Abstract: Anovel renewable liquid drop sensor was proposed for quantitative assay of thiamine based on it′s oxidation by Hg²⁺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^-4to 5.0×10^-3mg/mLthiamine, and with a detection limit of 8.0×10^-4mg/mL. Besides its high sensitivity, the sensor permits a simple, fast, and inexpensive measurement with only micro-quantities reagent consumption.

Key words: Droplet optical chemistry sensor, Thiamine, Fluoremetry