| Research Abstract |
In order to obtain the information on the amount, existing state, distribution, and circulation of trace elements in environment, the sensitive and selective methods of analysis are still desired. Kinetic methods of analysis based on catalytic reactions have been utilized to trace analysis for various elements because of their extremely high sensitivity, low limit of detection and selectivity. By using the catalytic-kinetic methods of analysis, as little as 10^<-9> - 10^<-11> M of metal ions can easily be determined. The adaptation of flow injection analysis (FIA) to catalytic methods can lead to many advantages such as higher precision and rapid sample throughput. We thus developed the kinetic-catalytic methods of analysis for iron(II, III), cobalt(II), copper(II), vanadium(IV, V) and nitrite ions by FIA methods. Indicator reactions used in this work are as follows : a) Oxitative coupling reaction of 3-methyl-2-benzothiazolinone hydrazone (MBTH) with N,N-dimethylaniline (DMA) and/or modifies Trinder's reagent for Fe(II,III) and/or for Co(II), b) Oxidative coupling reaction of N-phenyl-p-phenylenediamine with DMA for Cu(II) and/or m-phenylenediamine for NO_<2->, c) Hydrogen peroxide oxidation of 3,3', 5,5'-tetramethylbenzidine (TMBZ) for Fe(II, III), d) Bromate oxidation of N-3-sulfopropyl-TMBZ for V(TV, V), e) Hydrogen peroxide oxidation of MBTH for Fe(II,III) and f) Redox reaction of iron(III) with cysteine in the presence of phen for Cu(ll). One of the possibilites for further increasing the sensitivity of the kinetic-catalytic methods is the application of activators. Phen, sulfosulycylate and Tiron acted as effective activators for the catalysis of Fe(II, III), V(IV,V) and Co(IJ), respectively. These methods have been successfully applied to the determination of natural water samples and reference materials.
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