DETERMINATION OF LEUCOGENTIAN VIOLET AND GENTIAN-VIOLET IN CATFISH TISSUE BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH VISIBLE DETECTION

A sensitive analytical procedure for the determination of residues of leucogentian violet (LGV) and gentian violet (GV) in catfish tissue is presented. Frozen (- 20 degrees C) catfish fillets were cut into chun ks and then blended in a Waring blendor. A 10-g amount of catfish musc le tissue was homogenized and extracted with acetonitrile-buffer, part itioned against methylene chloride, and cleaned up on tandem neutral a lumina and propylsulfonic acid cation-exchange solid-phase extraction cartridges. Samples of 100 mu l (0.5 g equiv.) were chromatographed is ocratically in 15 min using an acetonitrile-buffer mobile phase on a c yano phase column in-line with a post-column PbO2 oxidation reactor. T he PbO2 post-column reactor efficiently oxidized the LGV to the chroma tic GV permitting visible detection at 588 nm for both LGV and GV. Lin earity was demonstrated with standards over the range 0.5-50 ng per in jection. Recoveries of LGV and GV from catfish tissues fortified at 20 , 10, and 1 ng/g were 83.1 +/- 1.2, 78.4 +/- 4.0, 84 +/- 8 and 92.7 +/ - 1.8, 95.0 +/- 2.2, 93 +/- 2 (mean +/- S.D., n = 4), respectively.