Malinowska E, Meyerhoff M E
Department of Analytical Chemistry, Faculty of Chemistry, Warsaw University of Technology, Poland.
Anal Chem. 1998 Apr 15;70(8):1477-88. doi: 10.1021/ac970761t.
The effect of the nonionic surfactants Brij 35 and Triton X-100 on the selectivity of neutral carrier-based ion-selective electrodes (ISEs) commonly used for measurements of electrolytes in whole blood is investigated. Studies are conducted with plasticized PVC membranes doped with several neutral ionophores commonly employed to prepare clinically useful potassium, calcium, and sodium ISEs. An observed increase in the electrodes' EMF values upon the addition of surfactant to the test solution suggests a change in the ion selectivity of the polymeric membranes in the presence of Brij 35 or Triton X-100. For membranes doped with K(+)-selective valinomycin, the effect of nonionic surfactants is relatively small. However, in the case of calcium-selective membranes prepared with ETH 1001 and ETH 129, nonionic surfactants, especially Triton X-100, decrease the selectivity for calcium over potassium cations by nearly 1 order of magnitude. Such behavior is even more dramatic for sodium-selective membranes, with the degree of surfactant-induced loss of ion selectivity dependent on the specific sodium ionophore employed, the lipophilic tetraphenylborate derivative content of the membrane, and the surfactant type. A detailed theoretical model is presented to explain the effect of nonionic surfactants on the EMF response function of cation-selective polymeric membrane electrodes. Experimental results are in good agreement with theoretical predictions based on known binding constants for ionophores and surfactants with given cations.
研究了非离子表面活性剂Brij 35和Triton X-100对全血电解质测量中常用的基于中性载体的离子选择性电极（ISE）选择性的影响。使用掺杂了几种常用于制备临床可用钾、钙和钠ISE的中性离子载体的增塑PVC膜进行了研究。在测试溶液中添加表面活性剂后，观察到电极的电动势（EMF）值增加，这表明在存在Brij 35或Triton X-100的情况下，聚合物膜的离子选择性发生了变化。对于掺杂K(+)选择性缬氨霉素的膜，非离子表面活性剂的影响相对较小。然而，在用ETH 1001和ETH 129制备的钙选择性膜的情况下，非离子表面活性剂，尤其是Triton X-100，使钙对钾阳离子的选择性降低了近1个数量级。对于钠选择性膜，这种行为更为显著，表面活性剂引起的离子选择性损失程度取决于所使用的特定钠离子载体、膜的亲脂性四苯基硼酸盐衍生物含量以及表面活性剂类型。提出了一个详细的理论模型来解释非离子表面活性剂对阳离子选择性聚合物膜电极EMF响应函数的影响。实验结果与基于离子载体和表面活性剂与给定阳离子的已知结合常数的理论预测高度一致。
