The determination of chlorhydroxyquinoline in medicated pig feeds

A method has been developed for the determination of chlorhydroxyquinoline (Halquinol) in medicated pig feeds. Because of the interference by feed constituents in simple spectrophotometric and polarographic assay procedures, a spectrofluorimetric procedure is recommended. Spectrofluorimetric measurements are taken in a methanolic solvent containing 5 per cent. of chloroform, and the fluorescence of chlorhydroxyquinoline, as its magnesium chelate, is measured at 500 nm, with an excitation wavelength of 402 nm. Cyanide is used to suppress interference from copper and zinc salts that are commonly added to these feeds. The procedure is not affected by the presence of other feed additives, such as dimetridazole and arsanilic acid.