A. Ion-selective electrodes based on electropolymerized crown ethers. B. Detection of hydrogen peroxide at a cadmium-modified platinum electrode in flow injection analysi

Section A. Ion selective electrodes based on the immobilization of crown ethers in liquid membranes and inert solid polymer films are common. So far, however no Sr$sp{+2}$ selective electrode with a high rejection of alkali-metal as well as the other alkaline-earth metal cations, based on electropolymerized crown ethers, has been described.;The work in this thesis describes the potential response behavior of a strontium doped poly(dibenzo-18-crown-6) film electrode, to strontium ion concentration in solution has been examined. The effect of polymerization conditions on the characteristics of the response is discussed. The performance of the electrode with respect to electrode reproducibility, response stability and regeneration is also studied. As stated the calibration plots for electrode have an unexpected slope of 31-32 mv per potassium concentration decade at 25$spcirc$C and 58-59 mv per strontium (II) concentration per decade. The selectivity coefficients for this polymeric electrode for most of the potential interferants are in the order of 10$sp{-3}$. This polymeric film electrode has a relatively fast response, and is easy to prepare and has a reasonable lifetime.;Section B. The analysis of hydrogen peroxide is of great importance in the studies of fuel cells, photocatalytic water splitting, bioelectrochemistry, etc. The polished platinum-electrode has been used to detect hydrogen peroxide at +0.93 V vs. SCE in a supporting electrolyte of 1 M sulfuric acid. But under these potential conditions, various interferences from cations and organic compounds have been observed. The modification of glassy carbon-electrode, by cycling in a solution of Na$sb2$IrCl$sb6$, PdCl$sb2$ and HCl, has previously been reported. This modified electrode was used in linear scan voltammetry to detect hydrogen peroxide.;The work in this thesis describes a cadmium-modified platinum electrode (Cd-CME) as an electrochemical sensor for hydrogen peroxide. The performance of this sensor is evaluated in FIA and its response towards hydrogen peroxide is studied. Comparison of this Cd-CME is done with a simple polished platinum electrode.