Cox J A, Bhatnagar A, Francis R W
Department of Chemistry and Biochemistry, Southern Illinois University at Carbondale, Carbondale, IL 62901, U.S.A.
Talanta. 1986 Sep;33(9):713-6. doi: 10.1016/0039-9140(86)80171-0.
When two aqueous solutions are separated by a liquid membrane that contains a complexing agent which is a conjugate base of a weak acid, a metal ion can be transported from the solution of the higher pH against its concentration gradient into the more acidic solution. With Cu(II) as the analyte and a liquid membrane consisting of a mixture of oximes dissolved in kerosene, enrichment factors for a prescribed dialysis time in a simple experimental apparatus were nearly independent of Cu(II) concentration over the range 10(-4)-10(-7)M. With 0.1M hydrochloric acid as the receiver, the enrichment factor was independent of ionic strength and of sample pH in the range 4-9. The effect of sample pH on the interference of Fe(III) was examined. With a pH-2.5 formate buffer, the enrichment factor for Cu(II) decreased as the Fe(III) concentration increased, but in a pH-9.3 ammonium buffer, 0.14 mM Fe(III) did not interfere with the transport of Cu(II) from a 16muM copper sample.
当两种水溶液被含有络合剂（一种弱酸的共轭碱）的液膜隔开时，金属离子可以从较高pH值的溶液中逆着其浓度梯度转运到酸性更强的溶液中。以Cu(II)作为分析物，使用由溶解在煤油中的肟混合物组成的液膜，在一个简单的实验装置中，规定透析时间的富集因子在10(-4)-10(-7)M范围内几乎与Cu(II)浓度无关。以0.1M盐酸作为接收液时，富集因子与离子强度以及4-9范围内的样品pH值无关。研究了样品pH值对Fe(III)干扰的影响。在pH为2.5的甲酸盐缓冲液中，随着Fe(III)浓度的增加，Cu(II)的富集因子降低，但在pH为9.3的铵缓冲液中，0.14 mM的Fe(III)不会干扰16μM铜样品中Cu(II)的转运。
