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, Ag/AgCl 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 mu l injection volume, the analytical characteristics of the sensor are: limit of detection 75 mu M (S/N 3), linearity up to 10 mM, sensitivity 3 nA mM(-1), complete specificity for fructose and operational stability for 10 h. 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.