title: Determination of residues of malachite green in aquatic animals.
abstract: Residues of malachite green (MG) were extracted from homogenized animal tissues with a mixture of McIlvaine buffer (pH 3.0)-acetonitrile, and purified over an aromatic sulfonic acid solid-phase extraction column followed by HPLC or LC-ESI-MS-MS analysis. Ascorbic acid and N,N,N',N'-tetramethyl-1,4-phenylenediamine dihydrochloride were added to reduce de-methylation of the dye. Responses were recorded at 620 nm (HPLC) or by multiple-reaction-monitoring (LC-MS-MS) after post-column oxidation using PbO(2). MG and its primary metabolite leuco-malachite green (LMG) were successfully determined at 2.5-2000 microg/kg in catfish, eel, rainbow trout, salmon, tropical prawns and turbot, with a limit of detection at 1 microg/kg (HPLC) and 0.2 microg/kg (LC-MS-MS) for both MG and LMG. Recoveries for LMG were between 86+/-15% (prawn) and 105+/-14% (eel). Freeze-thawing cycles, and storage at 4 degrees C and -20 degrees C affected the recovery of both MG and LMG. Analyses of eel, trout and (processed) salmon field samples collected at local retailers, fish-market and -shops demonstrated trace levels of MG-residues.
authors.affiliation: Department of Public Health and Food Safety, Faculty of Veterinary Medicine, Utrecht University, P.O. Box 80.175, NL-3508 TD Utrecht, The Netherlands. a.abergwerff@vet.uu.nl
authors.forename: Aldert A
authors.initials: AA
authors.lastname: Bergwerff
authors.forename: Peter
authors.initials: P
authors.lastname: Scherpenisse
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004396:Coloring Agents / Q000032:analysis*; D003445:Crustacea; D005399:Fishes; D013058:Mass Spectrometry / Q000379:methods; D008974:Mollusca; D015203:Reproducibility of Results; D012394:Rosaniline Dyes / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D004396:Coloring Agents; D012394:Rosaniline Dyes; D014874:Water Pollutants, Chemical; C005095:malachite green