The paper considers the possibility of determining the total content of tin in various forms of presence in the waters of the Azov and Black Seas, which differ in salinity. Organotin compounds, when present in waters, interfere with the determination of inorganic forms of tin by direct injection by ICP spectrometry. It is shown that before determining the total content of tin in various forms of presence in waters with organotin compounds, microwave mineralization of the analyzed samples is required, under which a quantitative conversion to the inorganic form of tin is ensured. The highest efficiency of decomposition of water samples was achieved using oxidizing mixtures based on nitric acid (5.0 см3 HNO3; 4.0 см3 HNO3 + 1.0 см3 HCl и 3.0 см3 HNO3 + 2.0 см3 H2О2). Limits for the determination of tin (LOQSn) in solutions prepared in deionized and model sea waters with different salinities have been established. According to the proposed scheme of analysis for ICP-AES, the LOQSn values in water samples from the Azov and Black Seas were 0.40 and 0.47 µg/dm3, respectively, with direct injection of the sample. In the ICP-MS determination of LOQSn also increases with increasing water salinity and ranges from 0.03 (deionized water) to 0.45 μg/dm3 (model sea water with a salinity of 18 ‰). The developed scheme of analysis made it possible to determine the total content of tin, considering all forms of its presence in sea waters. Satisfactory convergence of the results of analyzes after microwave mineralization of waters is observed for ICP-AES determination of the total tin content in the range from 0.45 to 10.0 μg/dm3, and for ICP-MS in the range from 0.40 to 5.00 μg/dm3. In the analyzed water samples of the Azov and Black Seas, the total tin content was found to be 0.20 and 0.23 µg/dm3, respectively.

The current study discussed the capabilities and limitations of tin direct determination in the waters of the Black and Azov Seas using the ICP-MS and ICP-AES methods without the separation and concentration of the analyte. The conditions for the analysis of waters, the influence of dilution and matrix components on the results of the analysis were established. As the salinity of the seawater increased, the slope of the calibration curve decreased, regardless of the detection method used. The leveling of the matrix effect of seawater on the analytical signal of tin was achieved by diluting the sample up to 100 times. A significant decrease in the analytical signal of tin was observed on the samples of seawater characterized by the high salinity. These methods allowed determining tin at the concentrations ranging from 0.33 μg/dm3 (ICP-MS), 0.37 μg/dm3 (ICP-AES) to 5 μg/dm3 in natural (fresh) water or seawater with low salinity level according to the calibration curve of the deionized water. For ICP-MS and ICP-AES determination of tin in seawater with the salinity level above 6‰ and tin concentration of more than 5 μg/dm3, it was required to use the calibration dependence constructed on the model seawater considering the salinity of the object. The studies have shown that the content of tin in the Kuban River is 0.13 μg/dm3. In the Sea of Azov, the concentration of tin in the water, depending on the sampling site, was less than 0.33 μg/dm3 (Taman) and 1.8 μg/dm3 (Temryuk, commercial port). In the Black Sea, the concentration of tin in the seawater samples from Novorossiysk city was higher and ranged from 0.55 μg/dm3 (embankment) to 1.5 μg/dm3 (seaport) and 2.1 μg/dm3 (grain terminal).

The current paper considers the possibility of determining the total tin content in the waters of the Azov and Black seas using the hydride generation technique. The conditions for the generation of tin hydrides were optimized for the subsequent determination by inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). When studying the matrix effect of the components, it was found that the transition metals Ni2+, Co2+, Cu2+, and Fe3+ reduce the analytical signal of tin. The possibility of leveling the influence of transition metals by various binding masking agents (L-cysteine, EDTA, tartaric acid, potassium iodide and thiocarbamide), of which L-cysteine showed the greatest efficiency, was studied. Under the optimized analysis conditions, the limits for the determination of inorganic tin in the model waters were established, which, regardless of the salinity level, were 0.05 and 0.03 μg/dm3 for ICP-AES and ICP-MS, respectively. The possibility of determining tin in waters using the hydride generation technique, when the analyte was present in the form of organotin compounds, was evaluated. It has been shown that for the ICP spectrometric determination of the analyte with the generation of hydrides in water containing organotin compounds, microwave mineralization of the samples was required. The satisfactory convergence of the analyses’ results was observed when determining the total content of tin in sea waters in the concentration ranges of 0.05–2.00 and 0.03–2.00 μg/dm3 for ICP-AES and ICP-MS, respectively. The developed methods were used to determine tin in the waters of the Azov and Black seas; the total analyte content in them was 0.15 and 0.23 μg/dm3­, respectively.

In the current paper, the possibility of separating inorganic and organic forms of tin occurrences has been considered and the features of determining the total content of organotin compounds (OTC) in waters with different salinities by ICP-spectrometry with hydride generation were studied. Various approaches to the separation of the chemical forms of tin by liquid-liquid extraction with various solvents, as well as by precipitation with fluorides, iodides, aqueous solutions of ammonia and iron (III) chloride at analyte concentrations at the MPC level for fishery reservoirs, have been examined. The separation of the chemical forms of tin due to the taking out the OTC by liquid-liquid extraction turned out to be inefficient because of the incomplete extraction of analytes and partial extraction (up to 15%) of the inorganic form of tin into the organic phase. Precipitation of inorganic and organic forms of tin using fluorides, iodides, ammonia, and iron (III) chloride also turned out to be inefficient. This was due to the low content of analytes, at which their quantitative precipitation was difficult. Under the conditions of high-level mineralization of sea waters, it was also unlikely that a competing reaction of changing the chloride environment to fluoride or iodide one would occur. Separation of the chemical forms of tin was achieved using the solid phase sorption. The Diapak C18 silica gel sorbent selectively extracted the organic form of tin from waters with different salinity under the optimized conditions. The optimized conditions for separating the chemical forms of tin made it possible to develop a method for determining the total content of OTC in natural waters with different salinity from the difference between the total content of the analyte and the inorganic form of tin. To determine the total content of the analyte, microwave mineralization of the water sample was carried out; the concentration of the inorganic form of tin was determined after its solid-phase separation from organotin compounds. The lower limits of analyte concentrations determined were 0.03 and 0.05 μg/dm3 for the ICP-MS and ICP-AES methods, respectively, which made it possible to separately determine the OTC during the ecoanalytical monitoring at the level below the MPC.