Sensitive Simultaneous Determinations of 1,2-Dihydroxynaphthalene and Catechol by an Amperometric Biosensor

An amperometric biosensor for 1,2-dihydroxynaphthalene (DHN) and catechol (Cat) has been developed in order to monitor the biodegradaton of polycyclic aromatic hydrocarbons (PAHs). DHN is a common intermediary metabolite in naphthalene and phenanthrene degradation, while Cat is produced by further degradation. These compounds were detected by a biosensor modified with pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH). The biosensor was based on signal amplification by enzyme-catalyzed redox cycling and was able to detect DHN and Cat at very low concentrations down to 10^-9 M. Since the anodic waves of DHN and Cat were well separated, simultaneous determinations of these compounds were possible. Although the current signal for DHN was reduced in repeated measurements due to the oxidative polymerization of DHN, it can be avoided when the concentration of DHN was sufficiently low (<1 μM).