High pressure liquid chromatographic detection and estimation of furazolidone and nitrofurazone in animal feeds.

The feed sample is extracted with acetone or dimethylformamide-acetone (1 + 1) and the filtered extracts are evaporated to dryness. The residue is dissolved in chloroform and transferred to a silica gel column. The nitrofurans are eluted with methanol-chloroform (50 + 50). A portion of the eluate is evaporated to dryness and the residue is redissolved in a small volume of methanol. Aliquots of the methanolic solution are injected into a liquid chromatograph with a muBondapak C18 column, using 30% acetonitrile as the eluting solvent and ultraviolet detection at 365 nm. Several samples spiked with 0.5--50 ppm furazolidone or nitrofurazone and 2 commercial samples were analyzed by the proposed method.