[en] A method has been developed of cerimetric determination of niobium in the presence of molybdenum which is based on pre-separation of niobium by its hydroxide precipitation followed by dissolution in a mixture of KOH and H₂O₂. For a 1:1 mixture of Nb₂O₅ and MoO₃ a standard relative deviation is 0.002

[en] Conditions of the formation and extraction of basic dyes associates with complex acids of Mo(6) with catechol derivatives (tetrabrominecatechol-TBC and tetrachlorocatechol-TCC) are studied. The optimum reaction conditions are found. On the basis of experiments the extraction-photometric method for determination of Mo with TBC and brilliant green in a standard water sample is developed. Bi, Sb, Ti Sn hamperiOg the analysis were removed by coprecipitation on Fe(3) hydroxide. Iron traces remaining in the solution were masked by ascorbic acid. The extraction was realized by carbon tetrachloride

[en] Photometric methods for determination of zirconium, niobium and tantalum in bla algae. Algae ash has been subjected to analysis. Zirconium has been determined by formation of colored complex with arsenazo 3, niobium - by reaction with orthonitrophenylfluoron. Separation from interfering elements has been performed by coprecipitation on Fe(OH)₃ and subsequent extraction by chloroform solution of tribenzylamine. Tantalum has been separated by extraction of its fluoride complex from sulphate fluoride medium by the mixture of acetone with isobutanol in presence of ammonium sulfate. Tantalum has been determined in the form of sahcylfluoron in presence of ammonium oxalate Zr content in the algae ash by order corresponds to its content in the plankton ash

No abstract available

[en] The authors create a titrimetric method of determining niobium in the presence of tantalum. The proposed method permits the determination of niobium in various objects: niobium(V) oxide, technical niobium hydroxide, and columbite concentrate, at various ratios of niobium and tantalum. The data obtained are cited in tables and it can be seen that at the selected ratios of niobium and tantalum in the sample, niobium is virtually entirely determined. Tantalum(IV), vanadium(V), molybdenum(VI), and tungsten(VI) interfere with the determination of niobium

[en] Titanium methods of niobium and scandium (yttrium) determination from different sample weight amounts in corresponding double oxide systems Nb₂O₅-Y₂O₃(Sc₂O₃) are presented. The recommended combination of cerimetric (Ce(SO₄)₂-titrant, ferroin-indicator) and complexometric (using ammonia and EDTA solutions) determination of niobium and scandium (yttrium) respectively permits to simplify and to accelerate analytic control of oxide material quality

[en] A study was made on extraction of ion associates of niobium complex acids with pyrocatechol(R)derivatives and basic dyes(D). The best results were obtained when using tetrabromopyrocatechol and brilliant green. It is shown that the degree of associate extraction depends on medium acidity and anion background; optimal conditions: 0.2-0.9 M H₂SO₄ and 0.25-1.35 M HCl. 10-fold D excess and not less than 100-fold R excess are required for complete Nb binding in associate. Component ratio in formed associate is Nb:R:D=1:2:2. Ta prevents spectrophotometric Nb determination under optimal conditions. If acidity is increased up to 1.8-2.0 M HCl, Nb can be determined in the presence of 7-fold Ta excess and in the presence of 100-fold amounts of Zn, B, Al, Ga, In, Tl, Ge, Sn, Zr, Hf, Sb, Mo, W but comparable Ti amounts prevent this. The developed technique can be used for determining 1-10 μg Nb in high-pure substances

[en] Works on analytical chemistry of tantalum published in 1970-1988 have been systematized and generalized. Attention is concentrated on the recent achievements in the field of chemical, physicochemical and physical (including neutron-activation) methods of tantalum determination. Spectrophotometric and atomic-emission methods of tantalum determination, especially in the presence of niobium, have been considered in greater detail

[en] A new titrimetric method for determining niobium macroquantities in different natural and industrial objects in the presence of ten-fold tantalum excess is suggested. Titanium (4), vanadium(5), molybdenum(6), tungsten(6) interfere with the niobium determination

[en] Reactions between niobium or tantalum and salicylfluorone were studied in the presence of cationic, non-ionic and anionic surfactants. Tartrate, fluoride and sulfate initial solutions of niobium and tantalum were used. It was shown that niobium salicylfluoronate had a high molar absorptivity (>1.5x10⁵) in tartrate and sulfate solutions in the presence of cationic surfactants. The possibility was shown of determining 0.1-1.0 μg Nb in the presence of 5 μg Ta in sulfate solutions