Multilayer analytical element for quantitative analysis of bilirubin

Abstract

A multilayer analytical element for quantitative analysis of bilirubin in a liquid sample by a diazo method, which comprises a laminated structure consisting essentially of: (1) a porous reagent layer containing an acidic binder and a diazonium salt being reactive to bilirubin to produce azobilirubin; (2) an absorbent layer capable of absorbing an excessive liquid portion; and (3) a liquid-impermeable light-transmissive support.

We claim: 
     
       1. A multilayer analytical element for quantitative analysis of bilirubin in a liquid sample which comprises, in this order, (1) a porous reagent layer containing an acidic binder and a diazonium salt being reactive to bilirubin to produce azobilirubin;   (2) an absorbent layer comprising a hydrophilic polymer capable of absorbing a solvent in a liquid sample without accepting bilirubin in a liquid sample diffusing into said porous reagent layer; and   (3) a liquid-impermeable light-transmissive support.   
     
     
       2. The analytical element claimed in claim 1, in which said absorbent layer comprises a hydrophilic polymer having a degree of swelling in water at 30° C. in the range of 1.5 to 30 times as much as its original volume. 
     
     
       3. The analytical element claimed in claim 1 or 2, in which said absorbent layer contains a basic polymer. 
     
     
       4. The analytical element claimed in claim 3, in which said basic polymer is: a homopolymer of an unsaturated monomer selected from the group consisting of 2-vinylpyridine, 4-vinylpyridine, N-vinylimidazole, 1-vinyl-3-alkyl-2,3-dihydroimidazole, 2-vinyl-1-alkyl-imidazole, (dialkylamino)alkyl acrylate, (dialkylamino) alkyl methacrylate, N-[(dialkylamino)alkyl]acrylamide, and N-[(dialkylamino)alkyl]methacrylamide;   a copolymer of said unsaturated monomers; or   a copolymer of said unsaturated monomer and other unsaturated monomer than said unsaturated monomer.   
     
     
       5. The analytical element claimed in claim 1 or 2, in which said acidic binder is: a homopolymer of unsaturated monomer selected from the group consisting of p-styrenesulfonic acid, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, maleic acid monoamide, maleic acid monoester, N-(sulfoalkyl)acrylamide, and N-(sulfoalkyl)methacrylamide;   a copolymer of said unsaturated monomers; or   a copolymer of said unsaturated monomer and other unsaturated monomer than said unsaturated monomer.   
     
     
       6. The analytical element as claimed in claim 1 wherein the absorbent layer comprises a material selected from the group consisting of gelatin, dextran, starch, modified starch, hydroxyethyl-modified agarose, polyvinyl alcohol, a homopolymer of hydroxyethyl acrylate, a homopolymer of hydroxyethyl methacrylate, a homopolymer of N-(hydroxyalkyl)acrylamide, and copolymers of acrylamide with one or more monomers selected from the group consisting of hydroxyethyl acrylate, hydroxyethyl methacrylate and N-(hydroxyalkyl)-acrylamide. 
     
     
       7. The analytical element as claimed in claim 1 which further contains a light-blocking layer. 
     
     
       8. A multilayer analytical element for quantitative analysis of bilirubin in a liquid sample which comprises, in this order, (1) a porous reagent layer containing an acidic binder and a diazonium salt being reactive to bilirubin to produce azobilirubin;   (2) a layer for presenting diffusion of bilirubin;   (3) an absorbent layer comprising a hydrophilic polymer capable of absorbing a solvent in a liquid sample without accepting bilirubin in a liquid sample diffusing into said porous reagent layer; and   (4) a liquid-impermeable light-transmissive support.