ORGANIC-PHASE BIOSENSING OF ENZYME-INHIBITORS

Organic-phase biosensors, suitable for monitoring low levels of enzyme inhibitors in non-aqueous media, are described. The inhibition of tyr osinase and horseradish peroxidase by thiourea, benzoic acid, diethyld ithiocarbamate, hydroxylammonium sulphate and mercaptoethanol is explo ited for highly sensitive amperometric measurements in organic media. Fast on-line monitoring of various inhibitors is illustrated in a flow -injection operation, with an enzyme inhibition based detector and an acetonitrile carrier solution. Repetitive injections of a 1 X 10(-4) M diethyldithiocarbamate solution (at a rate of 60 samples per hour) yi elded a relative standard deviation of 3.3%. Sensing advantages accrue from such operation, particularly applicability to inhibitors with po or water solubility and solvent-induced changes in the mechanism of in hibition, are discussed.