N. F. Kushchevskaya

Micellar extraction concentration of microcomponents by phases of nonionic SAS at the cloud point

Main principles of the micellar extraction concentration of microcomponents from aqueous solutions by phases of nonionic SAS at the cloud point have been studied, and the data available in literature dealing with the use of micellar extraction for concentrating and separating ions of metals, organic compounds, and biologically active substances have been classified.

Standardized and unified methods for determining phenols in natural and drinking waters and main trends of their development

This paper presents MAC (maximum admissable concentration) values of phenol and its derivatives in natural and drinking waters specified in the normative documents of Ukraine, Russia, the USA, Canada, Great Britain, and international organizations WHO and EU, and also provides data on standardized and unified methods for determining phenols at the MAC level. This paper has discussed directions of the development of techniques for determining phenols during the last fifteen years that are based on preliminary extractive or sorptive concentration and subsequent detection using photometric, gas chromatographic, fluorometric, and kinetic techniques of analysis, and also the high performance liquid chromatographic (HPLC) method with electrochemical and flame ionization detection.

The impact of water-soluble humic acids on extraction-photometric determination of anionic SAS with methylene blue in natural waters

The estimation of possible applications of the standard extraction-photometric method for determining anionic SAS by using methylene blue has been performed during the analysis of dyed natural waters. It is shown that humic acids significantly affect the adequate determination of anionic SAS by the specified method. The ways of eliminating the harmful influence of humic acids during the analysis of natural objects are also proposed.

Methods of determining perchlorates

The literature sources on the methods of determination of perchlorate in different objects has been systematized. Perchlorate in waters and soil is a microcomponent and for its determination highly sensitive methods are required. Known spectrophotometric methods are characterized by sensitivity at the level 10–100 μg/dm3. A higher sensitivity (5 μg/dm3) is achieved by the ionochromatographic method, however, due to the interfering effect of impurities the use of other methods is necessary, for instance, the mass spectrometric one. A shortcoming of the latter is labor input and a high cost of the equipment. The paper has substantiated the necessity of perfecting the methods of determining perchlorates with an increase of sensitivity, selectivity, accessibility, and cost reduction.

Electrothermal atomic-absorption determination of lead and cadmium with preliminary micellar extraction

The article investigated micellar extraction of lead and cadmium by the phases of nonionic surface-active substance Triton X-100 in the presence of pyridylazo reagents. It is shown that complete joint removal of metals into the micellar phase is observed within pH interval 9–11 when using hydrophobic 1-(2-pyridylazo)-2-naphthol. Optimized are conditions of electrothermal atomization of lead and cadmium in the micellar phase. A technique was proposed of atomic-absorption determination of metals in waters with preliminary micellar-extraction concentration at cloud temperature.

Binding of anionic surface-active substances by water soluble humic acids

The interaction of anionic SAS with water-soluble humic substances has been studied. The quantitative characteristics of this interaction (binding constants) were calculated and the impact of various factors on the specified interaction was estimated. The binding of anionic SAS by humic substances was found to depend on the contact duration, ambient temperature, concentration, the nature, and size of molecules of humic substances, and also on the nature and length of the hydrocarbon radical of ASAS molecules.

Determination of anionic surface-active substances in waters

We have studied sorption on the SDB-L polymer sorbent of anionic surface-active substances (ASAS) of the alkylsulfate class with a different length of a hydrocarbon radical and alkylarylsulfonates (sulfanol), methylene blue in the presence and absence of ASAS. We have developed the technique of sorption-photometric determination of the latter in waters with determination limit, which depends on ASAS hydrophobicity and constituting for C10-0.046, C12, C16-0.020–0.024, and sulfanol-0.010 mg/dm3 at the sample volume 25 cm3.

Determination of perchlorate in aqueous extracts of soils by photometric and chemiluminescent methods

We have developed the techniques for determination of perchlorate in soil extracts by chemiluminescent and photometric methods based on the formation of an ionic pair by cuproinate Cu(I) with perchlorate. The detection limit—respectively 0.1 and 0.3 mg/kg of the soil.

Fluorimetric determination of inorganic selenium in waters with the use of anion-exchange sorbents

We have investigated a possibility of sorption concentration concurrently with fractionation of different valence forms of inorganic selenium during fluorimetric determination of its mass concentration in natural and drinking waters. We have also studied sorption of anions of tetra- and hexavalent selenium from the aqueous medium on the surface of anion-exchange sorbents. We have found optimal conditions of sorption and desorption of selenate- and selenite-anions on the strong-base anion-exchanger AV-17.

Extraction-free determination of small amounts of perchlorate in waters

We have investigated determination of trace amounts of perchlorate and proposed the techniques for water analysis and its content. The determination was carried out in the form of an ionic associate with cetyltrimethyl ammonium after sorption of the white deposition on a stained paper filter and variations of diffusion reflection and also in the form of an ionic associate with rhodamine 6G after its sorption of the filter with the change the chemiluminescence intensity occurring after addition of the reagents CoCl2, H2O2, and NaHCO3. For preliminary concentrating and separation of perchlorate from interfering impurities standard modified sorbents were used. The detection limit of perchlorate constitutes respectively 20 and 0.4 μg/dm3.