The determination of chlorhydroxyquinoline in medicated pig feeds. Part II. Ultraviolet spectrophotometric batching assay and gas-chromatographic assay for mono- and dichloro components

Abstract

Two procedures have been developed for determining chlorhydroxyquinoline (halquinol) in pig feed medicated at a level of 120 p.p.m. The ultraviolet spectrophotometric procedure can be used to determine halquinol and the gas-liquid chromatographic procedure to determine specifically the 5,7-dichloro- and the combined 5- and 7-chloroquinolin-8-ol components. Halquinol was found to react with copper during the initial extraction with chloroform, thus preventing formation of the silyl ether prior to gas-liquid chromatography. Partitioning the chloroform extract with dilute mineral acid so as to cause dissociation of the chelate and adding EDTA before back-extraction into dichloromethane overcame this problem.