卵磷脂络合碘的制备及电位法测定碘的含量

Synthesis of iodized lecithin and determination of iodine by potentiometric titration

目的:合成了卵磷脂络合碘,并建立一种以电位滴定法测定卵磷脂络合碘中碘含量的方法。方法:以卵磷脂和碘为原料,乙醚为反应溶剂,三者混合并充分搅拌,回收乙醚得卵磷脂络合碘。采用氢氧化钾乙醇溶液(v/v,1∶5)回流,水解卵磷脂络合碘,以0.05 mol.L-1硝酸银为标准溶液进行滴定,用电位变化判断滴定终点,从而测定其中碘的含量。结果与结论:合成方法简单,收率高(>96%),合成工艺中使用的乙醚可回收使用,无污染。所建立的电位滴定法测定卵磷脂络合碘中碘的含量,滴定突跃明显,平均回收率为100.1%(RSD为0.21%),精密度RSD为0.34%(n=6),结果令人满意。

Objective： To synthesize iodized lecithin and establish a potent iometric tritration method for the determination of iodine in iodized lecithin. Methods： The synthetic procedure was started by mixing lecithin and iodine in ether; after sufficiently stirring the mixture, iodized lecithin was obtained by evaporating ether. Iodine in iodized lecithin was hydrolyzed by potassium hydroxide in ethanol （v/ v, 1 ： 5）, 0. 05 mol· L^-1 silver nitrate was selected as the standard solution, and the titration end point was indicated by the change of electric potential. Results and Conclusions： The synthetic method was simple with high yield （ 〉 96% ）. Ether as a solvent was recycled without pollution to the environment. Established potentiometric titration showed an obvious titration jump, the average recovery was 100. 1% （RSD =0. 21% ） and the precision was 0. 34% （ n =6）. The quatitative analytical method was accurate and suitable to determine iodine in iodized lecithin.