Jung Min Lee

Determination of Catechin in Aqueous Solution by Chemiluminescence Method

A method to determine catechin in aqueous solution by measuring chemiluminescence intensities using a stopped flow system has been studied. The lucigenin-hydrogen peroxide chemiluminescence reaction was chosen for the determination of catechin. Fe(II) ion was added to the chemiluminescence system to increase the sensitivity. The chemiluminescence intensity from the lucigenin system was increased by the addition of catechin. Effects of flow rates of reagent and sample and concentrations of lucigenin, hydrogen peroxide, Fe(II) ion and KOH were investigated. The calibration curve for catechin was linear over the range from 1.0×10-3 to 1.0×10-7 M and the detection limit was 3.0×10-7 M under the optimal experimental conditions.

A pH Optosensor Based on Fluoresence from Nile Blue Encapsulated within Silica Sol-Gel Film

A fiber optic pH sensor has been fabricated using nile blue entrapped in an ammonia catalyzed silica sol-gel film coated on glass substrate by dip-coating. The sensor was fixed on the end of an optical fiber. The sensor showed pH sensitivity when dipped into liquids at different pHs. Linear and reproducible responses were obtained in standard buffer solutions in the pH range , which encompasses the clinically-relevant range. The effects of interferences on the determination of pH were also investigated. The sensors were successfully applied to the determination of pH in different commercial ionic drinks.