肥皂中含磷量的测定

针对肥皂类洗涤用品，探讨了应用磷钼酸显色法进行含磷量的测定。由于肥皂中含有大量脂肪酸钠(钾)，对磷的显色测定产生严重的背景干扰，因此如何消除脂肪酸盐的干扰是研究的重点。提出了将肥皂试样酸化，使脂肪酸盐成为不溶于水的脂肪酸，然后用石油醚对析出的脂肪酸进行液-液萃取，去除脂肪酸，最后用磷钼酸显色法检验水相中残留磷的量。实验通过向待测样品中定量加入磷酸二氢钾，验证了方法准确度，测定结果的绝对误差小于0．1％，标准偏差为0．0024％。方法适用于肥皂、肥皂粉等含有大量脂肪酸的洗涤用品。

Determination of phosphate content in soap

The application of phosphomolybdic acid colorimetry method in the determination of phosphate content in soap-based laundry products was discussed.Since there are a lot of fatty acid sodium(potassium)salts that result-in severe background interference in the determination,the elimination of such interference is the focus of the study.The resolution has been developed by acidifying the soap-based sample,converting to water insoluble free fatty acid phase and following by petroleum ether extraction,then the remaining aqueous solution phase can be treated by the phospho-molybdic acid colormetry.The accuracy of this method is calibrated by control test with addition of given amount of potassium phosphate.The results show that the absolute error is less than 0.1 % while the standard deviation is around 0.002?4 %.