engleski

Optimization of PO43-selective electrode

Analytical methods for a simple and selective phosphate determination attract a lot of attention, since phosphate occurs in many consumer products, it directly associated with environmental pollution and is vital in many biocemichal processes. Many investi-gation efforts have been directed to the development of a phosphate selective sensor, but a routinely applicable device has not been designed so far. An attempt to improve the characteristics of a recently developed phosphate selective electrode based on silver phospahate membrane is presented. The membrane was pre-pared by coating a thin layer of silver on platinium with a layer of Ag3PO4, using an electrochemical procedure [1]. The electrode was suitable for the determination of PO43- in the presence of HPO42- and H2PO4- in the activity range 3 10-9 < a(PO43-)<3 10-5 Mayor drawbacks were interferences by Cl- and H+ and a rather short lifetime. The performance of the electrode can be further improved by covering the membrane with a thin protective PVC film. The effect of the PVC film and the dependence of its thick-ness on the response time, reproducibility, lifetime, working range and selectivity are discussed. As a further step in improving the electrode, the use of other various poly-meric coanting materials is considered. [1]1. Vermes and E.W. Grabner, J. electronal. Chem. 284 (1990) 315

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