Ultraviolet Spectrophotometric and Gas Chromatographic Methods for Ronnel in Feeds

Abstract Two new methods for ronnel in feeds at levels of 0.035-0.60% ronnel were developed and studied by 10 collaborators. Methods involve extraction of the sample (with chloroform for ultraviolet measurement or with acetone for gas chromatographic measurement) followed by Florisil cleanup of the extracts. Both methods measure true ronnel. The described methods are simpler and give better ronnel recoveries (92— 105%) than the present official, first action steam distillation method. Agreement between laboratories was good; coefficients of variation were 4.1—11.1%. Several collaborators encountered difficulty with Florisil cleanup at the low level (0.03% ronnel). It is recommended that study be continued on the standardization of Florisil