An effective and fast method for assay of micro-amounts of glucose was set up. A new technique for preparation of enzyme columns based on enzyme immobilization by sol-gel was investigated. Glucose oxidase(GOD) and horseradish peroxidase(HRP) mixed with SiO 2 nanoparticles and polyvinyl butyral(PVB) medium were immobilized on the surface of capillary tube, respectively. The experimental results show that nanoparticles can significantly enhance the catalytic activity of immobilized enzyme. Based on GOD column and HRP column, a liquid droplet sensor was developed for the determination of glucose solution. The effect of separated columns and mixed columns on the response of glucose sensor was investigated. The sensor showed a linear response in a range of 2-400 ng/mL with a detection limit of 0.3 ng/mL under the optimum conditions. The characteristics of the sensor including effect of flow-rate, pH and temperature were discussed.
A novel renewable liquid drop sensor was proposed for quantitative assay of thiamine based on it′s oxidation by Hg 2+ in basic medium. The dynamically growing and falling drops formed at the end of a silanized silica capillary tube served as the reactors for a chromogenic reaction and windowless optical cells as well. The optimum analytical conditions have been established. The sensor showed a linear response in the measuring range from 1.0×10 -4 to 5.0×10 -3 mg/mL thiamine, and with a detection limit of 8.0×10 -4 mg/mL. Besides its high sensitivity, the sensor permits a simple, fast, and inexpensive measurement with only micro-quantities reagent consumption.
