The Ionic Associate of Metamizole as an Electrode-Active Component of a PVC Plasticized Membrane Electrode

The technology for manufacturing a film membrane of the metamizole-selective electrode containing ion associate metamizole-octadecylammonium ODAH+MT− as an electrode active component (EAC) has been proposed. The main potentiometric characteristics of the metamizole-selective electrode have been determined. The expediency of the proposed design of the metamizole selective electrode for the determination of metamizole in dosage forms has been substantiated. The best composition of the membrane (wt.%) of the metamizole-selective electrode has corresponded to: ODAH+MT−—5.3; 2-nitrophenyloctylether—63.1; poly(vinyl chloride)—31.6. Electrode-active component in the membrane phase functions as an ion associate ODAH+MT−. Potentiometric characteristics of metamizole-selective electrode have been determined, which corresponded to: linear range 1 × 10−2–1 × 10−4 with limit of detection 4.58 × 10−5 M, electrode function slope −48.5 mV/dec., working interval pH 4.5–7.3, response time 60 s. The potentiometric coefficients of selectivity of the metamizole-selective electrode with respect to various ions have been determined. The possibility of determining metamizole in a medicinal product has been tested. The results of the analyses show good agreement between the two methods (relative error less than 7.0%) with coefficients of variation less than 5% for MT-SE and iodometric methods.

Determination of levamisole using ion-selective electrode

Current development of applied ionometry requires focusing of theoretical studies both on revealing the nature of the selectivity of electrode membranes and on the developing the new methods of membrane synthesis and their modification with the goal of obtaining more perfect structural units with improved functional properties. Elucidation of the relationship between the structural characteristics of the membranes and their effect on the electro-analytical properties is a rather important task. The interaction of organic cation levamisole with bromophenol blue was studied to meet the goals. Levamisole-selective sensor with a plasticized polyvinyl chloride (PVC) membrane has been developed. The electrode contains an ionic associate of levamisole with bromophenol blue. PVC was used as a matrix to model the membrane composition. Membranes plasticized with dibutyl phthalate (DBP), diethyl phthalate (DEP), dioctyl phthalate (DOP), dinonyl phthalate (DNP), dibutyl sebacate (DBP), tricresyl phosphate (TCP) were studied. It was shown that the nature of the plasticizer insignificantly affected the analytical characteristics of the electrode. The response is linear within the concentration range of 1 × 10–5 – 1 ×10–1 mole/liter with the slope of the electrode function 52.1 ± 1.0 mV/pC. The sensor has a quick response (10 sec) and can be used for at least 8 weeks without any divergence in the long run. The operation life of the membranes with a high plasticizer content is much longer. The electrode can be used within pH range of 3.0 – 8.0. Potentiometric selectivity coefficients of the electrode relative to a number of potentially interfering ions were determined. The developed electrode was tested in determination of levamisole in model solutions and pharmaceuticals («Decaris» and «Levamisole-Zdorovye»).

Visual test determination of trace amounts of germanium in the form of an ionic associate of 12-molybdogermanate with astrafloxin

Sorption-colorimetric and naked eye determination of germanium as ion associates of GeMo O 4– with triphenylmethane dyes is described. The sorption of the ionic associates (IA) of 12molybdogermanat with astrafloxin (AF) on filter paper was studied. The colored scales for naked eye detection and dependence of chromaticity coordinates from the germanium (IV) concentration were obtained. The methods were applied to the determination of germanium (IV) in coked coal, iron ore, and in waters in the concentration range from 4•10–8 to 1•10–6 mol•L–1. The developed test-systems for the determination of Germanium in natural and technological objects were tested in the course of training students of chemistry of Kryvyi Rih State Pedagogical University.

Potentiometric Sensor For Analgin Determination In Pharmaceutical Formulations

Ion associates (IA) of butylrodamine C with triiodide and iod bromide have been synthesized. Their thermal behavior is investigated. Thermolysis synthesized by IA BR+I3¯ passes through a number of intermediate stages, since the C4H9 radical, which is part of the dye, has a significant effect on the process of thermolysis of the ionic associate. IA BR+I3¯ begins to decompose significantly at a temperature higher than 140 єC with an endothermic effect at 240 єC and two small exothermic effects with a maximum at 282 єC and 355 єC (corresponding to the release of 2NH3, 8C2H4, 2HI). In the range of 380–720 єC, the exothermic effect of the IA combustion occurs at a temperature of 485 єC with significant mass loss. The obtained IAs are stable under normal conditions. An I3¯ and I2Br¯ sensor containing butyrodromine C associate of butylrodamine C with triiodide and iodum bromide was developed. The working interval of the pH of the triiodide sensor is 2 - 12, and for iodum bromide, the pH is 2 - 10, respectively. The linearity interval of the electrode function is in the range 9 ∙10-6 - 1 ∙10-1 mol L-1, the slope is 65 mV/pC for the triiodide, and for the iodine bromide - 1 ∙10-5 - 1 ∙10-1 mol L-1, the slope 68 mV/pC. The technique of potentiometric determination of analgin in medicines is developed.

Formation of ionic associates with pyrogallol complexes of antimony (III) and their application for spectrophotometric determination of antimony

The possibility of using water soluble pyrogallol red (PRWS) as a photometric reagent for the quantitative determination of antimony (III) in real objects has been studied. Formation of a colored product is observed in acidic solutions (pH 3.8 - 4.5) with a weak oxidizing agent (iodine) present for preliminary oxidation of SbHg to salts of Sb (III). The excess iodine is eliminated through introduction of sodium thiosulfate solution after obtaining the photometric form. The maximum analytical signal of the colored form is observed at 378 nm (e = 5.936 x 103). A decrease in the acidity of the solution (pH > 7) is accompanied by the formation of sodium salts of the reagent which prevents further complexation, whereas the only one maximum in the absorbance within the recommended pH range directly indicates to the formation of the the only one ionic associate (AI). The ionic associate thus formed appeared low stability in time. Unfortunately, change in the dielectric constant of the solution failed to give a positive effect and measurements of the absorbance of the colored compound were limited to 3 minutes. Determination of the composition and possible mechanism of the ionic associate formation was carried out on using the methods of molar ratios and isomolar series. After stripping of stibine into the absorption system, an ionic associate of the composition M:R = 1:1 is formed with a calculated stability constant of 4.01 x 105. The obtained results are used to develop a spectrophotometric (SP) method for antimony determination with the limits of detection and quantitative determination of the element 1.30 and 4.32 pg/ml, respectively. The developed method is valid in terms of the specificity, linearity, precision and accuracy, and, therefore, can be recommended for determination of the antimony content in any control and analytical laboratory.

DEVELOPMENT OF A POTENTIOMETRIC SENSOR SENSITIVE TO POLYSORBATE 20

Polyoxyethylated sorbitans (polysorbates) are widely used in the chemical, pharmaceutical, and cosmetic industries, but only quantitative determination is used mainly for chromatographic methods. In this paper, the results of the development and testing of a potentiometric sensor sensitive to nonionic surfactant polyoxyethylene sorbitan monolaurate (polysorbate-20) are presented. An anion of the heterogeneous acid of the Keggin structure (12-molybdophosphate heteropolyacid) was used as a counterion to obtain the electrode-active substance for the potentiometric sensor membrane. Polysorbate-20 does not form cations when dissociating in water and cannot directly interact with heteropolyanion; therefore, a cationic complex of polysorbate-20 with barium ions was previously prepared (similar to the interaction of metals with crown ethers). The resulting ion associate meets the basic requirement for the electrode-active substance of plasticized film polyvinyl chloride membranes of potentiometric sensors (poor water solubility and good solubility in organic solvents). Phthalic acid derivatives (dibutyl phthalate and dioctyl phthalate) were used as solvent-plasticizers for a polyvinyl chloride membrane. To determine the optimum conditions for the functioning of a potentiometric sensor sensitive to polysorbate-20, the influence of various factors on the electrode characteristics was studied. Quantitative content of the ionic associate in the polyvinyl chloride membrane, the nature of the membrane solvent-plasticizer, pH of a series of standard polysorbate-20 solutions) on the electrode characteristics of the plasticized membrane of the potentiometric sensor (sensitivity or slope of the electrode function, lower limit of linearity and minimum detectable concentration of polysorbate-20, which can be determined with the help of the developed potentiometric sensor) was studied. The optimal conditions for using the developed potentiometric sensor were found. The developed sensor allows for a short period of time (5–10 min) determining the quantitative content of polysorbate-20 in industrial products at the level 10–5–10‑6 mol/l. The potentiometric sensor sensitive to polysorbate-20 can be used for the development of a potentiometric method for determining the clinical reception of polysorbate-20 in various types of industrial products.

Spectrophotometric determination of trace amounts of iodide-ions in form of ionic associate with brilliant green using electrochemical oxidation

A combined method involving electrochemical oxidation of iodide to iodate at a platinum electrode followed by extraction in CCl4 of ionic associates of iodine-iodide complexes with brilliant green, formed in excess of iodide, was developed for the spectrophotometric quantification of iodide. The slope of the calibration curve yields a molar extinction coefficient of ɛ = 3·105 L mol−1cm−1. This method can be used for the quantification of iodide in the concentration range of 3·10−7 − 3·10−6 mol L−1 with a detection limit of 5·10−8 mol L−1. The interfering effect of other ions on the determination of the iodide concentration was also investigated. The method was successfully applied for the determination of iodide in real samples of NaCl and spring water. Relative standard deviation is 1–2%.