Structure of the test tab

5 cm glass fibre matrix is fitted into a plastic case (tab) (Fig. 53). The prepared antibody can now be applied to the glass fibre matrix. The specific antibody for each test is firmly crosslinked into this matrix by a carrier antibody, the bonding by the carrier antibody being effected by a chemical bond. The specific antibody is produced in the rabbit the antibody for fixation is an anti-rabbit antibody from the goat. The glass fibre matrix is used to prevent unspecific reactions. On these carriers prepared in this manner the tests can be performed according to the competitive, sequential or sandwich technique. 

After having undergone a drying process, the tabs are ready for use and can be packed together with a desiccant. TTiey must be stored in the refrigerator at +2°C to +8°C. A temperature of 38°C has been chosen as the reaction temperature measurements must be performed at a temperature of 40°C. 

With the sequential analysis technique the sample is applied to the centre of the tab. After a brief incubation phase the enzyme-labelled antigen can be pipetted onto the carrier. After a subsequent, somewhat longer period, the antigen that is not bound to the antibody is washed out in peripheral direction. 

With the competitive test the patient serum containing the antigen is mixed with the enzyme-labelled antigen in the sample container. An aliquot from this mixture is then applied to the tab. After the incubation period the excess antigen is washed out towards the margin of the carrier by means of the wash solution. 

With the sandwich technique a labelled antibody is applied instead of a labelled antigen. The labelled antibody becomes bound to the antigens of the sample after these adhere to the antibody in the matrix. The excess amount of antibody is likewise washed out from the centre of the carrier by means of a 

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