Improved Detection Limits and Unbiased Selectivity Coefficients Obtained by Using Ion-Exchange Resins in the Inner Reference Solution of Ion-Selective Polymeric Membrane Electrodes
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- 作者：Wei Qin ; Titus Zwickl ; and Ernö ; Pretsch
- 刊名：Analytical Chemistry
- 出版年：2000
- 出版时间：July 15, 2000
- 年：2000
- 卷：72
- 期：14
- 页码：3236 - 3240
- 全文大小：70K
- 年卷期：v.72,no.14(July 15, 2000)
- ISSN：1520-6882
文摘
By using a high concentration of an interfering ion and alow one of the primary ion in the inner reference solutionof polymeric membrane ion-selective electrodes (ISEs),the lower detection limit may be improved and unbiasedthermodynamic selectivity coefficients may be obtained.To this purpose, a cation-exchange resin is used here tokeep the low concentration of the primary cation constant.Different compositions of the internal solution are required for obtaining optimal lower detection limits andunbiased selectivity coefficients. All ISEs studied here,i.e., for K+, Ca2+, and NH4+, based on valinomycin, ETH5234, and nonactin/monactin, respectively, show improved lower detection limits in the range of 10-7.6 (NH4+)to 10-8.8 M (Ca2+). Nernstian responses and, therefore,unbiased selectivity coefficients are obtained with the K+-ISE for the discriminated ions, Na+, Mg2+, and Ca2+.