V. M. Ivanov

Sorption of noble-metal ions on silica with chemically bonded nitrogen-containing ligands

A study has been made of the sorption of Ir(IV), Rh(III), Pt(IV), Ru(IV), Os(VIII), Pd(II) and Au(III) from aqueous solutions by silica chemically modified with nitrogen-containing organic ligands, as a function of hydrochloric acid concentration, time of contact, concentration of the element and the ionic strength. Sorption of noble-metal ions at pH > 1 on a sorbent containing monoamine groups seems to be due to a complexation mechanism, and to an anion-exchange mechanism at pH < 1. With aminopropyl-silica 1000-fold concentration of Ir(IV) and Rh(III) from their 10(-8)-10(-7)M solutions was achieved and these metals were subsequently determined on the sorbent surface by X-ray fluorescence. Detection limits were 10-20 ng/ml. There was no interference from 1000-fold quantities of non-ferrous metal ions and Fe(III). With the sorbent containing bonded diethylenetriamine groups, 1000-fold concentration of Au(III) was achieved, and it was then determined on the sorbent surface by an atomic-emission method. Conditions for desorption of Au(III) with pyridine and potassium thiocyanate were developed.

Stability of ascorbic acid in aqueous and aqueous-organic solutions for quantitative determination

The stability of ascorbic acid is studied in dependence on the pH of its aqueous solution. It is shown that itenhances in acidic and weakly alkaline media and upon the addition of acetonitrile. The stabilizing effect of ethanol is considerably lower. Processes occurring in aqueous and aqueous-organic solutions of ascorbic acid are considered and the results obtained are explained. These data are important for the development of analytical procedures and can be used in the chemical and pharmaceutical industries for improving the stability of preparations containing ascorbic acid.

Determination of epoxide and hydroxyl groups in epoxide resins by IR spectrometry

The IR spectra of 40% acetone solutions of epoxy resins with different molecular mass were studied. A correlation was found between the intensities of some absorption bands for the determination of epoxide (920 cm–1) and hydroxyl (3450 cm–1) groups and for the estimations of the average molecular mass of the resin (1108 cm–1).

Test methods for extra-laboratory analysis

This article reviews the basic requirements for test methods used for chemical analysis outside the laboratory, classifying them according to several criteria, such as the nature of the processes generating the analytical signal, chemical principles and applications. Also covered are enzymes. Test methods and tools for liquid samples are reviewed, as are systems for measurement and recording results. Finally, there is an overview of applications.

Liquid chromatography of palladium and non-ferrous metal chelates with 1-(2-pyridylazo)-2-naphthol

1-(2-Pyridylazo)-2-naphthol has been used for extraction concentration of palladium, copper, cobalt and nickel from aqueous solutions and subsequent separation of the chelates obtained, by means of high-pressure liquid chromatography. A technique for determining microamounts of palladium in aqueous solutions in the presence of 100-fold ratio of copper and 80-fold ratio of cobalt has been developed.

3,4,5-Trihydroxyfluorones As Analytical Reagents

Acid-base, spectrophotometric, and chromaticity characteristics of 3,4,5-trihydroxy-9-(2′-sulfophenyl)-6-isoxanthone (Pyrogallol Red, PR) and its 2,7-dibromo derivative (Dibromopyrogallol Red, BPR) were considered. The effect of the ionic strength, solvents, and surfactants on these characteristics was discussed. The complexation of the reagents with metal ions in the presence of second and third components (surfactants of different natures and organic reagents) was considered. The analytical characteristics of two-, three-, and four-component complexes were compared. The selectivity of the reagents, methods for changing the selectivity, and applications in analytical chemistry were considered. It was noted that chromaticity measurements are promising for studying the complexation of ions and their determination.

Determination of Rare-Earth Elements in Sulfide Minerals by Inductively Coupled Plasma Mass Spectrometry with Ion-Exchange Preconcentration

A procedure was developed for determining ultratrace rare-earth elements in sulfide minerals by inductively coupled plasma mass spectrometry with ion-exchange preconcentration. The concentration factor was 200. The found concentrations of rare-earth elements were 6–30 times lower than those in chondrites. For lanthanum and praseodymium, RSD < 10%; for other rare-earth elements, RSD < 6%. The accuracy of the results was verified by the addition of known amounts of Eu, Tb, Tm, and Lu to a chalcopyrite sample at the stage of decomposition with HCl and HNO3. The calculated yield of rare-earth elements was 94–96%. The detection limit was from 0.06 ng/g (6 × 10–9%) for lutetium to 5 ng/g (5 × 10–7%) for cerium. The procedure was used for the determination of rare-earth elements in chalcopyrites, pyrites, and sphalerites.

Capabilities and prospects of the development of a chromaticity method in analytical chemistry

Published data on the application of the chromaticity method in analytical chemistry in the past 15 years are systematized and analyzed. Attention is focused on the analytical aspects of the chromaticity method; its capabilities, prospects for its use in analytical chemistry, and new versions of analytical signal measurements are considered.

40 years since the discovery of the arsenazo III reagent

The review was devoted to progress in the application of the well-known and widely used reagent Arsenazo III in analytical chemistry. Arsenazo III 2,7-bis[(2-arsonophenyl)azo]-1,8-dihydroxy-3,6-naphthalenedisulfonic acid was synthesized by S.B. Savvin in 1959

Acid-base, spectrophotometric, and colorimetric properties of 1,2-dihydroxyantraquinonone-3-sulfoacid (Alizarin Red S)

Acid-base, spectrophotometric, and colorimetric properties of 1,2-dihydroxyantraquinonone-3-sulfoacid (Alizarin Red S, ARS) have been studied in aqueous solutions at pH 3–13. Equations of calibration curves have been obtained for the dependences of absorbance and colorimetric functions (CF) on the ARS concentration. Molar absorption coefficients and CF have been determined. Dissociation constants of ARS have been determined using a spectrophotometric technique in its computational and graphical versions at an ionic strength from 0.1 to 0.5.