CS217537B1 - Membrane for barium ion selective electrode - Google Patents

Abstract

Membrane for a barium ion-selective electrode, consisting of polyvinyl chloride, a plasticizer from the group of nitrated aromatic alkyl ethers and an active complex of the schematic formula L».Ba.(X)2, where L is a ligand, e.g. bis-diphenylamide of tetraglycolic acid, Ba is barium and X is an anion, which is the tetraphenylborate anion or its derivatives.

Description

The invention relates to a membrane for a barium ion-selective electrode, or rather to a complex forming its active component.

One of the newest types of ion-selective electrodes that have recently appeared in the literature is barium ion-selective electrodes. The preparation of this type of electrodes has recently been studied by Simon and co-workers. As a complexing ligand for these agents, he used bis-diphenylamine of tetraglycolic acid, dissolved in o-nitrophenyl-n-octyl ether. The mentioned components were used together with polyvinyl chloride as membranes for barium ion-selective electrodes, the composition of the active complex corresponding to the schematic formula,

L.Ba.(SCN) ₂ , where

L is tetraglycolic acid bis-diphenylamide ligand,

Ba is barium,

SCN is a sulfocyanide anion.

We have found that the same or somewhat improved properties are exhibited by membranes for a barium ion-selective electrode according to the invention, containing a complex ligand, forming a complex of the schematic composition

L ₂ -Ba-(X) ₂ , where

L is a ligand, for example, tetraglycolic acid bis-diphenylamide,

Ba is barium and

X is an anion, the essence of which lies in the fact that the tetraphenylborate anion or its derivatives are used as the anion X.

Example

The above complex L ₂ .Ba.(X) ₂ , where X was the tetraphenylborate anion according to the invention, was part of membranes with the composition:

complex according to the invention 1.36 wt. %.

polyvinyl chloride 30.62% by weight.

'2,4-dinitrophenyl-n-octyl ether 68.02% by weight.

Electrodes with an internal solution of 0.1 U barium chloride and an internal reference electrode of Ag/AgCl were made from membranes of this composition. Measurements were carried out using a cell consisting of a barium ion-selective electrode with a membrane according to the invention and a calomel electrode.

The attached tables show the behavior of this electrode, in Table I in pure barium chloride solutions and in Table II in barium chloride solutions with an adjusted ionic strength to 0.3 with a lithium chloride solution.

and I [mol/l] Bb ²⁺ ems [mV] 10 ⁶ -78.7 IO* -60.3 10 ⁴ -33.7 10 ³ - 6.5 IO” ² +19.8 10 ¹ +41.0

Δ emf [mV]

18.4

26.6

27.2

27.2

21.3

Table 11 c [mol/l] Ba ²⁺ ems [mV]

Δ emf [mV]

IO ⁶ -100.4 IO ³ - 79.9 10' ⁴ - 50.9 IO' ³ - 22.5 IO' ² + 6.4 10'' + 34.5

20.5

29.0

28.4

28.9

28.1

The above electrodes were also measured for logarithms of selectivity coefficients by the separated solutions method. Their values are given in Table III.

Table of lilies

log ^to Ba,Li = -3.23 log ^to Ba,NH ₄ ~ “ ^2.8 ° log ^to Ba,Na = -2.58 log ^to Ba,Mg = ⁵ >°° log ^to Ba,K = -2.25 log ^to Ba,Ca ^{= 2} ' ⁷ ° log ^to Ba,Rb = -2.21 log ^k Ba,Sr = ⁰ ' ⁸⁷ log ^to Ba,Cs = -2.36

Example 2

A similar complex Lg.Ba.(XJg), where X was the tetra-p-chlorophenylborate anion, was part of the membrane with a composition of the complex according to the invention of 1.36 56 wt.

polyvinyl chloride 30.62% by weight.

2,4-Dinitrophenyl-n-octyl ether

68.02% by weight

Ion-selective electrodes were made from these membranes as in Example 1 and the same measurements were performed on them, the results of which are shown in Tables IV, V and VI, i.e. the measurement results for standard chloride solutions in Table IV, the measurement results for barium chloride solutions with ionic strength adjusted with lithium chloride in Table V and the logarithms of selectivity coefficients in Table VI.

Table IV

Table

Table

[mol/l] Ba ²⁺ ems fmV] Aems [mVj ,o- ⁶ -80.9 19.9 ,0-5 -61.0 27.6 10' ⁴ -33.4 27.3 IQ' ³ - 6.1 26.5 10" ² +20.4 2«,4 "0" ¹ +41.8 in [mol/l] Ba ²⁺ ems [mV] Δems [mVj 10" ⁶ -99.4 ,0-5 -78.5 20.9 ,0 ^-4 -50.1 28.4 ,o- ³ -2, ,4 28.7 10~ ² + 7,’ 28.5 28.2 10 ^_1 +35.3 VI ^{108 to} Ba,Li ' - ³ > ³⁰ log ^to Ba,NH ₄ ⁼ “2' ^{96 l0} « ^k Ba,Na ^{= 2} > ⁵⁵ log ^to Ba,Mg =- ⁴ ' ^{96 108 k} Ba,K ' ² > ²⁹ log ^for Ba,Ca ^{= 2} > ^{73 108 k} Ba,Rb ⁼ -2' ²⁵ log ^to Ba,Sr =-°· ⁹⁰

^l0 « ^k Ba,Cs ⁼ - ² > ³⁷

Claims (1)

A barium ion selective electrode membrane comprising a complex ligand forming a complex of the schematic formula .Ba L _2. (X) 2, where L is ligeind, for example the bis-acid diphenylamide tetraglykolové, barium Ba, and X is an anion, characterized in that the anion X is used tetrafenylboritanového complex or derivatives thereof.