Processes for preparing barrier layer films for use in enzyme electrodes and films made thereby
First Claim
1. In a method for preparing a thin film useful as a rejection barrier layer in an enzyme containing laminated membrane structure, the improvement comprising the steps of:
- a) preparing a precursor solution comprising a cellulose ester plastic material and a solvent;
b) spreading said precursor solution over a substrate; and
c) curing said precursor solution at a temperature of from about 102°
F. to about 114°
F. for a time sufficient to remove substantially all of said solvent from said precursor solution to form a thin film of said cellulose ester plastic material and to form a pore geometry such that said film will inhibit migration of acetaminophen therethrough while permitting passage of hydrogen peroxide.
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Abstract
Methods for forming thin layer barrier layer films for use in enzyme containing laminated membranes and membranes formed thereby are disclosed. The barrier layers exhibit improved acetaminophen rejection and comprise a cellulose acetate/cellulose acetate butyrate blend. The thin layer barrier membranes are formed from a plural solvent containing solution and are cured at a critical temperature of about 102°-114° F., most preferably at about 106° F.-114° F. while traveling through a circulating hot air oven. Alternatively, the membranes can be cured at room temperature or in a stagnant oven at temperatures of from room temperature to about 175° C. (350° F.) for a period of from about 10 minutes to 1 hour.
103 Citations
50 Claims
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1. In a method for preparing a thin film useful as a rejection barrier layer in an enzyme containing laminated membrane structure, the improvement comprising the steps of:
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a) preparing a precursor solution comprising a cellulose ester plastic material and a solvent; b) spreading said precursor solution over a substrate; and c) curing said precursor solution at a temperature of from about 102°
F. to about 114°
F. for a time sufficient to remove substantially all of said solvent from said precursor solution to form a thin film of said cellulose ester plastic material and to form a pore geometry such that said film will inhibit migration of acetaminophen therethrough while permitting passage of hydrogen peroxide. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. In a method of preparing a cellulosic ester film useful as a barrier layer in an enzyme containing laminated membrane structure, the improvement comprising:
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forming a solution of cellulose acetate, cellulose acetate butyrate, a highly volatile organic solvent having a boiling point of less than 200°
C., and a liquid organic plasticizer having a boiling point of greater than 200°
C.;coating a thin layer of said solution over a substrate; heating said thin layer at a temperature of from about 102°
-114°
F. for a time sufficient to permit removal of substantially all of said volatile organic solvent and said liquid organic plasticizer from said solution and to result in a thin layer having a thickness of 2 microns or less; andsubsequently separating said thin layer from said substrate. - View Dependent Claims (19)
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20. In a method of preparing a cellulosic ester film useful as an improved acetaminophen rejection barrier layer in an enzyme containing laminated membrane structure, the improvement comprising:
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forming a precursor solution of cellulose acetate, cellulose acetate butyrate, a highly volatile organic solvent having a boiling point of less than 200°
C., and a liquid organic plasticizer having a boiling point of greater than 200°
C.;coating a thin layer of said precursor solution over a substrate; heating said thin layer at a temperature of from about 102°
-114°
F. for a time sufficient to permit removal of substantially all of said volatile organic solvent and said liquid organic plasticizer from said precursor solution to form a film having a pore geometry such that said film will inhibit migration of acetaminophen therethrough while permitting passage of hydrogen peroxide andsubsequently separating said film from said substrate;
said coating comprising spreading said precursor solution over said substrate to a sufficient depth to provide after said heating, a film thickness of 2 microns or less. - View Dependent Claims (21)
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22. In a method of preparing a cellulose ester film useful as an improved barrier layer in an enzyme containing laminated membrane structure, the improvement comprising:
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forming a precursor solution of cellulose acetate, cellulose acetate butyrate, a highly volatile organic solvent selected from the group consisting of nitromethane, dimethylformamide and cyclohexanone, and a liquid organic plasticizer chosen from the group consisting of γ
-butyrolactone and valerolactone, wherein said cellulose acetate and cellulose acetate butyrate are present in an amount, by weight, of 10-40 wt. % based upon the weight of said solution;adding a thinner to said precursor solution;
then spreading a thin layer of said solution over a substrate;curing said thin layer of precursor solution at a temperature of from 102°
-114°
F. for a time of about 0.5 to 1.5 minutes to form a film having a pore geometry such that said film will inhibit migration of acetaminophen therethrough while permitting passage of hydrogen peroxide;
then separating said film from said substrate, said spreading comprising spreading a sufficient depth of said precursor solution over said substrate sufficient to provide after said curing, a film thickness of 2 microns or less. - View Dependent Claims (23)
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24. In a method for preparing a thin film useful as a interference rejection barrier in an enzyme containing laminated membrane the improvement comprising the steps of:
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(a) preparing a precursor solution comprising a cellulose ester plastic material and a solvent; (b) spreading said precursor solution over a substrate; (c) curing said precursor solution at a temperature from about room temperature to about 175°
C. (350°
F.) for a time sufficient to remove substantially all of said solvent from said precursor solution to form a thin film of cellulose ester plastic material of about 2 microns or less in thickness and to form a pore geometry such that said film will inhibit migration of an interfering compound selected from the group consisting of acetaminophen, hydroxyurea, isoniazid, and potassium iodide therethrough while permitting passage of hydrogen peroxide therethrough. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. In a polarographic measurement system of the type having an electrode, an analyte containing solution, and a laminated enzyme containing membrane interposed between said electrode and said analyte containing solution wherein said analyte containing solution contacts said enzyme and produces an electrically measurable reaction product that passes through said laminated membrane for detection at said electrode, an improved method for inhibiting interference with said detection comprising:
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(a) providing an interference rejection layer of said laminated enzyme containing membrane, said interference rejection layer made by the steps of (i) preparing a precursor solution comprising a cellulose ester plastic material and a solvent; (ii) spreading said precursor solution over a substrate; and (iii) curing said precursor solution at a temperature from about room temperature to about 175°
C. (350°
F.) for a time to remove substantially all of said solvent from said precursor solution to form a thin film of cellulose ester plastic material of about 2 microns or less in thickness(b) placing said interference rejection layer adjacent said electrode; (c) providing an analyte solution comprising an analyte and an interfering compound selected from the group consisting of acetaminophen, hydroxyurea, isoniazid, and potassium iodide, (d) contacting said laminated membrane with said analyte solution, and (e) inhibiting passage of said interfering compounds through said interference rejection layer while permitting said electrically measurable species to pass through said laminated membrane for detection at said electrode. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50)
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Specification