Ultraviolet determination of chlordimeform in cattle dipping baths and sprays

A simple and reliable method has been developed for determining chlordimeform. A preliminary cleanup converts chlordimeform to its hydrochloride and removes ultraviolet-absorbing impurities. The aqueous acid phase containing chlordimeform. HCL is diluted and passed through a silica gel column. The column efflucent is used as the reference solution and a portion not eluted through silica gel is used as the sample solution in the spectrophotometer. The absorbance at 240 nm is measured, and chlordimeform concentration is determined from the calibration graph. The method applied to solutions of acaricides gives good results in the range of 0.02-0.06% w/v chlordimeform; higher concentrations may be determined by appropriate dilution.