DETERMINATION OF GENTIAN-VIOLET IN HUMAN URINE AND POULTRY FEED BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION USING A CARBON-FIBER MICROELECTRODE FLOW CELL

A sensitive and relatively selective high performance liquid chromatog raphic method for the determination of Gentian Violet (GV) in human ur ine and chicken feed is described. The method is based on solid-phase extraction, with subsequent reversed-phase chromatographic separation on a cyano column and amperometric detection using a carbon fibre micr oelectrode flow cell operated at +1.3 V. The peak currents were direct ly proportional to GV concentration over the concentration range 1-30 ppb (for urine samples analysis) and 1-20 ppm for poultry feed analysi s. Using this method, the minimum detectable concentration was estimat ed to be 0.5 ppb. The method was applied successfully to the determina tion of GV in human urine and in chicken feed, and it was concluded th at the method could be applied to the quantitative analysis of GV in t he presence of its major metabolite, leuco GV. In the proposed procedu re, the occurrence of matrix effects during urine analysis was signifi cant. The electrochemical pretreatment regime described in this paper was used to overcome these effects. Recovery studies were performed on both the human urine and chicken feed samples. The recovery of GV ran ged from 92 to 96% in both matrices, with a relative standard deviatio n of less than 5.5%.