Amperometric determination of acetate with a tri-enzyme based sensor

The present work describes a flow injection analysis system incorporating amperometric biosensors for acetate monitoring. Tri-enzyme-modified electrodes were fabricated by immobilizing acetate kinase (AK), pyruvate kinase (PK) and lactate dehydrogenase (LDH) into a poly(ethyleneglycole) diglycidyl ether (PEGDGE) film also containing Brilliant Cresyl Blue (BCB) as an electrochemical mediator. The concentration of acetate could be determined from the decrease in the amperometric current at +50 mV versus Ag/AgCl. Parameters, such as composition of the biosensing film, operational conditions (e.g., applied potential, flow rate) were optimized. The optimized biosensor showed a linear response to acetate in the range of 0.2–8 mM with a detection limit of 0.13 mM (calculated as 3 S/N). The acetate content of different samples (wine and vinegar) could be reliably quantified with the described biosensor.