Flow-injection binding assays: a way to increase the speed in binding analyses

A flow-injection analysis system was equipped with a small column containing immobilized concanavalin A. Pulses containing glucosides or glycoproteins were passed over the column, the lectin bound the carbohydrates. By using horseradish peroxidase as a labeled carbohydrate and letting it compete with other glucosides or mannosides a competitive binding assay for the latter was set up. When the enzyme activity had been evaluated, the column was rinsed and reconditioned, allowing a new assay to be run. To speed up the assay, substrates for the enzyme marker, peroxidase, were present in the perfusing buffer. A computerized evaluation of the absorbance peak allowed the time of the assay cycle to be reduced to 70 s. The sensitivity of this binding assay was fully comparable with those reported for other systems using the same reactants.