JPH0453379B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ion selective electrode membrane. More specifically, the polymer electrode membrane of the present invention only contains a special plasticizer and a fat-soluble anion, and does not contain a special ion carrier. It has the characteristic of exhibiting a selective electromotive force response to ions. The present inventors have conducted various studies on the development of compounds useful as cation carriers, and as a result of examining the types of plasticizers and the effects of adding fat-soluble anions, we have found that we have developed compounds that are useful as cation carriers. However, the present inventors have discovered that by appropriately selecting a plasticizer, a selective electromotive force response can be exhibited with respect to alkali metal ions, and have completed the present invention. That is, according to the present invention, an ion selective electrode membrane is provided in which a polymer membrane contains a fat-soluble anion together with a plasticizer consisting of dialkylarylphosphonate and/or o-nitrophenyl alkyl ether. . In the present invention, the selectivity for cations exhibits a completely different specific behavior depending on the type of plasticizer in the carrier-free electrode film; for example, o-nitrophenyl octyl ether is used as the plasticizer. and lithium, sodium, potassium,
Among magnesium and calcium, it shows selectivity for potassium ions, and when dioctyl phenylphosphonate is used as a plasticizer, it can show a selective electromotive force response for lithium. In order to measure the activity of cations in the present invention, a membrane consisting of a plasticizer, a polymer, and a hydrophobic anion is prepared, and the concentration of the sample solution containing various cations is kept constant on the outside of the membrane and on the inside of the membrane. The membrane is brought into contact with the standard solution prepared in the sample solution, and the potential difference generated on the surface of the membrane is measured as the potential difference between the reference electrode in the sample solution and the reference electrode inside. Next, a specific example of measuring the cation activity in a sample liquid using the polymer membrane will be shown with reference to the drawings.
Reference numeral 1 indicates a cylindrical container, which is partially composed of a polymer membrane M containing a cation-sensitive compound. 2 and 3 are reference electrodes, and 4 is a potentiometer. The sample solution A contains cations to be measured, and is usually an aqueous solution. Solution B is usually an aqueous solution containing a certain concentration of cations, and generally has a concentration of 10 ^-6 to 1M. The cation-sensitive membrane M is
Vinyl polymers and their copolymers such as polyvinyl chloride and polyethylene, condensation polymers such as polyester and polyamide, ring-opening polymers such as epoxy resins, various synthetic and natural polymers such as silicone rubber and lacquer, dialkylaryl Plasticizers of phosphonates and/or o-nitrophenyl alkyl ethers (where each alkyl group preferably has 4 to 14 carbon atoms), and tetraphenylborate, substituted analogs of tetraphenylborate It is used by forming a film from a mixture uniformly containing hydrophobic anions such as. When solutions A and B are brought into indirect contact as described above, a potential difference is generated at the membrane interface and inside the membrane.
By reading it with a potentiometer 4 using reference electrodes 2 and 3, the cation activity in the sample solution A can be measured. When the type of plasticizer in the composition of the polymer membrane for electrodes of the present invention is changed, the electromotive force response differs depending on the concentration of cations contained in solution A. Moreover, in this case,
By appropriately setting the composition of membrane M, it shows a selective electromotive force response to specific cations, so solution A containing the target cation and other cations.
By applying this method to , it is possible to selectively measure the activity of only specific cations in the solution. Next, the present invention will be explained in more detail with reference to Examples. Example: Cation activity measurement test (1) A cation activity measurement test was conducted using the apparatus shown in the drawing. O-nitrophenyl octyl ether was used as a plasticizer. The component compositions of solutions A, B and M are as follows. Solution A: 0.0001 normal, 0.001 normal, 0.01 normal, 0.1
Each aqueous solution of KCl, NaCl, LiCl of standard, 1.0 standard, 0.00002 standard, 0.0002 standard, 0.002 standard, 0.02
Normal, 0.2N aqueous solutions of CaCl ₂ and MgCl ₂ respectively. Solution B: 0.01 normal LiCL. Membrane M: 0.10 g of vinyl chloride, 0.25 g of o-nitrophenyl octyl ether, 0.003 g of tetrakis(p-chlorophenyl)borate potassium salt in THF4
ml and evaporated the solvent to form a thin film with a diameter of 4.2 cm, which was then cut out into a circle with a diameter of 5 mm. Note that this test was conducted at 25°C. The following experiments were also conducted under similar conditions. Table 1 shows the electromotive force response (mV/Δloga) and selectivity of membrane M to changes in the activity of each cation in solution A.

[Table] From the results shown in Table 1, under the conditions of test (1) for changes in the activity of six types of cations, Li ⁺ ,
It can be seen that the electromotive force response is selective to K compared to Na ⁺ and Mg ²⁺ Ca ²⁺ . Test (2) In test (1), di-nitrophenyl octyl ether was used as the plasticizer in the membrane M.
The test was conducted in the same manner except that 0.25 g of n-octylphenylphosphonate was used. The results are shown in Table 2.

【table】

[Table] From the results shown in Table 2, under the conditions of test (2) for changes in the activities of six types of cations, Na ⁺ ,
It can be seen that the electromotive force response is selective to Li ⁺ compared to K ⁺ and Mg ²⁺ Ca ²⁺ . That is, it can be seen that the selectivity changes by changing the type of plasticizer. Test (3) In test (1), G-n- was used as a plasticizer in the membrane M.
A test was conducted using a membrane prepared in the same manner except that a mixture of 0.15 g of octylphenyl phosphonate and 0.10 g of o-nitrophenyl octyl ether was used. The results are shown in Table 3.

[Table] From the results shown in Table 3, under the conditions of test (3) for changes in the activities of six types of cations, Na ⁺ ,
It can be seen that the electromotive force response is selective to Li ⁺ compared to K ⁺ and Mg ²⁺ Ca ²⁺ . Test (4) In test (1), G-n- was used as a plasticizer in the membrane M.
A test was conducted using a membrane prepared in the same manner except that a mixture of 0.01 g of octylphenyl phosphonate and 0.24 g of o-nitrophenyl octyl ether was used. The results are shown in Table 4.

[Table] From the results shown in Table 4, under the conditions of test (4) for changes in the activity of six types of cations, Na ⁺ ,
It can be seen that the electromotive force response is still selective to Li ⁺ compared to K ⁺ and Mg ²⁺ .

[Brief explanation of the drawing]

The drawing is an explanatory diagram of an apparatus for measuring the electrode membrane cation activity of the present invention. 1... Cylindrical container, 2, 3... Reference electrode, 4...
Potentiometer.

Claims (1)

[Claims] 1. An ion-selective electrode membrane comprising a polymer membrane containing a fat-soluble anion together with a plasticizer consisting of dialkyl aryl phosphonate and/or o-nitrophenyl alkyl ether.