Optimization of the HPLC Method with Postcolumn Derivatization for Determination of Amprolium in Fodders at Contents Lower than 5 mg/kg

Abstract

An HPLC method was developed and validated for rapid determination of amprolium as an undesirable additive to final fodders. Amprolium is extracted from a sample with a mixture of methanol and dichloromethane and, after purification of the extract on a silica gel column, determined by ion-pair reverse-phase chromatography on C₈ with fluorescent detection after postcolumn derivatization with potassium hexacyanoferrate(III) in alkaline medium. The separation of amprolium on the C₈ reverse phase and its postcolumn derivatization were optimized. The limit of determination was 86 g.kg^-1, the repeatability 0.1 mg/kg and the yield of the method was 102 5.5 % at amprolium concentrations 0.5 - 5 mg/kg.. The repeatability was determined on real samples of final fodders.