Off-line FIA monitoring of d-sorbitol consumption during l-sorbose production using a sorbitol biosensor

A ferricyanide mediated amperometric biosensor system implementing d-sorbitol dehydrogenase together with diaphorase for sensitive detection of d-sorbitol was used. The biosensor system was successfully integrated into an off-line FIA system with a throughput of detection of 10 h−1. The device exhibited limit of detection of 20 μM with an average relative standard deviation of analysis of samples of 2.2%. The signal of the biosensor was linear up to 1.1 mM for d-sorbitol with sensitivity of (72 ± 2) nA mM−1, while a dynamic range was much wider up to 18 mM. The sorbitol biosensor gave reliable results even in the presence of a high molar excess of l-sorbose, a product of the biotransformation process, as judged from an excellent agreement with HPLC and GC.