Continuous release of reagent in an analytical element to reduce assay interference
First Claim
1. A multizone dry analytical element comprising(a) reaction zone for receiving an aqueous fluid to be subjected to an assay for the selective determination of an analyte in the fluid, which fluid contains said analyte;
- (b) means forming a dry reagent zone impermeable to said analyte and interferents to an assay for said analyte, said reagent zone being in fluid contact with said reaction zone when said element is contacted with a sample of said fluid, said reagent zone including a reagent composition comprising a chromogenic indicator which interacts with said analyte and interferents to produce a color response; and
(c) release means responsive to contact of said sample with said element for continuously releasing said reagent composition from said reagent zone to said reaction zone at a rate sufficient to produce an analyte color response corresponding to;
(1) the interaction of said indicator with said analyte, and(2) reduced interaction of said indicator with interferents.
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Accused Products
Abstract
Analytical elements and methods for the selective determination of an analyte in aqueous fluids containing the analyte. These elements and methods feature means for continuously releasing chromogenic indicator reagent from a reagent zone to a reaction zone. The continuous release means is responsive to the application of a sample of the fluid to continuously release reagent into the reaction zone at a rate producing color response corresponding to interaction of the indicator with the analyte and reduced interaction of the indicator with interferents. In preferred embodiments, albumin is determined in the presence of interfering proteins such as globulins using buffered chromogenic indicator reagent. In such embodiments, when protein interferents are present, their interference can be substantially eliminated for up to three minutes, during which time color response is substantially only from the interaction of albumin and reagent. The determination of albumin follows from such color response.
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Citations
27 Claims
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1. A multizone dry analytical element comprising
(a) reaction zone for receiving an aqueous fluid to be subjected to an assay for the selective determination of an analyte in the fluid, which fluid contains said analyte; -
(b) means forming a dry reagent zone impermeable to said analyte and interferents to an assay for said analyte, said reagent zone being in fluid contact with said reaction zone when said element is contacted with a sample of said fluid, said reagent zone including a reagent composition comprising a chromogenic indicator which interacts with said analyte and interferents to produce a color response; and (c) release means responsive to contact of said sample with said element for continuously releasing said reagent composition from said reagent zone to said reaction zone at a rate sufficient to produce an analyte color response corresponding to; (1) the interaction of said indicator with said analyte, and (2) reduced interaction of said indicator with interferents. - View Dependent Claims (2, 3, 4, 23, 24)
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5. A multizone dry analytical element comprising
(a) reaction zone for receiving, and for the selective determination of magnesium in, an aqueous fluid sample containing magnesium; -
(b) means forming a dry reagent zone impermeable to magnesium and calcium, in fluid contact with said reaction zone when said element is contacted with said sample, said reagent zone comprising a reagent composition comprising a chromogenic indicator which interacts with magnesium and calcium to produce a color response; and (c) release means responsive to contact of said sample with said element for continuously releasing said reagent composition from said reagent zone to said reaction zone at a rate sufficient to produce a magnesium color response corresponding to; (1) the interaction of said indicator with magnesium, and (2) reduced interaction of said indicator with calcium. - View Dependent Claims (6, 7, 8, 9)
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10. A multizone dry analytical element comprising
(a) reaction zone for receiving, and for the selective determination of albumin in, an aqueous fluid sample containing albumin; -
(b) a buffer (c) means forming a dry reagent zone, impermeable to albumin and protein interferents to an assay for albumin, said reagent zone being in fluid contact with said reaction zone when said element is contacted with said sample, said reagent zone comprising a reagent composition containing a chromogenic indicator which interacts with albumin and protein interferents in the presence of said buffer to produce a color response, and (d) means responsive to contact of said sample with said element for continuously releasing said reagent composition from said reagent zone to said reaction zone at a rate sufficient to produce an albumin color response corresponding to the interaction of said indicator with albumin and reduced interaction of said indicator with protein interferents. - View Dependent Claims (11, 12, 13)
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14. A multizone dry analytical element comprising a reaction zone for receiving, and for the selective determination of albumin in, an aqueous fluid sample containing albumin;
- means forming a dry, polymeric reagent zone, impermeable to albumin and protein interferents to assay for albumin, said reagent zone being in fluid contact with said reaction zone when the reaction zone is contacted with said sample;
said reagent zone comprising, in a polymeric binder, a reagent composition comprising a buffer and a chromogenic indicator which interacts with albumin and protein interferents in the presence of said buffer to produce a color response, said polymer being responsive to contact of said sample with said element for continuously releasing said reagent composition from said reagent zone to said reaction zone at a rate sufficient to produce an albumin color response corresponding to the interaction of said indicator with albumin and reduced interaction of said indicator with protein interferents. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
- means forming a dry, polymeric reagent zone, impermeable to albumin and protein interferents to assay for albumin, said reagent zone being in fluid contact with said reaction zone when the reaction zone is contacted with said sample;
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25. A method for the selective determination of an analyte in an aqueous fluid containing said analyte, said method comprising
(a) contacting a sample of said fluid with a reaction zone of a multizone dry analytical element having a reaction zone in fluid contact with a dry reagent zone; - said reagent zone being impermeable to said analyte and interferents to an assay for said analyte and includes a reagent composition comprising a chromogenic indicator which interacts with said analyte and interferents to produce a color response; and
said contacting causes release of said reagent composition from said reagent zone to said reaction zone at a rate sufficient to produce an analyte color response corresponding to(1) the interaction of said indicator with said analyte, and (2) reduced interaction of said indicator with interferents; and (b) determining said analyte from said analyte color response.
- said reagent zone being impermeable to said analyte and interferents to an assay for said analyte and includes a reagent composition comprising a chromogenic indicator which interacts with said analyte and interferents to produce a color response; and
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26. A method for the selective determination of albumin in an aqueous fluid containing albumin, said method comprising
(a) contacting a sample of said fluid with reaction layer of a multilayer dry analytical element having a reaction layer in fluid contact with a dry reagent layer; - said reagent layer being impermeable to albumin and protein interferents to an assay for albumin and includes in a polymeric binder, a reagent composition comprising a buffer and a chromogenic indicator which interacts with albumin and protein interferents in the presence of said buffer to produce a color response, and said contacting causes said polymer to release said reagent composition from said reagent layer to said reaction layer at a rate sufficient to produce an albumin color response corresponding to the interaction of said indicator with albumin and reduced interaction of said indicator with protein interferents; and
(b) determining albumin from said albumin color response.
- said reagent layer being impermeable to albumin and protein interferents to an assay for albumin and includes in a polymeric binder, a reagent composition comprising a buffer and a chromogenic indicator which interacts with albumin and protein interferents in the presence of said buffer to produce a color response, and said contacting causes said polymer to release said reagent composition from said reagent layer to said reaction layer at a rate sufficient to produce an albumin color response corresponding to the interaction of said indicator with albumin and reduced interaction of said indicator with protein interferents; and
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27. A method for reducing protein interference in an analytical determination for albumin in a fluid sample containing albumin and protein interferents to an assay for albumin, said method comprising
(a) contacting a sample of said fluid with a reaction layer of a multilayer dry analytical element having a reaction layer in fluid contact with a dry reagent layer; - said reagent layer being impermeable to albumin and said protein interferents and includes in a polymeric binder, a reagent composition comprising a buffer sufficient to maintain said fluid at a non-alkaline pH and a sulphonphthalein chromogenic indicator which interacts with albumin and protein interferents in the presence of said buffer to produce a color response, and said contacting causes said polymer to release said reagent composition from said reagent layer to said reaction layer at a rate sufficient to produce an albumin color response corresponding to the interaction of said indicator with albumin and reduced interaction of said indicator with protein interferents; and
(b) determining albumin from said albumin color response.
- said reagent layer being impermeable to albumin and said protein interferents and includes in a polymeric binder, a reagent composition comprising a buffer sufficient to maintain said fluid at a non-alkaline pH and a sulphonphthalein chromogenic indicator which interacts with albumin and protein interferents in the presence of said buffer to produce a color response, and said contacting causes said polymer to release said reagent composition from said reagent layer to said reaction layer at a rate sufficient to produce an albumin color response corresponding to the interaction of said indicator with albumin and reduced interaction of said indicator with protein interferents; and
Specification