Vol 71, No 11 (2016)

The review is devoted to one of currently most often used methods for the study of the elemental composition of samples differing by origin and matrix, laser sampling (LS), in combination with inductively coupled plasma mass spectrometry. The method ensures the analysis of samples without their transfer into solution and with high spatial resolution, up to several micrometers. The main restriction of laser sampling is due to elemental and isotopic fractionation, proceeding in the interaction of laser irradiance with the sample surface, on which photoelectronic and thermal processes, resulting in the formation of sample aerosols of different nature, can occur depending on the characteristics of laser irradiance. The paper covers works on the study of the effect of the laser wavelength, pulse duration, pulse fluence, plasma screening, explosive boiling, and the crater geometry on elemental fractionation and works in which fractionation coefficients were calculated on the basis of experimental data.

A new adsorbent is synthesized on the basis of silica consecutively modified by polyhexamethylene guanidine and 4,5-dihydroxy-1,3-benzenedisulfonic acid (Tiron) for the group preconcentration of Fe(III), Al(III), Cu(II), Pb(II), Zn(II), and Mn(II) followed by determination by inductively coupled plasma atomic emission spectrometry. The adsorbent in the batch mode quantitatively (recovery 98−99%) extracts Fe(III), Al(III) and Cu(II) ions at pH 4.0 and Fe(III), Al(III), Cu(II), Pb(II), Zn(II), and Mn(II) ions at pH 7.0; the time of attainment of an adsorption equilibrium does not exceed 10 min. Consecutive preconcentration at pH 4.0 and 7.0 in the batch and dynamic modes ensures the quantitative separation of Fe(III), Al(III), and Cu(II) from Pb(II), Zn(II), and Mn(II) and their separate determination. The quantitative desorption of metals was attained with 0.5−1.0 M HNO₃ (5 or 10 mL). In preconcentration from 200 mL of solution with 5 mL of a desorbing solution, the preconcentration coefficient was equal to 40. The developed procedure was used for the determination of metal ions in river waters of Krasnoyarsk Krai. The results obtained were verified by the added−found method.

The application of a piezosensor array to the assessment of the conditions of the digestive tract of birds by the presence and concentrations of dysbiosis markers in the equilibrium gas phase over the biosamples is discussed. A dysbiosis index is proposed for the rapid screening diagnosis of the dysbiosis status of intestines, calculated by the output data of the sensor array. The results obtained with chemical sensors are consistent with the data of microbiological studies. The method is very useful in monitoring the dynamics of variation of the dysbiosis index.

A method is proposed for the rapid identification of mineral waters by impedance spectroscopy combined with chemometric experimental data processing by projection to latent structures. Measurement conditions are optimized and performance characteristics are estimated. Possibilities of the extraction of qualitative and quantitative information on the concentrations of metal ions and anions in water, determination of the nature of mineral waters, degree of mineralization, and conformity to standard samples are shown.

A possibility of the determination of polyhexamethylene guanidine (PHMG) by voltammetry at an interface between two immiscible electrolyte solutions water–o-nitrophenyl ether is shown. An electrochemical sensor based on a microperforated polymer film is created to implement the method. Factors affecting the formation of the analytical signal were studied, working conditions of voltammetric measurements were selected on their basis. The developed method was applied to the determination of PHMG in antiseptics.

We present the results of determination of unsaturated fatty acids (FAs) in foods of animal origin. It is shown that, in addition to the main component, monounsaturated cis-9-octadecenoic (oleic) acid, other fatty acids may be present in the composition of lipids, depending on the type of raw materials used to prepare the food product. The determination of these acids can significantly vary depending on the presence of impurities and assay conditions. It is demonstrated that gas chromatographic systems with a flame ionization detector, conventionally used for the determination of the fatty acid composition, are useless for the reliable identification of close structural analogues of unsaturated essential fatty acids. The conditions of determination of these compounds with mass spectrometric detection are selected. The effect of the composition of analytes, which were animal ingredients, on the results is discussed. It is shown that the greatest difficulty is the determination of unsaturated fatty acids present in test samples of different aetiologies in amounts not exceeding 0.05–0.1%.

Components of the purple corn husk anthocyanin complex as a rich inedible source for the preparation of natural dyes were analyzed by reversed-phase HPLC with spectrophotometric and mass-spectrometric detection. The wide speciation of anthocyanins was found and its main components were identified as malonylation products of cyanidin-3-glucoside, 3″,5″-dimalonate (31.0%), 5″-monomalonate (32.2%), and 3″-monomalonate (7.3%), with low concentrations of similar pelargonidin and peonidin derivatives. The total accumulation level of anthocyanins in the samples under study exceeded 3.5 g per 100 g of an air-dry material. The results of the study of anthocyanin complexes of other purple corn parts are presented for comparison. Based on the studies performed, supplements to differential spectrophotometric and chromatographic methods for the determination of anthocyanins were proposed, which gave reproducible data for two alternative methods of their determination.