Malachite green confirmation

Rushing and Hansen (504) described a sensitive analytical procedure for screening and confirmation of residues of malachite green, gentian violet, and their leuco analogs in catfish and trout tissues using liquid chromatographic separation and electrochemical, diode array, and fluorescence detection in series. 

When the coulometric detector was turned on, both leuco forms were completely oxidized to their nonfluorescing chromatic forms and thus vanished from the fluorescence channel. This disappearance was balanced by the arrearance of their chromatic forms in the diode array channel. The confirmation of malachite green, gentian violet, and tlieir leuco analogs in catfish and trout tissue could be based, therefore, on the correct retention times, the observation of the natural fluorescence of the leuco forms when the coulometric detector was turned off, the absence of the leuco form peaks in the 588 nm channel when the coulometric detector was off, the disappearance of the fluorescence of the leuco forms when the coulometric detector was on, the appearance of peaks of parent drugs formed by oxidation of the leuco forms in tlie. S88-nm diode array channel, and the correct ultraviolet-visible spectra maxima for all four peaks. 

Positive wet microchemical and microscopic identifications were permitted for the copper greens on only two of the Chinese silks. In both cases the result was the copper carbonate pigment malachite, which confirmed that Chinese copper greens were malachite and the Western ones were verdigris. A positive identification should be performed whenever conservation conditions permit it and trained personnel are available (7). 

Turnipseed, S.B. Roybal, J.E. Rupp, H.S. Hurlbut, J.A. Long, A.R. Particle-beam liquid-chromatography mass-spectrometry of triphenylmethane dyes—Application to confirmation of malachite green in incurred catfish tissue. J. Chromatogr. 1995, 670, 55-62. 

LC-PB-MS has been investigated as a potential confirmatory method for the determination of malachite green in incurred catfish tissue, " and cephapirin, furo-semide, and methylene blue in milk, kidney, and muscle tissue, respectively. LC-PB-MS has also been investigated for the analysis of ivermectin residues in bovine hver and milk. The specificity required for regulatory confirmation was obtained by monitoring the molecular... 

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