Patent ID: 8034301

Claim:
A method of making a test paper for separating an object from a sample by filtration and for carrying thereon a reagent capable of giving a color by reaction with a specified component in the sample, the test paper comprising a porous membrane having a first surface on which the sample is applied and a second surface at which the sample is percolated and measured, the method comprising: forming a membrane on a substrate by a single casting operation of a membrane-forming stock solution containing a non-water soluble first component polymer in which the concentration range is 12 to 15 wt % and a water-soluble second component polymer in which the concentration is a range of one to three times of the non-water soluble first component polymer; treating the membrane formed by the single casting operation to form the porous membrane, wherein the porous membrane is formed to include a first layer having the first surface and a section density of 40% or less and a second layer having the second surface and a section density which exceeds 40%, and a boundary between the first layer and the second layer established within a range of ⅕ to ½ of a thickness of the porous membrane from the surface of the first layer; and wherein the first component polymer include at least one polymer selected from the group consisting of nitro cellulose, polyvinylidene fluoride, cellulose acetate, polysulfones, polyethylene and polyether sulfones, and wherein the second component polymer includes at least one polymer selected from the group consisting of polyvinylpyrolidone, polyethylene glycol, polyacrylamide, polyacrylic acid, hydroxypropyl cellulose, and methyl cellulose.