NOPR Collection:

Electrochemical proof of the single bond character of the N-N bonds in some 1,2,4-triazines

2016-07-20T04:43:10Z

Title: Electrochemical proof of the single bond character of the N-N bonds in some 1,2,4-triazines Authors: Ludvik, J; Zuman, P Abstract: Whereas in molecules containing grouping X=C-C=Y (X,Y = C, O, N, S) delocalization of electrons takes place. In compounds containing the grouping C=N-N=C the central N-N bond has a single bond character and conjugation does not play a role. The single bond character of the N(1)-N(2) bond in 1 ,2,4- triazin-5-ones has been confirmed based on identity of reduction potential of the 1 ,6-azomethine bond in the parent compound and of the 1,6-C=N bond in the corresponding 2,3- dihydroderivative. Lack of delocalization has also been proved for acyclic azines. Comparison of half-wave or peak potentials is a simple and efficient way to prove or disprove the role of the delocalization of electrons over the studied molecule. Page(s): 847-848

Use of voltammetric methods for the analysis of trace metals in engine oils

2016-07-20T04:42:28Z

Title: Use of voltammetric methods for the analysis of trace metals in engine oils Authors: Tamrakar, P K; Pitre, K S Abstract: Accurate and convenient analytical procedures have been developed for the trace determination of metal ions in unused engine oil using advanced voltammetric methods viz. direct current polarography (DCP), differential pulse polarography (DPP) and differential pulse anodic stripping voltammetry (DPASY). The analysis has been carried out after ashing the samples and converting it to aqueous solution. Trace metals have been determined at different pH values in 0.1M (NH₄)₂ tartrate, 0.1M KCl and 0.01M EDTA as supporting electrolyte with 0.001% gelatin as a maximum suppressor. The results reveal that Cr, Pb, Cd, Zn, Co, Fe and Cu are present in the sample in significant amounts. The observed voltammetric results have been compared with those obtained using AAS. Statistical treatment of the observed voltammetric data reveal high accuracy and good precision of determination. Page(s): 843-846

Voltammetric determination of thallium(I) on a prussian blue/cinder paste electrode

2016-07-20T04:41:34Z

Title: Voltammetric determination of thallium(I) on a prussian blue/cinder paste electrode Authors: Zen, Jyh-Myng; Ho, Hsing; Chen, Pei-Yan Abstract: The effective utilization of industrially waste cinder for electroanalytical applications by trapping the hexacyanometallate (HCF) units from Fe³⁺, Ni²⁺, Co^3+, etc into the interlayer galleries of cinder has been reported. Prussian blue (PB ) is an Fe( III )-HCF with mixed valence and zeolite type properties. In the present investigation, the intercalation property of TI⁺ with PB/cinder paste electrode (designated as PBCPE) has been utilized for the analytical purpose. Basic cyclic voltammetric experiments with TI⁺ in 0.1 M KNO₃results in a continuous insertion of TI⁺ ions inside the PB gallery with the ejection of K⁺ ions. The insertion rate of TI⁺ ions in the PBCPE was much faster as compared to that in traditional PB modified electrodes. The PBCPE has also been utilized for sensitive determination of TI⁺ ions in real samples. Page(s): 839-842

Autopolymerization of pyrrole on the silver substrates roughened by an electrochemical method

2016-07-20T04:32:00Z

Title: Autopolymerization of pyrrole on the silver substrates roughened by an electrochemical method Authors: Liu, Yu-Chuan; Yang, Shung-Jim Abstract: Silver substrates have been roughened by a triangular-wave oxidati on-reducti on cycle (ORC) for 10 scans in an aqueous solution containing 0.1 N KCl. The AgCl₄ - complexes with grain sizes smaller than 100 nm are formed on the roughened Ag substrates. The pyrrole (Py) monomers are found to be autopolymerized on the roughened Ag substrates due to the electrochemical activity of the complexes. The polymerized polypyrrole (PPy) film has been confirmed by the characteristic bipolaron bands at ca 923 and 1203 cm^-1shown in the FTIR spectrum. Page(s): 836-838