Shown here as an application example is a serological assay in a microtiter plate (MTP): Antigens covalently coupled to beads (Fig. 1) react with antibodies in the sample (Fig. 2). A detection antibody is then added to detect these antibodies. The detection antibody is phycoerythrin (PE)-labelled (Fig. 3). Depending on the test format, wash steps are carried out after individual incubation steps.

In case no PE-labelled detection antibodies are available, the Biotin-Streptavidin system can be used.

As soon as the detection reaction is over, the sample is measured using the Luminex- system. One laser classifies the bead populations and a second laser quantifies the amount of analyte based on the proportion of bound PE. (Fig. 4/5). Based on the signals of 100 beads, the median fluorescence intensity (MFI) of a bead population is established.

Quantification of individual analytes can be performed by means of an external standard curve or a control, depending on the test format.