CS264873B1 - Membrane for barium ion selective electrode - Google Patents

Abstract

A membrane for a barium ion-selective electrode with improved application properties, formed by a film of a polymeric material, such as polyvinyl chloride, plasticized with o-nitrophenyl-n-octyl ether, o-nitrophenyl-n-dodecyl ether or 2,4-dinitrophenyl-n-octyl ether, in which a complex barium salt of the schematic formula L2-Ba.(TPB)2 is dissolved, where Ba is a barium cation, TPB is a lipophilic tetraphenylborate anion and L is a ligand, a neutral carrier, substituted 3,6,9-trioxaundecanedioic acid diamide, specifically N,Ν'-diphenyl-Ν,Ν'-di-(2-n-propyloxycarbonylphenyl) 3,6,9-trioxaundecanedioic acid diamide.

Description

The invention relates to a membrane for a barium ion-selective electrode, more precisely to a neutral carrier which forms a ligand in a complex barium salt which is the actual active component of the ion exchanger in the membrane.

The barium electrode is one of the newer types of ion-selective electrodes, recently appearing in the literature and on the market. The preparation of neutral carriers based on substituted diamides of oligoglycolic acids, or substituted diamides of substituted oligoglycolic acids and complex barium salts with them, and membranes for this electrode were studied by Simon and his colleagues (e.g. Guggi, M.; Pretsch, E.; Simon, W.: Anal. Chim. Acta 1977, 91, 107, Laubli, M. W.; Dinten, 0.; Pretsch, E.; Simon, W.: Anal. Chem. 1985, 57, 2756). They used high-molecular polyvinyl chloride as the polymer matrix for the plastic membranes, and o-nitrophenyl-n-octyl ether as the solvent of the complex salts and at the same time as the PVC plasticizer.

Membranes according to Czechoslovak Patent No. 217 537 are also described, where lipophilic tetraaryl borate anions are used as anions for complex salts, Czechoslovak Patent No. 224 919, where N,N'-diphenyl-N,N'-di-(2-ethoxycarbonylphenyl)diamide of 3,6,9-trioxaundecanedioic acid is used as a ligand, and Czechoslovak Patent No. 240 059, where N,Ν'-diphenyl-Ν,Ν ¹ -di-(2-naphthyl)diamides of 3,6,9-trioxaundecanedioic acid are used as a ligand.

Improved selective properties against important, frequently occurring interferents, sodium and calcium ions, are exhibited by the membrane for the barium ion-selective electrode according to the invention, formed by a solution of a new barium complex salt in nitrated arylalkyl ethers, fixed in a suitable polymer matrix, e.g. high molecular weight polyvinyl chloride, characterized in that the ligand L of the complex salt of the schematic formula <L ₂ . Ba) (TPB) ₂ is N,N'-diphenyl-N,N'-di-(2-n-propyloxycarbonylphenyl)diamide of 3,6,9-trioxaundecanedioic acid, of the structural formula

Ba is a barium cation and TPB is a lipophilic tetraphenylborate anion.

The properties of the prepared and used membranes are demonstrated in the examples given.

Example 1

A membrane for a barium ion-selective electrode was prepared by a conventional method, by casting from a cyclohexanone solution, containing a complex barium salt of the schematic formula L ₂ . Ba . (TPB) ₂ , where L is a ligand according to the invention, i.e. N,N'-diphenyl-Ν,Ν'-di-(2-n-propyloxycarbonylphenyl) diamide of 3,6,9-trioxaundecandioic acid, Ba is a barium cation and TPB is a lipophilic tetraphenylborate anion. The complex salt is dissolved in o-nitrophenyl-n-octyl ether and the high molecular weight polyvinyl chloride Mevil III is softened with the solution. The membrane with a thickness of 0.2 mm has the following composition: Lj . Ba . (TPB) ₂ 1.43 wt. %, o-nitrophenyl-n-octyl ether 60.00 wt. % and Mevil III 38.57 wt. %.

An electrode with an internal reference electrolyte BaCl,, c = 0.1 — 1 mol.l and an internal reference electrode Ag/AgCl was made from the membrane. The electrode was measured in a cell with a saturated calomel electrode. The measurements were carried out in aqueous solutions at a temperature of 293 -2 K.

The electrode response to the activity of barium ions was measured in BaCl2 solutions in the concentration range of 10 to 10 mol.l. The measurement results are given in Table X.

BaCl ₂ , σ = a-6

10'

Table I (mol. I ^-1 )

Cell EMF (mV)

-91.3 -64.3 -36.9 - 9.9 + 14.7 +38.2

and under the same conditions the selectivity coefficients were measured the use of chloride solutions of the respective cations Pot in the form of log K _n . in tabulation II. tía, j Table II c = 0.1 mol. I ^-1 j = ^To B^j j = ^log Cj Li ⁺ -3.49 nhJ -3.32 On ⁺ -3.22 Mg ²⁺ -5.23 To ⁺ -2.94 Ca2 ⁺ -3.39 Rb ⁺ -2.89 Sr ²⁺ -1.12 Cs ⁺ -2.86

Example 2

Similarly to example 1, a membrane was prepared with the same complex salt L ₂ . Ba .

. (TPB) ₂ and o-nitrophenyl-n-dodecyl ether was used as a PVC plasticizer. The membrane had the following composition: L ₂ . Ba . (TPB) ₂ 1.43 wt. S, o-nitrophenyl-n-dodecyl ether 60.00 wt. % and Mevil III 38.57 wt. i. As in example 1, an electrode was made from it and its

properties. Response to activity tivity in Table IV. of barium ions is given in Table III and the selectivity coefficients Table XII BaC^z c « (mol. I ^-1 ) EMS cell (mV) 10- ⁶ -89.5 10~ ⁵ -65.9 10' ⁴ -38.4 10 ³ -11.3 io ^-2 +13.3 10 ¹ +36.5 Table IV 3 = ^log Cj j » ^lo * ^K Ba*j Li ⁺ -4.44 nhJ -3.60 On ⁺ -3.30 Mg ²⁺ -5.32 To ⁺ -2.86 Ca2 ⁺ -3.39 Rb ⁺ -2.63 Sr ²⁺ -1.19 Cs ⁺ -2.71

As in Example 1, a membrane was made, where 2,4-dinitrophenyl-n-octyl ether was used as a plasticizer. The membrane had the following composition: L ₂ . Ba . (TPB) ₂ 1.43 wt. %, 2,4-dinitrophenyl-n-octyl ether 60.00 wt. % and Mevil III 38.57 wt. %. As in Example 1, an electrode was made from it and its properties were measured. The response to the activity of barium ions is given in Table V and the selectivity coefficients in Table VI.

Table V

BaCl ₂ , c - (mol. I ¹ ) EMS article (mV) 10 ⁶ -88.7 10 ⁵ -61.7 IO ^-4 -33.7 10 ^-3 - 7.0 10 ^-2 +16.9 10 ^-1 + 40.2 Table VI 3 = - "Pot ^{log K} Ba,j j = ^To ^j Li ⁺ -3.49 nh£ -3.26 On ⁺ -3.24 Mg ²⁺ -6.12 To ⁺ -2.91 Ca ² + -3.02 Rb ⁺ -2.86 Sr ²⁺ -0.76 Cs ⁺ -2.97 P P R E C T I O N INVENTION

Membrane for a barium ion-selective electrode formed by a foil of a suitable polymer

Claims (1)

Barium ion selective electrode membrane formed by a foil of a suitable polymeric material, for example high molecular weight polyvinyl chloride with an ion exchanger based on the complex barium salt of the schematic formula (L ₂ Ba) (TPB) ₂ where L is a ligand, neutral carrier, Ba is a barium cation Lipophilic tetrafenylboronic acid anion, characterized in that N, N'-diphenyl-N, N'-di (2-n-propyloxycarbonylphenyl) 3,6,9-trioxaundecanedioic acid diadimide of structural formula L is used as ligand L