Vol 78, No 3 (2023)

The review summarizes the results of publications on methods for determining arsenic in metallurgical materials from 2000 to 2022

A method is proposed for the analysis of trace element concentrates by a thin layer method in combination with inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation (LA). Trace elements concentrates were evaporated on preliminarily prepared areas of a high-purity silicon substrate, after which an LA-ICP-MS analysis was performed. The influence of the LA parameters and the conditions for recording the spectra on the signal of the analytes and the substrate material was studied. The analytical capabilities of the thin layer method in combination with LA-ICP-MS for the analysis of high-purity substances with the preconcentration of trace elements were evaluated. Using an analysis of high-purity nitric acid as an example, it was shown that the limits of detection for analytes in the LA-ICP-MS analysis of trace element concentrates using the thin layer method are in the range from n × 10–11 to n × 10–8 wt %. Thus, the development of combined procedures of analysis, including the preconcentration of trace elements and an analysis of concentrates by LA-ICP-MS, makes it possible to reduce the limits of detection for most analytes by one order of magnitude compared to instrumental ICP-MS analysis.

A possibility of using a monitor calibrator for the determination of luminescent compounds is shown on an example of quinine. The determination is based on the irradiation of a sample with broadband radiation in the visible and near UV spectral regions from a built-in source exciting phosphor molecules and the simultaneous registration of the radiation incident on the detector. Measurement conditions are selected. Quinine can be determined in the range of 60−750 µM, the limit of detection is 20 µM. The determination is not affected by common inorganic ions, as well as sweeteners and acidity regulators present in many beverages. The developed method of determination is applicable to the analysis of carbonated drinks and drugs. Compared to a traditional spectrofluorimeter, monitor calibrator is characterized by compactness, mobility, ability of detecting luminescence in cuvettes of various sizes and shapes, and lower cost.

The conditions for the formation of physically adsorbed three-layer coatings of quartz capillary walls in capillary electrophoresis (CE) with successively deposited oppositely charged layers of polydiallyldimethylammonium chloride (PDADMAC) modifiers and citrate-stabilized gold nanoparticles (GNPs) are proposed. It was shown that three-layer PDADMAC–GNP–PDADMAC coatings favorably differ from monolayer coatings with PDADMAC by greater stability in a wide range of pH (2–10). The formed coatings were characterized by scanning electron microscopy, and the presence of a uniform dense layer of nanoparticles on the capillary surface was confirmed. The applicability of the modified capillaries under CE conditions was demonstrated by the separation of a mixture of 16 carboxylic acids. An increase in the separation selectivity achieved with the use of three-layer coatings based on GNPs was explained by the reversible exchange of citrate anions on the GNP surface with negatively charged analytes in the course of electrophoretic analysis.

6-Nitro-7-(4'-nitrophenyl)-5-ethyl-4,7-dihydropyrazolo[1,5-a]pyrimidine-3-carboxylate (1) is one of promising antitumor compounds exhibiting biological activity against type 2 casein kinase, which is currently considered as a promising target in chemotherapy. Using the method of cyclic voltammetry, it was shown that the electrochemical activity of compound 1 in a mixed solution of Tris-HCl and ethanol (1 : 1) at pH 7.5 on a glassy-carbon electrode is due to the electrochemical reduction of the nitro group conjugated with the phenyl ring. A method was developed for the determination of compound 1 by direct cathodic square-wave voltammetry. The linearity region of the corresponding calibration curve obtained in a solution of a mixture of Tris-HCl and ethanol (1 : 1) at pH 7.5 is 5–500 mg/L (R2 = 0.988), the limit of detection is 0.8 mg/L, the limit of quantification is 2.4 mg/L. The accuracy of the developed procedure is close to 100%, the relative standard deviation is 1.4%.

This work is a continuation of a study on the use of chemical gas sensors and a portable “electronic nose” for diagnosing obesity and related pathologies in children in a hospital. Using a portable Bio-8 device, 330 volatile skin compound profiles were measured in the forearm region on an empty stomach in various states of children with various diseases during inpatient examinations and treatment in the endocrinology department. Monitoring changes in the profile of volatile skin compounds during the period of hospital stay in obese children made it possible to identify priority metabolic disorders in multiple pathological disorders and diagnoses by a characteristic set of chemical biomerkers of processes, reliably detected in skin secretions on the right forearm. Multiparametric data of the “electronic nose” were processed by principal component analysis to assess ranking of the results into the groups “Normal” and “Obesity with a risk of the development of type 2 diabetes mellitus (DM)”. Based on the highly informative parameters of the sensor array, changes in the chemical composition of the skin gas profile on the right forearm during the period of patients’ stay in the hospital and the effectiveness of standard approaches in each specific case were evaluated, and the personalization of treatment was thus increased. Simple calculated parameters and a method for assessing lipid and carbohydrate metabolism disorders based on the signals of eight sensors above the skin measured for 200 s without sampling were proposed. The sensitivity of the method for monitoring changes in the metabolome in a hospital is at least 80%. Specificity for lipid metabolism disorders is 100%; for type 1 diabetes, 100%; and for mixed pathologies varies from 70 to 85%.