Vol 72, No 12 (2017)

A possibility of determining copper(II) after adsorption on polyacrylonitrile fiber filled with a KU-2 cation exchanger with immobilized 1-(2-pyridylazo)-2-naphthol (PANF–KU-2–PAN) is studied. The diffuse reflectance spectra of the carrier discs before and after the adsorption of copper in the batch mode are recorded. The dependences of the analytical signals of the copper complex on PANF–KU-2–PAN on adsorption conditions are studied. The conditions for determining 0.05–0.40 μg/mL of copper(II) by measuring diffuse reflection coefficient at 640 nm or visually by a color scale after the adsorption of copper from 20 mL of a solution containing 0.01 M of HCl are found. The determination of 0.1 μg/mL of copper does not interfered with equal amounts of Co, Zn, and Pb and double amounts of Ag, Fe(III), Cd, Mn(II), Bi(III), and Cr(III). The procedure is used for urine analysis. The following conditions of the preparation of urine samples for the determination of copper were selected: boiling with hydrogen peroxide followed by acidification to pH 2. A procedure for determining copper in urine with a limit of detection of 0.03 μg/mL was developed; the relative standard deviation does not exceed 25%; the duration of analysis of 5–6 samples is 30–35 min.

Presumable structures of polyethanolamines, synthesized by the catalytic β-hydroxyethylation of ammonia with an excess of ethylene oxide are determined by gas chromatography–electron ionization mass spectrometry and tandem mass spectrometry qualitatively, following fragmentation ways and also taking into account retention data. The preferable paths of consecutive reactions of the synthesis of polyethanolamines in a homologous series of isomers are found.

The selectivity of the separation of some anthocyanins on Diasphere-11-C10CN stationary phase (phase I) is compared with the traditional reversed Symmetry C18 phase (phase II). It is found that, in contrast to phase II, phase I is effective in the separation of isomeric pairs of anthocyanins of 6-hydroxycyanidin-3-rutinoside and delphinidin-3-rutinoside, 6-hydroxypelargonidin-3-rutinoside and cyanidin-3-rutinoside, which ensures the determination of anthocyanins of Alstroemeria flowers. A comparison of separation maps shows that, on phase I, as compared with phase II, retention does not decrease so much, when OH groups are added to the anthocyanidin structure; trend lines for 3-mono-, di-, and triglucosides have a higher slope, and the addition of a glucosidic substituent at position 5 results in a more significant decrease in the retention of anthocyanins. Different selectivity of the separation of anthocyanins on phase I makes this separation version a good alternative to traditional reversed phase chromatography.

The influence of proton-donor properties and concentration of dopant nanoparticles introduced into Nafion and MF-4SС perfluorosulfonic cation-exchange membranes on the characteristics of cross-sensitive DP-sensors (sensors whose analytical signal is the Donnan potential) in alkaline solutions of sulfur-containing organic compounds were studied. The dopants were acid salts of heteropoly acids (HPAs) and hydrated silica SiO₂ and zirconia ZrO₂ surface-modified with sulfur-containing groups and an acid HPA salt. A correlation was revealed between the DP-sensor sensitivity to anions (and zwitter-ions) in alkaline solutions, size and proton-donor ability of the added particles, and diffusion permeability of hybrid membranes. Optimum compositions of membranes for arrays of cross-sensitive DP-sensors ensuring the simultaneous determination of cations and anions (and zwitter-ions) in the test solutions with an error of less than 18% were selected.

Gas chromatography with mass spectrometric detection was used to analyze bitumens isolated from bottom sediments of peat lakes contaminated with petroleum products. Endogenous hydrocarbons are characterized by the presence of n-alkanes with an odd number of carbon atoms in the molecule in the characteristic region of C₂₃–C₃₃, the absence of a “hump” characteristic of oil products in the chromatogram, and the presence of light hydrocarbons, eluting in the initial part of the chromatogram (light hydrocarbons are usually lost when the sample is dried). The distribution profile of odd n-alkanes is used to assess the contribution of endogenous hydrocarbons to the “hydrocarbon index” with the help of the pattern recognition method. The concentration of light hydrocarbons is from 50 and 300–400 to 3500–5000 mg/kg for a number of samples and even up to 26000 mg/kg in some samples. The concentration of petroleum hydrocarbons and heteroatomic compounds varies from the lowest values of 30–80 mg/kg up to 20000 mg/kg and higher.