Method and test strips for determining an analyte

Immunological detection methods with enzyme labels have been of considerable importance in quantitative determinations of analytes for many years. The determinations are, owing to the large number of steps necessary, time-consuming and costly, and they require trained users to carry them out. The test strip according to the novel method makes it possible to carry out quantitative immunological determinations in a short time and without special knowledge. The test strip consists of four zones made of porous material which are fixed on a common base element and are in liquid contact. After entry of the sample liquid into the test strips it flows through the individual elements and there dissolves the reagents necessary for the reactions. An enzyme-labelled analyte analogue and an antibody against the sample analyte are used for the determination. Sample analyte and enzyme-labelled analogue compete for binding to the antibody. The unbound enzyme-labelled analogue is passed into a zone in which a substrate is converted by the labelling enzyme. The reacted amount of substrate is proportional to the amount of the analyte. Test strips for determining cortisol in saliva.