K. V. Oskolok

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.

Total-reflection X-ray fluorescence study of electrochemical deposition of metals on a glass-ceramic carbon electrode surface☆

Abstract The features of electrochemical deposition and co-deposition of copper, cadmium and lead from aqueous solutions on disc glass-ceramic carbon (GCC) electrode surfaces were studied by total-reflection X-ray fluorescence analysis (TXRF). This method was found to be highly sensitive to the varieties of electrodeposit morphology and depth distribution of elements on the electrode surface. It allows identification of the mechanisms of metal nucleation and growth of thin film electrodeposits. The results of the TXRF study are in good agreement with the recent data of a number of spectroscopic and microscopic methods of solid surface analysis. The polished GCC was shown to be an excellent material for preparation of the sample carriers for TXRF analysis.

Formation of binary and ternary metal deposits on glass–ceramic carbon electrode surfaces: electron-probe X-ray microanalysis, total-reflection X-ray fluorescence analysis, X-ray photoelectron spectroscopy and scanning electron microscopy study

Abstract The features of the formation of binary and ternary alloys during the electrochemical deposition and co-deposition of copper, cadmium and lead from aqueous solutions on disc glass–ceramic carbon electrode surfaces were studied by electron-probe X-ray microanalysis, total-reflection X-ray fluorescence analysis, X-ray photoelectron spectroscopy and scanning electron microscopy. The macroscopic properties of electrodeposits such as morphology, lateral distribution of the elements along the disc electrode surface and depth distribution of the elements in the electrodeposit bulk were established. The mechanisms of metal nucleation and growth of thin films of electrodeposits were discussed.

X-ray fluorescence and atomic emission determination of cobalt in water using polyurethane foam sorbents

The conditions of analytical signal formation during direct X-ray fluorescence and arc atomic emission determination of metals using polyurethane foam sorbents were studied. A sorption spectroscopic technique of cobalt determination in water with preconcentration in the form of thiocyanate complexes based on simple ethers using polyurethane foam sorbents was developed. The linear calibration range was two orders of magnitude. With a cobalt concentration from 25 ml of water in the static mode, the lower limit of the metal content was 3 and 9 μg/l for X-ray fluorescence and atomic emission methods, respectively.

ANALYTICAL CAPABILITIES OF A MONOCHROMATIC MODEL OF X-RAY FLUORESCENCE EXCITATION BY INHOMOGENEOUS RADIATION FOR MULTI-ELEMENT SUBJECTS

New aspects of a monochromatic model of X-ray fluorescence excitation by bremsstrahlung and mixed X-ray tube radiation were examined in this paper. Analytic algorithms for calculation of the parameters of a virtual monochromatic source for complicated multicomponent subjects with different compositions and thicknesses were developed. Algorithm adequacy was tested during quantitative X-ray fluorescence analysis of metal alloys, slag, and ore concentrates.

Features of technogenic metal pollution of roadside soil according to x-ray fluorescence monitoring data

X-ray fluorescence monitoring of technogenic metal pollution of Moscow soil near two highways with heavy traffic was fulfilled. As a result of vehicles running, the macro and microelement composition of Moscow roadside soil was seen to substantially differ from the composition of both soddy podzolic soil (typical for Moscow region) and any other soil of the temperate climatic region of Russia. The average Fe, Mn and Ti contents in soil were found to exceed the usual background level by 2–5-fold, maximum Pb content — by 10–15-fold. The lateral and depth distribution of enumerated metal contents in soil near the highways was studied. It was shown that the behavior of lateral pollutant distribution in soil has no specific exponential shape. It has local extremuma and depends on the metal nature and the roadside terrain topography. For Pb — one of the most dangerous pollutants — the mechanism of chemical transformations and the interrelation of the pollutant chemical form, its molecular weight, the dwelling time in atmosphere and the distance to the highway were discussed.

Quantitative X-ray fluorescence analysis of multielemental subjects of complex shape without implementation of reference standards

A theoretical dependence of the ratio of intensities of X-ray fluorescence lines of chemical elements on the ratio of their concentration in a sample is suggested. The effect of various experimental factors on parameters of the obtained model is considered. A method of quantitative X-ray fluorescence analysis of multielemental subjects using the suggested calibration dependence without the implementation of reference standards is described. The adequacy and analytical advantages of the developed approach are demonstrated for the determination of the elemental composition of a sample of a metal alloy of complex shape.

Total-reflection X-ray fluorescence determination of cobalt and mercury in water using preconcentration on a polyurethane foam sorbent

A technique for X-ray fluorescence determination of cobalt and mercury in water using static and dynamic concentration in the form of thiocyanate and iodate complexes on polyurethane foam sorbents based on ethers is suggested. The possibility of the measurement of the X-ray fluorescence signal of analytes in the total external reflection mode, both in eluates and directly in the sorbent phase, is considered. The suggested approach allows one to improve the sensitivity of cobalt and mercury determination in water by 2–4 orders of magnitude in comparison with the classical sorption X-ray fluorescence techniques.

Direct X-ray fluorescence detection of mercury on polyurethane foam sorbents

An improved method for conducting a sorption X-ray fluorescence analysis of mercury (II) in water with static and dynamic preconcentrations in the form of iodide complexes on polyurethane foam sorbents based on ethers has been proposed. It was shown that optimizing the conditions of measuring analytical signals enabled a significant (one order of magnitude or more) increase in the sensitivity of the detection of X-ray fluorescence and widening of the linear range of graduation dependence.

The use of the ratios of intensities of spectral lines for X-ray fluorescence analysis of metal alloys and oxide materials

An X-ray fluorescence analysis technique is proposed, which is based on using ratios of intensities of spectral lines. The technique includes performing calculations for evaluation of calibration equations, which allows using few reference samples or carrying out standardless analysis, if necessary. That parameters of the calibration equations depend linearly on concentrations of disturbing elements allows one to simplify taking their influence into account. To apply the developed technique to analysis of samples containing a significant amount of undetectable light elements, a use of a dependence of intensity ratio of the characteristic radiation of the X-ray tube’s anode, coherently and incoherently scattered by a sample, on a total content of undetectable elements is proposed. The technique’s adequacy is demonstrated by analysis of standard steel samples, metal cuttings and iron-ore materials.