PVC膜离子选择电极检测下限的优化

价格低廉、携带方便、适用浓度宽、操作简单快捷、能耗低的离子选择电极在医院、分析实验室、野外等领域得到了越来越广泛的应用。尽管如此,由于PVC膜中存在的离子流严重破坏了更低检测下限的获取,限制了离子选择电极的进一步发展。因此,本文从减小甚至消除PVC膜中存在的离子流角度出发,系统论述了优化PVC膜离子选择电极检测下限的原理和优良策略,根据收集归纳的大量数据定量阐述传感膜组成的优化、电极组装和调制、应用旋转电极以及电流极化处理等对检测下限的优化提升作用,进一步总结出各种方法的改善规律,分析它们的优势和面临的问题。提出在PVC铸膜液中要突破传统配方,减小增塑剂和离子交换剂用量,以抑制传感膜两侧的离子流,同时外加电流补偿处理等也是降低电极检测下限的有效方法,对检测下限的改善最好的可降低5个数量级。这一总结为PVC膜离子选择电极的高性能化明确了研究方向。

Improvement of Lower Detection Limit of Ion-Selective Electrodes Based on PVC Membrane

Ion-selective electrodes(ISEs) based on polymeric membranes are characterized by small size,portability,low-energy consumption,and low cost,which are attractive features concerning practical applications.However,the lower detection limit is biased by the ion flux through PVC membrane,which limits the further development of ion-selective electrode.Therefore,the principles and attractive strategies to suppress such an ion flux to improve the lower detection limit of PVC membrane-based ion-selective electrodes are elaborated in this article.According to large amounts of data collected,the improvement of the detection limit via optimization of sensing membrane composition,electrode assembly and conditioning,electrode rotation,as well as current-polarized treatment,is quantitatively discussed.Furthermore,the modification regulations for expanding the lower detection limit are systematically summarized.The significant superiority and problems are analyzed.It is pointed out that we have to break the conventional PVC composition formulation via reducing the dosages of plasticizer and ion exchanger in order to largely depress the transmembrane ion flux.External-current application to the electrode is also an effective approach,among which,the best improvement for the lower detection limit can reach up to 5 orders of magnitude.This review reveals the future direction for developing the PVC membrane-based ion-selective electrodes with high performance.