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Based on the screening of some heavy metals (HMs) content in the humus soil horizon of the Transcarpathian region, the regularities of the distribution of HMs in the soils of different landscape zones have been established. It is shown that increasing of the terrain height, the content of HMs in soils decreases (except for Mn and Hg) and for the total HMs content the values of the Spearman correlation coefficient are: Cu – (-0.84); Zn – (-0.83); Mn 0.77; Mo – (-0.91); Co – (-0.82); Pb – (-0.83); Hg – absent; for the content of acid-soluble forms: Cu – absent; Zn – (-0.72); Mn 0.75; Mo – (-0.89); Co – (-0.86); Pb – (-0.77); Hg is absent. This pattern is associated with the tectonic and geological features of the different landscape zones. The calculation of the migration coefficient (the ratio of the content of acid-soluble forms to the gross content) has been shown that in mountainous regions this indicator has the highest value for Zn, Pb, and Cu. That means the potential danger of migration of these heavy me­tals and their bioavailability. This is probably connected to the type of soil in the mountai­nous areas of the region. A pronounced inter-element correlation of the HMs content in soils (except for Hg) has been established and the corresponding values of Pearson’s coefficients for the gross content are: Cu:Zn – 0,96; Cu:Mn – (-0,84); Cu:Mo – 0,89; Cu:Co – 0,99; Cu:Pb – 0,87; Zn:Mn – (-0,79); Zn:Mo – 0,91; Zn:Co – 0,96; Zn:Pb – 0,86; Mn:Mo – (-0,86); Mn:Co – (-0,84); Mn:Pb – (-0,75); Mo:Co – 0,87; Mo:Pb – 0,81; Co:Pb – 0,87. This makes it possible to predict the content of several HMs in the soils of the Transcarpathian region based on the results of determining one of them. In general, the content of HMs in the humus soil horizon (total content and content of mobile forms) is lower than the corresponding values of maximum permissible concentrations.

C1–C5 aldehydes are toxic substances formed by chemical transformation of organic compounds into the atmosphere. Actual methods used to analyze aldehydes in environmental samples are usually slow and complex, whereas there is a need for rapid and frequent monitoring. Here, a simple, fast method for the spectrophotometric determination of the total content of aldehydes in waters has been developed. The method is based on the spectrophotometric determination at 478 nm of hydrazones in an alkaline medium, generating the hydrazon-α-oxiazinic tautomeric forms, which are formed by condensation of aldehydes and 3,5-dinitrobenzhydrazide (3,5-DHBA). We optimized the conditions of the condensation reaction, e.g., 0.05–1.0 mol L−1 H2SO4, heating at 95 °C for 10 min, and the procedure of the spectrophotometric determination of the total aldehyde content at pH higher than 11 and λmax of 478 nm. Those conditions allow the determination of the total aldehyde content in the presence of various interferences, e.g., most ketones including acetone, 2000-fold of anions: HCO3−, CH3COO−, SO42−, Cl−, F− and cations: Li+, Na+, K+, Mg2+, Ca2+, Sr2+. The calibration curve was linear in the range of 0.087–13.5 mg L−1 for aldehydes, with R2 of 0.99; the limit of detection was 27 μg L−1 (0.9 μmol L−1) and the limit of determination was 87 μg L−1 (3.2 μmol L−1) in terms of formaldehyde. The suggested procedure was successfully applied for the determination of the total aldehyde content in rainwaters and model mixtures with recovery of 97.8–102.7%. The accuracy of the procedure was confirmed by an analysis with a reference method.

Consumption of edible plants satisfies a significant part of human body needs in macro- and micronutrients while biologically active substances contain strong antioxidant properties and reduce the risk of a number of diseases. Balanced nutrition and design of personalized diets and treatment rely on the data on the content of macro- and micronutrients and biologically active substances. We determined polyphenol and anthocyanin content in 22 species of local edible plants using modified spectrophotometric method with Folin-Ciocalteu reagent as well as chemical elements' content in a mixture of edible plants from 13 regions using standard procedures. We performed correlational analysis of the obtained data and analysis of the main components in OriginLab, developed regional models of chemical elements' content for a mixture of edible plants, and conducted cluster analysis using common tools in Python. The results of biologically active substances' study demonstrated that the highest content of polyphenolic compounds and anthocyanins was found in grape meal of Vitis vinifera L. The study of chemical elements' content demonstrated that edible plants from lowland areas are the best and revealed clear dependences of the elements on each other and geographical conditions. The analysis of the principal components confirmed this finding. Based on the obtained data, a number of regional models of chemical elements' content in a mixture of edible plants were built, tested, and evaluated. Obtained results are the basis for designing various diets, filling composite databases of the region's food, and creating the newest biologics-pharmabiotics.

Background For Transcarpathian region, with a pronounced landscape diversity of territories and significant areas of nature reserves, well water is an important source of drinking water. Screening of the microelement composition of drinking well water in Transcarpathia has not been carried out before. The microelement composition of such well water can be considered as the natural (baseline) indicator of quality. Methods We screened of the microelement (Cu, Zn, Fe, P, Ca, Mg, Mn, Mo, Co, As, Se, I, Br and F) composition of drinking well water in Transcarpathian region (for all 13 districts). Standard methods were used to determination the concentration of chemical elements in well water: electrothermal atomic absorption spectroscopy (Cu, Zn, Fe, Mn, Mo, Co), flame photometry (Ca, Mg), inverse voltammetry (total iodine), potentiometry (F, Br), fluorimetric (Se) and spectrophotometric methods (P, As). Results The content of chemical elements in well water varies over a wide range, in particular for Cu: 3.27–11.6 μg⋅L−1, Zn: 8.16–38.2 μg⋅L−1; Fe: 37.9–411 μg⋅L−1; P: 51.4–193 μg⋅L−1; Ca: 85–139 mg⋅L−1, Mg: 10.2–18.9 mg⋅L−1, Mn: 22.8–78.1 μg⋅L−1; Mo: 2.33–8.96 μg⋅L−1; Co: 1.72–3.38 μg⋅L−1; As: 2.9–17.4 μg⋅L−1; Se: 0.95–3.6 μg⋅L−1; I: 0.94–4.4 μg⋅L−1; Br: 712–3098 μg⋅L−1; F: 71–149 μg⋅L−1. The tendency that the content of microelements (Cu, Zn, Mn, Mo, Co, As, Se, I, Br, and F) in well waters of different landscape zones was evaluated through Spearman's coefficients. The content of trace elements in the waters of different landscape zones increases in the series: lowland landscape > foothill landscape > mountainous landscape (Spearman's coefficients: Cu – 0.62, Zn – 0.85, Mn – 0.69, Mo – 0.83, Co – 0.79, P – 0.74, As – 0.72, Se – 0.75, I – 0.80, Br – 0.91, F – 0.73). Conclusion It is shown that the chemical composition of well water can be considered as the natural (baseline) indicator of quality of groundwater in Transcarpathia, taking into account topographic and geochemical features of the territories. Among the main problems of drinking well water in Transcarpathia are the relatively high content of Fe (typical for different landscape zones), as well as the low content of Se, I and F. The correlation of inter-elements content of chemical elements in drinking well waters of Transcarpathia has been revealed. The most pronounced correlations are observed for such pairs of microelements: Co–Mo (r > 0.95), I–Br (r > 0.92), Zn–Br (r > 0.89), Cu–Co (r > 0.84), Se–Co (r > 0.84), Mo–P (r > 0.84), Mo–I (r > 0.82) and Zn–Mo (r > 0.80)., Water quality; Well waters; Microelements composition; Geochemical features; Pearson's and Spearman's correlation coefficients; Landscape diversity; Analytical chemistry; Environmental analysis; Environmental chemistry; Environmental geochemistry; Geochemistry; Environmental science.

The present study is dedicated to development of improved method for determination of trace amounts of fluorides in natural waters which is based on the interaction of fluorides with ion associate (IA) of Al(III), salicylic aldehyde acylhydrazones (benzhydrazone (SABH) and 4-picolinhydrazone (SAPH)) and polymethine dye Astra Phloxine FF (AP). Comparison of analytical forms [Al(SABH)2]⋅AP and [Al(SAPH)2]⋅AP showed that the analytical system Al(III)-SAPH-AP is more effective, namely, a higher level of preconcentration of the analytical form is ensured by and extraction equilibrium is achieved faster. Based on the study, we propose a new, fast, simple, reliable, sensitive, and accurate method of the indirect UV–Vis-spectrophotometric determination of fluorides grounded on the interaction of fluorides with IA of Al(III), SAPH and AP with the utilization of vortex-assisted liquid-liquid microextraction (VALLME). The method is based on the discoloration of the microextract of IA of Al(III), SAPH and AP (Al-SAPH-AP) in presence of fluoride ions due to the formation of fluoride complexes of aluminum with higher stability. The effect of various factors has been studied. The optimal conditions of the UV–Vis-spectrophotometric determination of fluorides were defined as: pH 7.0–10.0, 1.0⋅10−6 mol⋅L−1 Al(III); 4.0⋅10−5 mol⋅L−1 SAPH; 1.0⋅10−6 mol⋅L−1 AP; λ = 560 nm. VALLME have been carried out in 250 μL of CCl4 at 20:1 vol ratios of aqueous and organic phases, with vortexing at 3000 rpm for 15 s followed by centrifugation at 2000 rpm for 2 min. The determination of fluorides is feasible in the presence of various interferences. The calibration curve shows the linear dependence in the range of 0.3–114 μg⋅L−1 of the fluorides concentration (R2 = 0.993) with the limit of detection of 0.086 μg⋅L−1 and the limit of determination of 0.284 μg⋅L−1. The accuracy of the proposed protocol of fluorides determination was verified towards a reference method on the samples of natural rivers waters (RSD 2.6–3.1%, recovery 98.3–101.4%).

The procedure for determining Hg, Cd, Pb, Zn, Cu elements in fresh water based on the preconcentration of these metals as complexes using poly-3-pyridyl-5-thioxo-4-allyl-4,5-dihydro-1H-1,2,3-triazole-1-carbodithionic acid with further measurement of atomic adsorption are proposed. The detection limits for metals are 5, 8, 20, 5 and 20 ng/dm3 respectively.

The article investigated the impact of sodium salts of acylhydrazones of pyroracemic acid as modifiers of the matrix on the electrothermal atomic-absorption determination of aluminum. The technique has been developed for determination of aluminum in fresh waters with the detection limit 0.005 m/dm3.

The formation of ion pairs of Rh(III) and Ir(III) with pyruvic acid acylhydrazones and symmetric cyanine dyes, derivatives of 1,3,3-trimethyl-3H-indolium, was studied. It was demonstrated that rhodium and iridium could be determined by the extraction-photometric technique in synthetic mixtures in the presence of each other.