Vol 74, No 11 (2019)

The use of hypercrosslinked polystyrene for the group sorption preconcentration of catecholamines is proposed. The conditions for the preconcentration of noradrenaline, adrenaline, and dopamine are optimized: a microcolumn (10 × 6 mm), mass of adsorbent 0.03 g, 25 mL of solution (pH ~ 8.5), and transmission rate of the solution 1.0 mL/min. Compounds were desorbed with 1 mL of 6 M acetic acid and determined in the eluate by reversed-phase HPLC with an amperometric detector (E = 0.8 V). Adsorption preconcentration ensures the reduction of the limits of detection for catecholamines by more than 20 times. The limits of detection were 0.7 ng/mL for dopamine and 1 ng/mL for noradrenaline and adrenaline. The procedure was applied to the analysis of model mixtures based on urine.

In this research, a fast, simple and highly efficient sample pretreatment technique based on air-assisted liquid–liquid microextraction (AALLME) followed by UV−Vis spectrophotometric detection has been applied for the preconcentration and determination of palladium in water samples. 1-(2-Pyridylazo)-2-naphthol (PAN) and chloroform were used as a chelating agent and extraction solvent, respectively. Parameters affecting AALLME, including pH of sample solution, concentration of PAN, volume of extraction solvent and number of extraction cycles were studied and optimized using Box–Behnken design. Under the optimum conditions, the calibration curve was linear in the concentration range of 5–700 ng/mL with the correlation coefficient (r²) of 0.996. Detection limit, enrichment factor, intra- and inter-day precision were 0.7 ng/mL, 193, 1.3 and 1.8%, respectively. Finally, the developed method was successfully applied for the determination of trace amounts of palladium in environmental water samples.

A procedure for the rapid simultaneous determination of anthraquinone and bisphenol A in paper and cardboard is proposed based on a combination of extraction with subcritical methanol and subsequent analysis of the extracts by HPLC‒tandem mass spectrometry. The achieved limits of detection are 25 and 250 µg/kg for anthraquinone and bisphenol A, respectively, and fully meet present-day safety requirements for pulp and paper products. The total duration of the analysis, including sample preparation, is not more than 45 min. The sensitivity of anthraquinone determination is 1‒2 orders of magnitude higher than that of the known procedures, including those with the preconcentration of analytes. The results obtained were successfully used to study paper and cardboard samples, in most of which unacceptably high levels of the anthraquinone concentration were found.

One of the main requirements for the methods of elemental analysis of unique archaeological samples is to minimize the damage they cause. Two new procedures for analyzing silver and gold samples, weighing several milligrams, obtained by drilling from the inner surface of silver and gold artifacts of the Borodino treasure, stored in the State Historical Museum, are described. The procedures are based on the autoclave decomposition of samples and subsequent analysis of the obtained solutions by inductively coupled plasma mass spectrometry(ICP–MS) and inductively coupled plasma atomic emission spectrometry (ICP–AES). They enable the determination of more than 60 impurity elements in each sample with a determination limits from 1 × 10^–2 to n × 10^–3 wt % for common elements (Na, Mg, Al, K, Ca, Ti, and Fe) and to n × 10^–7 wt % for REEs, Ir, Tl, and U. The correctness of the developed procedures is confirmed by the analysis of standard samples and by comparison with the ICP–MS results obtained with laser sampling, which allows direct analysis of samples without their dissolution.

Chromatographic methods of analysis of the products of the radical copolymerization of random copolymers of N-vinyl-2-pyrrolidone and 6-crotonoyl aminohexanoic acid are developed and molecular characteristics of the copolymers are determined. A method is proposed for the purification of the obtained carboxylated water-soluble copolymers of monomeric hydrophobic acid impurities by low-pressure gel-permeation chromatography.

We present a review of microextraction methods of separation and preconcentration, automated using the principles of equilibrium flow methods of analysis. The concepts and possibilities of automated methods of single-drop microextraction, dispersive microextraction, and homogeneous liquid–liquid extraction are discussed. The analytical potential of these methods is confirmed by some examples of analysis of food products and biological fluids.

General approaches to the automation of chemical analysis and radiochemical control in nuclear power engineering are discussed. For radioactive media with the highest specific activity, the necessity of the automation of the off-line control mode for minimizing the amount of the formed radioactive wastes is proved. Possibilities of the automation of the off-line analysis of primary coolants of nuclear power installations in the determination of chloride and sulfate ions are considered as an illustration. Based on a comparison with the results of analysis by ion chromatography, it is shown that the developed methods possess comparable analytical characteristics. A procedure for the determination of uranium using principles of cyclic injection analysis ensuring lower limits of detection in comparison with radiometric procedures is presented to illustrate possibilities of radiochemical analysis. The thesis about the advisability of transition to flow methods of analysis instead of batch methods used nowadays is substantiated.