Amperometric flow injection determination of fructose in honey with a carbon paste sensor based on fructose dehydrogenase

An enzyme carbon paste electrode for quantitation of fructose in a flow injection analysis (FIA) system is developed. The sensor is based on a commercially available pyrrolo quinoline quinone (PQQ)-fructose dehydrogenase. The enzyme is introduced into the carbon paste matrix and addition of polyethyleneimine (PEI) allows an unmediated anodic current to be achieved at 400 mV vs. AgAgCl after injections of fructose in the FIA system. Operating at 400 mV, at a flow rate of 1.0 ml min−1 and with 20 μl injection volume, the analytical characteristics of the sensor are: limit of detection 75 μM (S/N 3), linearity up to 10mM, sensitivity 3nA mM−1, complete specificity for fructose and operational stability for 10h. The biosensor-FIA system has been validated by liquid chromatography-refractive index (LC-RI) for the detection of fructose in honey. Results prove the reliability of the biosensor for the quantitation of fructose in honey samples.