除虫菊素含量分析法的改进

除虫菊素在除虫菊花或制剂中的含量分析方法,有容量分析法,即A.O.A.C.法(汞还原法),比色法,极谱分析法,色层分析法,纸上层析法,光谱分析法等。其中以容量分析法比较准确,世界各国多采用它。但这方法操作步骤多、费时久,在应用上感觉不便,最初一步提取手续,以石油醚用索氏抽出器抽提除虫菊素时,就须迴流八小时,因此有改进的必要,我们用一种改进抽出装置,经过多次试验,只须45

AN IMPROVED METHOD FOR THE DETERMINATION OF PYRETHRIN

The A. O. A. C. official method for assaying pyrethrin is in wide use as it has been considered to be reliable and accurate. However, the precedure is rather tedious and time-consuming. The authors propose to modify the method, by (1) using a modified extraction device, the sample can be extracted completely within one hour with petroleum ether, and (2) directly titrating chrysanthemum monocarboxylic acid and chrysanthemum dicarboxylic acid, subsequently extracted with petroleum ether and ether respectively, in these organic solvents with potassium methoxide solution using bromothymol blue as indicator. Two samples of pyrethrum powder and five samples of pyrethrum extract preparations were determined, giving results agreed well with those obtained by A. O. A. C. official method.