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A catalytic polarographic method for the determination of microgram quantities of Ce(IV) is developed based on the catalytic currents of cerium(IV) in the presence of NH 4 Cl-NH 4 OH at pH 6.2 with piperazine. Piperazine produces catalytic current with Ce(IV) at peak potential-0.1 to-0.6 V vs. SCE. The procedure was applied for the estimation of Ce(IV) in water samples. The method is simple, sensitive and free from interference of many metal ions.

Abstract:Two new ligands, ammonium 2,6-dimethyl morpholine dithiocarbamate (ADMM-DTC) and ammonium 3-methyl piperdine dithiocarbamate (AMP-DTC) were synthesized in the laboratory. The method was based on chelation of manganese(II) with ADMM-DTC/AMP-DTC in the presence of NH 4 OH at pH 6.2 and 6.8 to produce catalytic hydrogen currents at -0.72 V and -0.62 V vs. SCE respectively and prior detected by D.C poarography. Optimized polarographic conditions were established by studying effect of pH, supporting electrolyte (NH 4 Cl), ligand and metal ion concentrations and effect of adverse ions on peak height to improve the sensitivity, selectivity and detection limits of the present method. This technique is successfully applied for the analysis of manganese(II) in different matrices with recoveries ranging from 97 -99% and the results obtained were comparable with the differential pulse polarography (DPP).

A facile, rapid and sensitive catalytic hydrogen signal method has been developed for the analysis of chromium(VI) using two new ligands Ammonium N-phenylpiperazine-1-carbodithioate (APP-CDT) and Ammonium N-benzylpiperidine-1-carbodithioate (ABP-CDT) were synthesized. The method was depending on the reaction of chromium(VI) with APP-CDT and ABP-CDT at pH 8.6 and 7.8 respectively in supporting electrolyte (NH 4 Cl-NH 4 OH) medium. The resulting oxidation peaks were obtained at -1.68V and -1.60 V vs SCE respectively, due to the catalytic hydrogen signals (CHS's). Different experimental conditions such as pH effects, background electrolyte (NH 4 Cl-NH 4 OH) effects and carbodithioate (CDT) and chromium(VI) ion effects were studied. The present technique was successfully used to detect chromium(VI) in several environmental, biological samples. It was demonstrated that the obtained recovery percentages (95-99%) were comparable to the Atomic Absorption Spectrophotometry (AAS) method.

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