Amperometric detection of glucose and ethanol in beverages using flow cell and immobilised on screen-printed carbon electrode PQQ-dependent glucose or alcohol dehydrogenases

Enzyme electrodes containing pyrroloquinoline quinone (PQQ)-dependent alcohol (ADH) or glucose dehydrogenase (GDH) as a biological component in combination with 4-ferrocenylphenol (FP) as electron transfer mediator between PQQ and a carbon surface were constructed. The transducer was based on screen-printed carbon electrode modified with FP and enzyme. The biosensors were installed in a flow cell for glucose and ethanol measurements. The calibration graphs were linear up to 10 mM glucose and 1 mM ethanol. To eliminate the electrode background current, 2,4,7-trinitro-9-fluorenone (TNF) was electrochemically polymerised on the carbon electrode surface. Due to this procedure, interfering compounds do not influence the electrochemical response of the sensor. The flow-through biosensor system was applied to measure the glucose and ethanol concentration in various beverages containing 0.3–200 mM glucose and about 2 M ethanol. The glucose biosensor data correlated with those obtained by refractometric measurements.