Determination of Gentian Violet in human urine and poultry feed by high performance liquid chromatography with electrochemical detection using a carbon fibre microelectrode flow cell

A sensitive and relatively selective high performance liquid chromatographic method for the determination of Gentian Violet (GV) in human urine 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 microelectrode flow cell operated at + 1.3 V. The peak currents were directly proportional to GV concentration over the concentration range 1-30 ppb (for urine samples analysis) and 1-20 ppm for poultry feed analysis. Using this method, the minimum detectable concentration was estimated to be 0.5 ppb. The method was applied successfully to the determination of GV in human urine and in chicken feed, and it was concluded that the method could be applied to the quantitative analysis of GV in the presence of its major metabolite, leuco GV. In the proposed procedure, the occurrence of matrix effects during urine analysis was significant. 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 ranged from 92 to 96% in both matrices, with a relative standard deviation of less than 5.5%.