Vol 53, No 14 (2017)

A time-efficient protocol for quantification of methylphosphonic acid (MPA), a final hydrolysis product of nerve agents in aqueous environments, via liquid chromatography mass spectrometry is described. Chromatographic separation and mass spectrometry detection conditions are optimized to enable high sensitivity, selectivity, and accuracy of the approach and to eliminate impeding matrix effects associated with the analysis of water samples of natural origin. The developed technique is tested by analyzing the samples of natural waters that are spiked with a known quantity of MPA. With direct LC/MS/MS, the detection limit for MPA in natural waters is 10 ng/mL.

A review of the sample processing of different types of reusable metal-containing material (catalytic agents, e-wastes, cuttings, etc.) is given in the article; the purpose of the sample processing is the further analysis in the form of solutions: dilution in the mineral acid mix, alloying with different fluxes, leaching, etc. Increase in the temperature and pressure, ultrasonic impact, and microwave radiation are applied for the purpose of sample processing intensification. Methods of sample processing with application of sorbate concentration for the further definition of not only the noble, nonferrous, and rare metals but also the toxic elements are described. The review shows that the stage of sample processing is very important for achieving the potential of the applied analytical methods.

A rapid procedure is developed for determination of copper and zirconium in their binary alloys Cu_100–xZr_x in the content ranges corresponding to the region of bulk amorphization (x = 30–70) using inductively coupled plasma atomic emission spectroscopy (ICP-AES). The spectrometer operating conditions are optimized, and the analytical spectral lines (Cu II 224.700 nm and Zr II 354.262 nm) are selected, as well as calibration method and sampling procedure: dissolution in the mixture of HNO₃ and HF with addition of HCl, providing for the minimum standard deviation of the analytical signal. A procedure of oxygen determination by inert gas fusion technique and a procedure for determination of copper by spectrophotometry and zirconium by gravimetric analysis in a single sample together with quality control of ICP-AES are developed for the considered alloys. The results of analysis of Cu_100–xZr_x alloys according to the developed procedures agree well between themselves and accounting for adjustment of oxygen content agree within the error limits (not more than 0.5 wt %) with the added content of copper and zirconium upon synthesis.

A procedure for decomposing samples and determining rhodium in environmental objects by the catalytic method according to the reaction of sulfarsazen oxidation with periodate is proposed. The accuracy of the results is confirmed by determining rhodium using the method of inductively coupled plasma mass spectrometry. It is established that the rhodium content in the samples of road dust in Moscow is 0.01–0.04 g/t depending on the place of sampling. The standard deviation of repetition of the results of rhodium determination does not exceed 0.05.

A voltammetric study of the electrochemical behavior of red food azo dye Carmoisine on a glassy carbon electrode (GCE) is performed. The influence of various factors on the cathode signal of the dye is shown: pH and values of accumulation time and potential sweep rate. The operating conditions of Carmoisine identification in model media are selected: pH = 1.65, E_acc = –0.1 V, t_acc = 10 s, W = 100 mV/s. A linear dependence of the electrolytic reduction current of the dye on its concentration at –0.15 V is observed within 0.05–0.5 mg/L; detection limit of Carmoisine is 0.02 mg/L. A comparative determination of Carmoisine in soft drinks is performed by voltammetric and spectrophotometric methods.

A method of analysis of samples of spent petrochemical catalysts based on acidic decomposition of samples with further determination of platinum by inductively coupled plasma mass spectrometry is developed. The method allows analyzing various brands of catalysts, mixtures, and waste of catalysts formed during regeneration. A comparative study of the results of platinum determination obtained by different analytical methods in samples of several types of catalysts is performed. It is shown that spectrophotometric method of platinum determination in spent alumo-platinum catalysts recommended for certification of batches of catalysts and umpire analysis is not universal. At comparable accuracy indices, the analytical method should be selected taking into account the specific features of a particular batch of catalysts and restrictions of the applied method.

In determining a limited number of analytes in samples having a complex chemical composition with an unknown matrix, the combination of data mining algorithms (problems of clustering and regression) is proposed. This makes it possible to compensate for the influence of the components of the host medium on the intensity of the analytical line of an element being determined. The technology developed is tested in the X-ray fluorescence determination of S, Fe, Cu, Zn, and As in float concentrate samples during processing of polymetallic ores and V and Fe in synthetic film samples that are adequate in physicochemical properties to samples of welding fumes deposited on a filter. The error of the results of analysis has decreased by a factor 1.5–5 compared to the use of the Lucas-Tooth classical regression equation. The developed technology considerably increases the rapidity of analysis when it is used with X-ray spectrometers of consecutive action.

A semiempirical approach to the a priori evaluation of the effect of the surface relief on the results of X-ray spectral analysis of binary compounds is proposed. Dimensionless parameter k characterizing the effect of the relief on the intensity of intrinsic X-ray radiation is determined using the experimental data obtained for reference monocrystal specimens GaAs with known geometrical parameters of the relief.