Studys On Ion-Selective Electrode Of Thiocyanate And Salicylate Based On Schiff Base Metallic Complexes As Neutral Carriers

The application of ion-selective electrode is a typical kind of potential analytical method that acts as an indicator electrode, which is also an important branch of the electrochemical analysis. The ion-selective electrode is a kind of mature chemical sensor applied very widely and with long time. The PVC membrane ion-selective electrode has many virtues such as simple construction, low cost, simple pretreat and rapidly online determination and so on. So as a conventional detecting approach to a variety of cations and anions, this kind of electrode is applied widely in the field of clinical medicine, environmental science, industrial production and such like. Design, synthesis and application of neutral carriers of high selectivity and sensitivity are main research interests in the ion-selective electrode study fields, so it has important theory and practice meaning that search and research electrical activity material that can recognize the special target ion with more performance and apply this material to construct the PVC membrane ion-selective electrode. Recently, studies on ion-selective electrodes with anti-Hofmeister selectivity patern are an important and interesting project in the fields of electroanalytical chemistry and electrochemistry sensor. Shortly after the peoples discovered that the Shiff base metallic complexes have the special selective to the specific anion, the study of this sort of electrode that there are widely application prospect has been a hotspots in this field.The thesis has given an overview of elementary theory of the ion-selectiveelectrode, introduction to the ion-selective electrode's development and existing actuality. A new Highly salicylate-selective PVC membrane electrode based on o-salicyladehyde- aminophenol cobalt(II) complex [Co(II)-SAAP] as a neutral carrier is described, which displays a preferential potentiometric response to salicylate and an anti-Hofineister selectivity sequence in following order: Sal'> C1C?4"> SCN> I"> NO2"> NO3"> Br"> Cr> SO32"> SO42". The electrode exhibits near Nernstian potential linear range of 9.0* 10"*—1.0*10"' mol/mL with a detection limit of 5.0X10"6 mol/mL and a slope of-54.3 mV/decade in pH 5.0 of phosphorate buffer solution at 20°C. At the same time, a new highly selective thiocyanate electrode based on Copper(II) Complex with 2'-(2-Thienylidence)-Hydroxybenzoylhydrazide [Cu(II)-HTBH] as neutral carrier is developed, which displays an anti-Hofmeister selectivity sequence: SCN> Sal" > CIO4'> I" > Br" > NO3" > Cl" > NO2" > SO32" > SO42" > H2PO4". The electrode exhibits Nernstian potential linear range to thiocyanate from 1.0x10"' to 5.0><10"6 mol/L with a detection limit 1.2*10"6 mol/L and a slope of 53.4 mV/dec in pH 5.0 of phosphorate buffer solution at 25 "C. To the two sorts of electrodes, the response mechanism is discussed in view of the a.c. impedance technique and the UV spectroscopy technique. These deviations result from the direct interaction between the central metal and the analyte ion and steric effect associated with the structure of the carrier. The electrode s have the advantages of simplicity, fast response, fair stability and reproducibility and low detection limit. The electrode s can be applied to analysis of medicine and waste water and the result obtained is fair agreement with the result given by HPLC methods or precipitation method.This paper explored two kinds of new the Shiff base metallic complexes as the ionophores of the ion-selective electrode, which have provided a sort of rapidly determination method and have high selective to salicylate and thiocyanate in the intricate and actual sample system for determining medicine, waste water and so on.