Abstract: Enzymes which are activated by pyridoxal phosphate are assayed in a dry analytical element which includes a high coverage of pyridoxal phosphate. The coverage of pyridoxal phosphate is such that the multiplication product of the coverage and the spreading coefficient of the element results in a reagent mixture concentration of at least about 0.9 mmole per liter when a liquid sample is contacted with the element thereby eliminating the need for a preincubation of the sample with a solution containing pyridoxal phosphate. The reactions for the determination of the enzymes are initiated by contact of the dry elements with a liquid sample.

Abstract: Analytical elements and methods for the selective determination of an analyte in aqueous fluids containing the analyte. These elements and methods feature means for continuously releasing chromogenic indicator reagent from a reagent zone to a reaction zone. The continuous release means is responsive to the application of a sample of the fluid to continuously release reagent into the reaction zone at a rate producing color response corresponding to interaction of the indicator with the analyte and reduced interaction of the indicator with interferents. In preferred embodiments, albumin is determined in the presence of interfering proteins such as globulins using buffered chromogenic indicator reagent. In such embodiments, when protein interferents are present, their interference can be substantially eliminated for up to three minutes, during which time color response is substantially only from the interaction of albumin and reagent. The determination of albumin follows from such color response.

Abstract: An improved analytical element for the detection of a predetermined analyte in an aqueous liquid under highly alkaline conditions is disclosed. The element features a stable, alkaline-providing composition.Preferably, the analytical element is a multi-zone element. The element is particularly useful in total protein analysis and, when so used, an improved biuret reagent composition for use therein is also provided. Methods of using the aforementioned analytical and biuret reagent composition are also disclosed.