Co/Al layered double hydroxide coated electrode for in flow amperometric detection of sugars

This work reports the development and application of a device for the amperometric detection of sugars in flow systems, based on the electrochemical deposition of a Co/Al layered double hydroxide (LDH) on a Pt electrode. A good adhesion of the LDH film on the metal surface was proved with a bending test which did not display areas in which peeling had taken place. The response of the sensor is based on the analytes oxidation catalysed by the Co(IV) centres of the LDH layers. The efficiency of the catalytic Co centres was studied in solutions with different pHs from 10 to 12.8. The highest sensitivity and the lowest LOD for the investigated sugars were obtained when the most basic solution was employed. The most important mono- and di-saccharides were analysed by flow injection analysis and a mixture was submitted to high performance anion chromatography with amperometric detection, using the developed device as the working electrode. To assess the applicability of the device glucose, fructose, and sucrose content in real samples of cereals and tea drink was successfully determined.