ENZYME-LINKED SORBENT ASSAY TO QUANTIFY D-BIOTIN IN BLOOD

An enzyme-linked sorbent assay (ELSA) is described to determine quanti tatively d-biotin in blood. This assay utilises the strong binding of streptavidin (as opposed to avidin which gave high background reaction s). A competition reaction in a microtitration plate is set up between biotin bound to the plate with biotin in the sample and streptavidin conjugated to horseradish peroxidase using tetramethylbenzidine as a m arker. This ELSA can be applied to samples with a d-biotin concentrati on of down to 20 ng litre-1. There was a good correlation coefficient of 0.981 between the ELSA and the standard microbiological method for d-biotin.