| abstract |
A test device and method of determining the presence or concentration of a predetermined ion, such as a cation of medical interest, like sodium, potassium, calcium, magnesium or lithium, in an aqueous test sample are disclosed. The test device includes a test pad comprising a hydrophilic indicator reagent composition capable of interacting with a predetermined ion, or electrolyte, to produce a detectable or measurable response. The hydrophilic indicator reagent composition comprises an ion specific ionophore, a reporter substance, and a stabilizer compound, such a gelatin. The hydrophilic indicator reagent composition, either as a film or layer, or after incorporation into a suitable carrier matrix, provides a test pad of sufficient sensitivity to the predetermined ion to achieve an accurate and trustworthy electrolyte assay of an aqueous test sample, such as the plasma or serum of a whole blood sample, by a dry phase test strip assay. |