浊点萃取-光度法测定卷烟纸中磷酸盐

建立了分光光度法测定卷烟纸中痕量磷酸盐的浊点萃取分离富集体系。磷酸根离子在酸性介质中与钼酸盐反应生成磷钼酸盐,可溶性磷钼酸盐与阳离子表面活性剂溴化十六烷基三甲基铵(CTAB)形成疏水性的离子对缔合物,进行浊点萃取,采用光度法测定。研究了溶液的酸度、试剂用量、平衡时间、平衡温度、干扰离子对浊点萃取效果的影响,并得到最佳测定条件:5%的Triton X-114用量0.8m L、平衡温度60℃、平衡时间15min,将表面活性剂富集相用乙醇分散稀释,应用紫外-可见分光光度计在700 nm波长处测定。测定的线性范围为5.0~500 ng/m L,方法的检出限为0.5ng/m L,相对标准偏差(RSD)为1.1%~3.5%。

Cloud Point Extraction-Spectrophotometric Determination of Phosphate in Cigarette Paper

A cloud point extractionseparation and enrichment combining with(CPE) spectrophotometric method was established for the determination of trace amounts of phosphate in cigarette paper.Phosphomolybdate was obtained in acidic medium through the reaction between phosphate and molybdate.The solublephosphomolybdate and cationic surfactant bromide of cetyltrimethyl ammonium(CTAB) can form a hydrophobic ion-pair associate complex,which can be separated and enriched through CPE and detected by photometric method.The effect of solution acidity,reagent consumption,balance time,equilibrium temperature,interfering ions on efficiency of CPE was investigated,and the optimal experimental conditions were obtained by using 0.8 m L of Triton X-114(5%) as extraction agent and exacted for 15 min at 60 ℃,then the enriched phase of surfactant was dilute and dispersed by ethanol,and detected by UV-vis spectrophotometry at 700 nm.Under the optimum condition,the linearity ranged from 5.0 to 500 ng m L-1and the limit of detection(LOD) was 0.5 ng m L-1,the relative standard deviations(RSDs) were in the range from 1.1%to 6.9%.