SU1437766A1 - Composition of membrane of ion-selective electrode for determining the activity ofammonium ions in pure solutions - Google Patents

Abstract

The invention relates to the field of ionometry, namely the development of new membranes of ion-selective electrodes. The aim of the invention is to reduce the detection limit of ammonium cations. For this purpose, a new elective strut has been proposed.

Description

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This invention relates to analytical chemistry and can be used as a sensor in automatic analyzers to monitor the concentration of ammonia in wastewater and ammonia in liquid media.

The purpose of the invention is to reduce the detection limit of ammonium ions.

Crown ether with fragments of D-tartaric acid - (1S, 2S) -1,2-dihydroxy-13-benzyl-4,7,10,16,19,22-hexaox-13-aza-cyclotricose and which has a structural formula

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To reduce the response time and improve the electrode function, tetrafenylborate lithium salt is introduced into the membrane.

Example. The proposed membrane composition is prepared as follows. 0.160 g of polyvinyl chloride is dissolved; in 0.330 g of bis (1-butyl-nonyl) -adipi: nate with stirring until a homogeneous mixture is formed within 5 days, 5 mg of crown-ether and 5 mg of lithium tetraphenylborate are added to the mixture dissolved in 6 ml of tetrahydrofuran and stirred at a temperature below 50 ° C until complete dissolution of the polyvinyl chloride. The resulting solution was poured into a Petri dish with a diameter of 50 mm. After evaporation of tetrahydrofuran (2 days) in air, an elastic film 0.5 mm thick is obtained. Cut diameters of a certain diameter (0.8 cm) from the film are glued to the end of the PVC tube. The finished electrode is filled with O, 1 mol / L NH4C1 solution and soaked in tehe14377662

, per day in 0.1 mol / l solution, after which the electrode is ready for use.

When working with dilute solutions, measurements were performed in closed cells containing the measured solution. In this case, the stability of the electrode potential is observed.

Q at LOW OTCS concentrations (10 -5 mol / l).

The composition of the membrane prepared in this way allows one to make measurements of the concentration of ammdium ions in the range (6.5 ± 0.5) - Yu mol / l, the pH of the analyzed solution is 2-7.0.

In tab. 1 shows the electroanalytical parameters of the proposed membrane composition.

In tab. 2 shows the selectivity coefficients of the developed electrodes.

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Claims (1)

Invention Formula The composition of the membrane of the ion-selective electrode for determining the activity of ammonium ions in pure solutions, containing electro-active substance, polyvinyl chloride, and plasticizer, characterized in that, in order to reduce the detection limit, it contains as an electrode-active substance (IS, 2S) -1, 2-dihydroxy-1Z-benzyl-4,7,10,16,19,22-hexaox-13-azacyclotriosan, as a plasticizer - bis (1-butylnonyl) -adipinate and additionally tetraphenylborate lithium at the following content of the components of the membrane, May.%: (1S, 28) -1,2-dihydroxy-13-benzyl-4, 7,10,16,19,22-hexaox-13-azacyclotricosanum 0.50-5.40 Tetraphenylborate lithium 0.35-3.80 Polyvinyl chloride 30.0-33.0 Bis- (1-butyl-nonyl) -adipate Others at low concentrations otcs (10 -5 mol / l). The composition of the membrane prepared in this way allows one to make measurements of the concentration of ammdium ions in the range (6.5 ± 0.5) - Yu mol / l, the pH of the analyzed solution is 2-7.0. In tab. 1 shows the electroanalytical parameters of the proposed membrane composition. In tab. 2 shows the selectivity coefficients of the developed electrodes. Invention Formula The composition of the membrane of the ion-selective electrode for determining the activity of ammonium ions in pure solutions, containing electro-active substance, polyvinyl chloride, and plasticizer, characterized in that, in order to reduce the detection limit, it contains as an electrode-active substance (IS, 2S) -1, 2-dihydroxy-1Z-benzyl-4,7,10,16,19,22-hexaox-13-azacyclotriosan, as a plasticizer - bis (1-butylnonyl) -adipinate and additionally tetraphenylborate lithium at the following content of the components of the membrane, May.%: (1S, 28) -1,2-dihydroxy-13-benzyl-4, 7,10,16,19,22-hexaox-13-azacyclotricosanum 0.50-5.40 Tetraphenylborate lithium 0.35-3.80 Polyvinyl chloride 30.0-33.0 Bis- (1-butyl-nonyl) -adipate Others 1437766 Electrode characteristics of the proposed membrane composition Table (6.5fO, 5) -10 - 58tO, 8 The selectivity coefficients of the proposed composition membranes Cation L + I Rb I 1 Ba Sr Ca | Kij 0,009 0,012 0,100 0,075 0,088 0,002 0,001 0,002 0,0005 0.5-5 2-7.0 table 2 Mg +