Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1997-07-25
1999-01-26
Niland, Patrick D.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
128635, 128639, 128642, 204400, 204413, 204415, 204418, 204520, 422 8203, 429209, 429250, 436 74, 524588, 524589, 524590, C08J 300, C08K 320, C08L 7500, C08L 8300
Patent
active
058639721
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a composition consisting of a randomly segmented thermoplastic polyurethane, a polyurea or a polyurethane urea and a calcium ionophore, to an electrode for calcium analysis comprising said composition in the form of a membrane, to a process for the electrochemical analysis of Ca++ ions in solution as well as to the use of said composition for the electrochemical analysis of Ca.sup.++ ions.
The electrochemical analysis of K.sup.+ oder Ca.sup.++ ions has been known for some time and is described, inter alia, in Analytica Chimica Acta 67 (1973). This publication in particular compares the properties of the valinomycin/potassium electrode in a PVC matrix and in a polyurethane matrix. The membranes prepared from PVC must additionally contain at least one organic solvent or a plasticiser such as dioctyl phthalate to achieve the requisite electrochemical properties and the necessary mechanical properties such as flexibility and adhesion, e.g. on glass. Although the proposed polyurethane membranes have suitable mechanical properties even without the addition of a solvent or plasticiser, their electromechanical behaviour is markedly inferior to the system PVC/solvent. By adding dioctyl phthalate to the polyurethane matrix electrochemical properties can be achieved which are comparable to those of the system PVC/solvent.
U.S. Pat. No. 4,816,130 proposes the use of crosslinked polyurethanes having a hard segment component of 20 to 50% as membrane material in electrochemical sensors for blood analysis. The polyurethane membranes consist of a polyether glycol, a low molecular chain extender molecule such as butanediol, a diisocyanate and a trifunctional cross-linker, typically trimethylolpropane. The crosslinked polymers are no longer soluble in organic solvents. These membranes absorb from 50 to 120% of water, based on their dry weight.
Japanese patent specification No. Sho 62-65216 discloses the use of polyurethanes which have particularly good compatibility with blood and body tissue for in vivo examination. Said polyurethanes are block copolymers, one component of which consists of a hydroxyl-terminated ethylene oxide/polydimethylsiloxane/ethylene oxide triblock. The other components are diisocyanates, e.g. 4,4'-diphenylmethanediisocyanates, hydroxyl-terminated ethylene oxide/propylene oxide/ethylene oxide block copolymeres. An essential feature of these membranes is their low risk of causing thrombosis and that they have only a minor influence on the blood physiological functions. Nothing is known about their sensitivity, response time, selectivity and life span in Ca.sup.++ sensors.
Although polyurethane membranes have already been proposed in the literature for use in electrochemical sensing, PVC is most often used as matrix material for K.sup.+ and Ca.sup.++ sensing. The advantages and disadvantages of this polymer are known and described, inter alia, by U. Oesch and W. Simon in Anal. Chem. 1980, 52, 692-700. The advantages are the rapid response time as well as the high sensitivity and selectivity. One of the disadvantages is that a plasticiser must be used in any case which is then slowly dissolved out during analysis, whereby in particular in in vivo analysis, undesirable substances may be left in the blood circulation. If continuous flow measurements are carried out, there may often be a particularly rapid loss of plasticiser or solvent which can interfere with the measurements, as sensitivity and response time may be altered thereby. The loss of plasticiser also has a negative effect on the life span of the electrode, which becomes brittle as loss increases and is no longer operable.
The present invention relates to a composition containing a plasticiser-free thermoplastic randomly segmented polyurethane which is soluble in organic solvents, a polyurea or a polyurethane urea as membrane material for the electrochemical Ca.sup.++ sensors. The membrane has excellent response time, high sensitivity and selectivity. The adhesive properties on e.g. glass in an aqueous electrolyte are ve
REFERENCES:
patent: 4816130 (1989-03-01), Karakelle et al.
patent: 5035791 (1991-07-01), Battilotti et al.
Fiedler, U. et al., "Selectrode-The Universal Ion-Selective electrode"Analytica Chimica Acta 67 (1973) 179-193.
Oesch, U. et al., "Life Time of Neutral Carrier Based Ion-Selective Liquid-Membrane Electrodes" Anal. Chem. 52 (1980) 692-700.
Simon, W. et al., "Calcium-Selective Electrodes" Ann. N.Y. Acad. Sci. 307/52 (1978) 52-69.
Database WPI Week 8844, Derwent Publications Ltd., London, GB; AN 88-311565 & JP,A, 63229356 (Agency of Ind. Sci. Tech.) Sep. 26. 1988 (see abstract).
Beckelmann Dirk
Berger Joseph
Blackburn Robert P.
Chiron Diagnostics Corporation
Morgenstern Arthur S.
Niland Patrick D.
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