipseed et al., ), 0.24/0.75 μg/kg (Andersen et al., ) and 0.003/0.005 μg/kg (Martínez Bueno et al., ). Isotope dilution liquid chromatography/mass spectrometry (ID‐LC/MS), using deuterated and/or 13 C 6 ‐MG and ‐LMG, has been developed for fish, shrimp and shellfish (Doerge et al., ; Wu et al., ; Ahn et al., ). LOD values of 0.02 μg/kg for MG and of 0.5 μg/kg for LMG are reported (Doerge et al., ; Ahn et al., ) and CCα/CCβ values of 0.08/0.13 μg/kg for MG and of 0.05/0.09 μg/kg for LMG are reported (Wu et al., ).…”

“…Isotope dilution liquid chromatography/mass spectrometry (ID‐LC/MS), using deuterated and/or 13 C 6 ‐MG and ‐LMG, has been developed for fish, shrimp and shellfish (Doerge et al., ; Wu et al., ; Ahn et al., ). LOD values of 0.02 μg/kg for MG and of 0.5 μg/kg for LMG are reported (Doerge et al., ; Ahn et al., ) and CCα/CCβ values of 0.08/0.13 μg/kg for MG and of 0.05/0.09 μg/kg for LMG are reported (Wu et al., ). An accurate mass full‐scan TOF‐MS method has been applied to the analysis of shrimp, with reported LOD values of 0.06 and 0.60 μg/kg for MG and LMG, respectively (Villar‐Pulido et al., ).…”