Ion-selective electrode and method of making said electrode

• US 4,287,042 A
• Filed: 03/06/1980
• Issued: 09/01/1981
• Est. Priority Date: 03/09/1979
• Status: Expired due to Term

• Current Assignee: National Research Development Corporation
• Original Assignee: National Research Development Corporation
• Inventors: Ellis, Andrew T., Ebdon, Leslie C., Corfield, George C.
• Primary Examiner(s): Kaplan, G. L.
• Application Number:
  US06/127,749
• Time in Patent Office: 544 Days
• Field of Search: 204/195 M, 204/296
• US Class Current: 204/418
• CPC Class Codes: G01N 27/3335 the membrane containing at least one organic component G01N27/3271 takes precedence; aspects concerning the enzyme reagent in enzyme electrodes C12Q1/001

Abstract

An ion-selective electrode comprises a standard solution of the ion, such as calcium, and, retaining the solution, a membrane including sensor groups. The sensor groups are secured in the membrane by cross-linking. The membrane may be a styrene-butadiene-styrene triblock elastomeric copolymer, with dialkyl phosphate cross-linked sensor groups resulting from a cross-linking reaction between the membrane and diallyl phosphoric acid.

Claims

1. An ion-selective electrode comprising a standard solution of the ion and, retaining the solution, a membrane comprising an unsaturated organic polymer having sensor groups covalently bonded to said polymer, characterized in that the unsaturated organic polymer is cross-linked at least in part through a covalently-bonded sensor group of the formula ##STR2## where A and B are unsaturated moieties cross-linking the polymer, whereby the electrode is calcium-selective.

2. An ion-selective electrode according to claim 1, characterised in that the membrane comprises an unsaturated linear polymer.

3. An ion-selective electrode according to claim 2, characterised in that the unsaturated linear polymer is a styrene-butadiene-styrene triblock copolymer.

4. An ion-selective electrode according to claim 1, characterised in that the membrane displays elastomeric properties.

5. An ion-selective electrode according to claim 1, characterised in that the membrane contains a covalently bound mediator.

6. An ion-selective electrode according to claim 5, characterised in that the mediator is cross-linked to the membrane.

7. An ion-selective electrode according to claim 5, characterised in that the mediator is methyl methacrylate.

8. An ion-selective electrode according to claim 1, characterised in that the sensor group is an organophosphate or an organophosphonate.

9. An ion-selective electrode according to claim 9, characterised in that the sensor group is dialkyl phosphate.

10. A method of making the ion-selective electrode of claim 9, characterised in that the dialkyl phosphate is made directly from a cross-linking reaction of diallyl phosphoric acid with the membrane yielding dialkyl phosphate.

11. A method of making the ion-selective electrode of claim 9, characterized in that the dialkyl phosphate is made indirectly from a cross-linking reaction of a compound selected from the group consisting of triallyl phosphate, tri(ω

-undecenyl)phosphate and diallyl phenylphosphonate with the membrane yielding trialkyl phosphate.

12. A method according to claim 11, characterised in that the cross-linking reaction is free-radical initiated.

13. A method according to claim 12, characterised in that α

,α

-azobisisobutyronitrile is present as a free-radical initiator.

14. A method according to claim 12, characterised in that the proportion of free-radical initiator is 1 to 5% by weight with respect to the membrane.

15. A method according to claim 14, characterised in that the said proportion is 2 to 3% by weight.

16. A method according to claim 12, characterised in that the free radicals are generated by ultra-violet irradiation.

17. A method according to claim 11, characterised in that the cross-linking reaction is followed by hydrolysis converting the trialkyl phosphate to dialkyl phosphate.

18. A method according to claim 17, characterised in that the hydrolysis lasts at least 1 hour.

19. A method according to claim 18, characterised in that the hydrolysis lasts at least 3 hours.

20. A method according to claim 19, characterised in that the hydrolysis lasts at least 4 hours.

21. A method according to claim 17, characterised in that the hydrolysis lasts up to 20 hours.

22. A method according to claim 21, characterised in that the hydrolysis lasts up to 10 hours.

23. A method according to claim 18, characterised in that the hydrolysis is by aqueous alkali in a concentration of up to 20% by weight.

24. A method according to claim 17, characterised in that the hydrolysis is by up to 8% by weight alkali in alcohol.

25. A method according to claim 11, characterised in that the phosphate according to the cross-linking reaction is present in a proportion of 0.3 to 10% by weight with respect to the membrane.

26. A method according to claim 25, wherein the said proportion is 4 to 6% by weight.