Dry analysis element having a constant blank value and process for preparing the same

An analysis element comprising:

• a first water-permeable layer containing a reagent composition capable of producing an optically detectable substance in the presence of a predetermined analyte in an aqueous sample, and
• a second water-permeable layer containing a fogging agent which is detectable by the same method and at the same wavelength as that for detecting said optically detectable substance, said fogging agent being capable of raising the blank level at said wavelength of the element to a predetermined constant level,
• wherein said fogging agent and said optically detectable substance are identical.

In a process for preparing an analysis element comprising a water-permeable layer containing a reagent composition capable of producing an optically detectable substance in the presence of a predetermined analyte in an aqueous sample,

• an improved process which comprises the step of adding a fogging agent which is detectable by the same method and at the same wavelength as that for detecting said optically detectable substance to said water-permeable layer, said fogging agent being capable of raising the blank level at said wavelength of the element to a predetermined constant level,
• wherein said fogging agent and said optically detectable substance are identical.

In a process for preparing an analysis element comprising at least two water-permeable layers, the first water-permeable layer containing a reagent composition capable of producing an optically detectable substance in the presence of a predetermined analyte in an aqueous sample,

• an improved process which comprises the step of preparing a second water permeable layer by adding a fogging agent which is detectable by the same method and at the same wavelength as that for detecting said optically detectable substance, said fogging agent being capable of raising the blank level at said wavelength of the element to a predetermined constant level,
• wherein said fogging agent and said optically detectable substance are identical.