Analytical element and method for determination of theophylline by enzyme inhibition
First Claim
1. A dry analytical element for the determination of theophylline comprising, in fluid contact, a porous spreading zone and at least one additional zone,said element containing an isoenzyme of alkaline phosphatase which is capable of acting on a substrate for said isoenzyme at a pH of 9 or less, and a substrate for said isoenzyme, provided said phosphatase and substrate are in different zones of said element,said element further containing a buffer which is capable of maintaining the pH at 9 or less during said determination, provided that substantially all of said buffer is in said porous spreading zone.
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Accused Products
Abstract
Theophylline can be determined with an analytical element and method which utilize the inhibition, by theophylline, of alkaline phosphatase activity on an appropriate substrate. The assay is carried out at a pH of 9 or less. The element comprises a porous spreading zone and at least one other zone in fluid contact with the spreading zone. The isoenzyme of alkaline phosphatase and a suitable substrate for the isoenzyme are located in different zones of the element. The element also contains a buffer for maintaining the pH at 9 or less, substantially all of which is located in the spreading zone.
9 Citations
18 Claims
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1. A dry analytical element for the determination of theophylline comprising, in fluid contact, a porous spreading zone and at least one additional zone,
said element containing an isoenzyme of alkaline phosphatase which is capable of acting on a substrate for said isoenzyme at a pH of 9 or less, and a substrate for said isoenzyme, provided said phosphatase and substrate are in different zones of said element, said element further containing a buffer which is capable of maintaining the pH at 9 or less during said determination, provided that substantially all of said buffer is in said porous spreading zone.
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7. An analytical element for the determination of theophylline comprising:
- a support having thereon, in order and in fluid contact;
a first layer containing an isoenzyme of alkaline phosphatase which is capable of acting on a substrate for said isoenzyme at a pH of 9 or less, a radiation-blocking layer, and a porous spreading layer containing a substrate for said isoenzyme, said element further containing a buffer which is capable of maintaining the pH at 9 or less during said determination, provided that substantially all of said buffer is in said porous spreading layer. - View Dependent Claims (8, 9, 10, 11, 12)
- a support having thereon, in order and in fluid contact;
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13. A method for the determination of theophylline comprising the steps of:
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A. at a pH of 9 or less, contacting a sample of a biological fluid suspected of containing theophylline with a dry analytical element comprising, in fluid contact, a porous spreading zone and at least one additional zone, said element containing an isoenzyme of alkaline phosphatase which is capable of acting on a substrate for said isoenzyme at a pH of 9 or less, and a substrate for said isoenzyme, provided said phosphatase and substrate are in different zones of said element, said element further containing a buffer which is capable of maintaining the pH at 9 or less during said determination, provided that substantially all of said buffer is in said porous spreading zone, and B. determining a detectable change resulting from said contact as an indication of the amount of theophylline in said biological fluids. - View Dependent Claims (14, 15)
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16. A method for the determination of theophylline comprising the steps of:
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A. at a pH of 9 or less, contacting a sample of a human biological fluid suspected of containing theophylline with a dry analytical element comprising;
a support having thereon, in order and in fluid contact;a first layer containing an isoenzyme of alkaline phosphatase which is capable of acting on a substrate for said isoenzyme at a pH of 9 or less, a radiation-blocking layer, and a porous spreading layer containing a substrate for said isoenzyme, said element further containing a buffer which is capable of maintaining the pH at 9 or less during said determination, provided that substantially all of said buffer is in said porous spreading layer, and B. determining a detectable change resulting from said contact as an indication of the amount of theophylline in said human biological fluid. - View Dependent Claims (17, 18)
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Specification