Hassan S S, Mahmoud W H, Othman A H
Department of Chemistry, Faculty of Science, Ain Shams University, Cairo, Egypt.
Talanta. 1997 Jun;44(6):1087-94. doi: 10.1016/s0039-9140(96)02199-6.
A novel potentiometric membrane sensor for potassium ion based on the use of rifamycin as a neutral ionophore is described. The sensing membrane is formulated with 2 wt.% rifamycin-SV, 69 wt.% dibutylsebacate plasticizer and 29 wt.% PVC. Linear and stable potential response with near-Nernstian slope of 56.7 +/- 0.2 mV decade(-1) are obtained over the concentration range 1 x 10(-1)-3 x 10(-5) M K(+). The detection limit is 0.3 microg ml(-1) K(+), the response time is 10-30 s and the working pH range is 4-11. Responses of the sensor toward alkali and alkaline earth metal ions are in the order K(+) > Rb(+) > Cs(+) > Na(+) > NH(4)(+) > Ba(2+) > Mg(2+) > Ca(2+) > Sr(2+) > Li(+). The selectivity coefficient data reveal negligible interference from transition metal ions. Direct potentiometric determination of K(+) in the presence of 10-50-fold excess of alkali and alkaline earth metals gives results with an average recovery of 99.1%, and a mean standard deviation of 1.2%. The data agree fairly well with those obtained by flame photometry.
本文描述了一种基于利福霉素作为中性离子载体的新型钾离子电位膜传感器。传感膜由2 wt.%的利福霉素-SV、69 wt.%的癸二酸二丁酯增塑剂和29 wt.%的聚氯乙烯配制而成。在1×10⁻¹ - 3×10⁻⁵ M K⁺的浓度范围内，获得了线性且稳定的电位响应，近能斯特斜率为56.7±0.2 mV/decade⁻¹。检测限为0.3 μg ml⁻¹ K⁺，响应时间为10 - 30 s，工作pH范围为4 - 11。该传感器对碱金属和碱土金属离子的响应顺序为K⁺ > Rb⁺ > Cs⁺ > Na⁺ > NH₄⁺ > Ba²⁺ > Mg²⁺ > Ca²⁺ > Sr²⁺ > Li⁺。选择性系数数据表明过渡金属离子的干扰可忽略不计。在存在10 - 50倍过量碱金属和碱土金属的情况下直接电位法测定K⁺，结果的平均回收率为99.1%，平均标准偏差为1.2%。这些数据与火焰光度法获得的数据相当吻合。
