Lower concentration than expected

Reconstitution volume (for kits with lyophilized calibrators or controls)

The lyophilized calibrators have been reconstituted with a smaller volume than stated in the Directions for Use.

Reconstitute with recommended volume of redistilled water. Mix well before using. Check that there is no un-dissolved material left in the stopper of the bottle. The vial can be placed on a rotating mixer to ensure that all of the powder comes in contact with the water.

Hook effect

The sample contains a very high amount of antigen and is therefore given a falsely low result because of the hook effect.

Dilute and re-run the samples.

Dilution

The samples and/or controls have been over diluted.

Always use the volumes recommended for samples, calibrators, controls and enzyme conjugate solution. Check that pipettes are calibrated.