DETERMINATION OF DICLAZURIL IN ANIMAL FEED BY LIQUID-CHROMATOGRAPHY

A method is described for the determination of diclazuril (Janssen Research Compound R64433; trademark Clinacox) in chicken feed at the 1 mg kg-1 level. Compound R062646, a structure analogous to diclazuril, was used as the internal standard. The drug was extracted from food with acidified methanol. Diclazuril was then isolated by means of solid-phase extraction with a cartridge containing a C18 phase. The eluate was evaporated and the residue redissolved in dimethylformamide. An aliquot was injected onto a reversed-phase high-performance liquid chromatographic column and the drug substance quantified at 280 nm by an ultraviolet detector. Extraction (absolute) recoveries of 85% for both internal standard and diclazuril were obtained. The method is suitable for diclazuril concentrations ranging from 0.1 to 1.5 mg kg-1. Method validation data are presented.