No abstract available

[en] To decrease the detection limit of scandium and increase selectivity of amperometric determination, oxidation of 2-furylacryloyl-N-p-chlorophenylhydroxylamine (FACPhHA) and 3-styrylacryloyl-N-phenylhydroxylamine (SAPhHA) on a graphite electrode has been studied by volt-amperometry. The possibility has been established of using the oxidation current of the reagent for plotting the titration curves. The solubility of scandium complexes with FACPhHA and SAPhHA under conditions of titration against the background with pH 6.0 has been determined and equals (2.1+-0.3)x10^-6 and (5.3+-0.3)x10^-7, respectively. The methods have been developed of amperometric determination of scandium with the use of the considered reagents against backgrounds with pH 5.5-6.5. The use of SAPhHA has decreased the limit of scandium detection down to 0.1 mgk/ml. Besides, the amperometric method makes it possible to titrate in turbid and coloured media what is an advantage of this method. The developed method is used for determination of scandium in scandium silicide

[en] The voltammetric study has been made of oxidation of a new organic reagent N-cinamoyl-n-tolylhydroxylamine (CTHA) at a graphite electrode. The possibility has been established of using the current of oxidizing CTHA for titration end point indication up to pH 8. Procedures have been developed of amperometric titration of small amounts of scandium and yttrium by using CTHA. The solubility of the complexes formed has been determined. Scandium has been determined in the presence of some foreign elements. It has been shown that lanthanum, niobium, and praseodymium do not interfere with the scandium determination by CTHA at a ratio of 1:10 and yttrium at a ratio of 1:4

[en] Voltammetric curves have obtained of electrical deposition and reduction of N-thiobenzoyl-N-p-tolylthydroxylamine (TBTHA) at graphite and mercury dropping electrodes over a wide range of the supporting electrolyte acidity. The anodic current of oxidizing TBTHA and the cathodic current of its reducing may be used for amperometric titration. A procedure is suggested of determining molybdenum(VI) by using a graphite microelectrode in the presence of some elements. To remove the effect of iron(III), nitriletrimethylphosphonic acid is used

No abstract available

[en] Study of the DTPA voltamperometric behaviour has been carried out using a graphite electrode, and optimum conditions of amperometric titration of yttrium and lanthanum in optic glasses, artificial mixtures and alloys have been established. Composition of complexes of metals with DTPA answers the ratio of Me:DTPA=1:1 under the optimum conditions. Magnitudes of calculated logarithms of stability constants constitute 22.2+-0.48 for yttrium and 19.8+-0.52 for tantalum. The possibility of determination of gallium and yttrium at their combined presence by successive titration has been established

[en] The review of the works starting from the middle 50-ties on the use of new organic reagents of hydroxamic acid class in analytical chemistry is presented. The fact that N-arylsubstituted derivatives of hydroxamic acids form low-soluble chelates with ions of different elements at different acidity is of special value. It permits to determine many elements, as well as rare ones, in multicomponent systems. N-benzoyl-N-phenyl-hydroxylamine and its analogous are successfully used in different electrochemical methods of analysis: extraction polarography, potentiometry, ionometry. Using the given reagents in electrochemical methods Zr, Sc, Nb, Ce, Mo, V, Th, La, In, Y can be determined. The application of hydroxamic acids in non-electrochemical methods of analysis is considered

[en] Method of amperometric determination of gadolinium, including titration of solution investigated by complexing agent - N-m-nitrocinnamoxylphenylhydroxylamine is suggested. Fibration of analyzed solution is performed by means of standard reagent solution in ethanol. Buffer solutions with pH 6.3-7.5 at 0.7 V potential of graphite rotating microelectrode (s. c. e.) were used as the background. The given method enables to determine 1-100 μg/ml of gadolinium. The relative standard deviation doesn't exceed 2% at the number of parallel determinations equal 5. The following elements with ratios by weight (Gd:El):K, Na(1:10000); Ca, Ba (1:300); Mg (1:500); Al (1:60); Fe(3) (1:3); Pb(2) (2:1); Cr(3) (2:1); Y (2:1); La (2:1); Eu (3:1); Dy (2:1); Pr (1:1); Tb (2:1) don't prevent determination of gadolinium

[en] N-m-nitrocinnamoylphenylhydroxylamine - a new reagent of a group of unsaturated hydroxamic acids has been synthesized; pK-7.7 -0.03. It has been shown that the reagent is oxidized electrochemically on a rotating graphite microelectrode. The reagent reacts with lanthanum to form a slightly soluble compound with a metal: reagent ratio of 1:3 at pH 7.1. The compound solubility under conditions for titration 9x10^-6 M. The real detection limit for lanthanum (3) is 9x10^-6 M. The possibility has been shown of amperometric determination of lanthanum in luminophors with the composition of Lasub(2)BaOsub(x)Ssub(y)xEu(3-5%)

[en] Possibility of using organic reagent of unsaturated N-arylsubstituted derivatives class of hydroxamic acids N-m-nitrocinnamoyl phenylhydroxylamire (NCPHA) for amperometric titration of yttrium using indication of e.t.p. by current of reagent oxidation on graphite electrode is investigated. Metal and the NCPHA form difficultly soluble complex with ratio of yttrium to the NCPHA, which is equal to 1:3. Buffer mixtures of 0.1MNH₃+0.1MCH₃COOH composis tion with pH 6.3-7.5 are optimal background solutions for amperometric titration of yttrium. The proposed method permits to determine 10-600 μkg of yttrium in the volume of 10 ml. Effect of the series of strange elements on titration of yttrium with NCPHA (Ca, Mg, Mn (2), Al, CU (2), Fe (3) REE and others) is studied. The developed method is used for yttrium determination in luminophores of Casub(n)-- Ysub(m)Fsub(z)xMn(2) (1-10%) composition