Color fixed chromogenic analytical element

A method for preparing an analytical element for determining glucose in a liquid sample which method comprises the steps of:

• (a) impregnating a carrier with a first solution, having a pH not greater than about 2.5, which comprises an interpolymer of methyl vinyl ether and maleic anhydride present in a concentration from about 0.5 to about 0.75 percent of the first solution on a weight to weight basis and 3,3',5,5'-tetramethylbenzidine dihydrochloride, in a molar concentration greater than that of the interpolymer, in an aqueous solvent and drying the carrier;
• (b) impregnating the carrier of (a) with a solution, having a pH of at least about 7.0, which comprises glucose oxidase and peroxidase in an aqueous solvent and drying the carrier;
• and
• (c) impregnating the carrier of (b) with a solution of ethyl cellulose in a solvent which consists essentially of toluene, from about 80 to about 95 percent of the solvent, and ethanol, from about 5 to about 20 percent of the solvent, the toluene and ethanol being together 100 percent, and drying the carrier.

A method for preparing an analytical element for determining cholesterol in a liquid sample which method comprises the steps of:

• (a) impregnating a carrier with a first solution having a pH not greater than about 2.5, which comprises an interpolymer of methyl vinyl ether and maleic anhydride present in a concentration from about 0.5 to about 0.75% of the first solution on a weight to weight basis and 3,3',5,5'-tetramethylbenzidine dihydrocholoride, with the 3,3',5,5'-tetramethylbenzidine in a molar concentration greater than that of the interpolymer, in an aqueous solvent and drying the carrier;
• (b) impregnating the carrier of (a) with a solution, having a pH of at least about 7.0, which comprises cholesterol oxidase, cholesterol esterase and peroxidase in an aqueous solvent and drying the carrier;
• and
• (c) impregnating the carrier of (b) with a solution of ethyl cellulose and a solvent which consists essentially of toluene, from about 80 to about 95% of the solvent, and ethanol, from about 5 to about 20% of the solvent, the toluene and ethanol being together 100%, and drying the carrier.