Simultaneous determination of stevioside, rebaudioside A and glycyrrhizic acid in foods by HPLC

A method for the simultaneous determination of stevioside (Stev), rebaudioside A (RebA) and glycyrrhizic acid (GA) in foods was developed. These sweeteners were extracted from foods, except for dried fishes and shellfishes, by dialysis against Tris-HCl buffer (pH 9.0). Dried fishes and shellfishes were extracted with Tris-HCl buffer--methanol (2:8). The extracts were cleaned up with an Oasis MAX cartridge. The cartridge was washed with 0.05 mol/L sodium acetate (pH 4.0)--methanol (19:1), and the three sweeteners were eluted with 0.1 mol/L phosphoric acid--acetonitrile (1:1). Stev, RebA and GA in the eluate were chromatographed on a Develosil RPAQUEOUS-AR-5 (4.6 mm i.d. x 250 mm) column with 0.02 mol/L phosphoric acid-acetonitrile--methanol (90:55:5) as a mobile phase and monitored at 210 nm for Stev and RebA, and at 254 nm for GA. The recoveries of Stev, RebA and GA from 8 kinds of foods spiked at the level of 0.1 g/kg were 81.7-101%, 81.5-100% and 78.6-95.0%, respectively. The determination limits were 0.01 g/kg in samples.     

i-Line sensitive photoacid generators for UV curing

UV curing systems based on cationic processes are very significant because the systems have several advantages compared to the radical process. Photoacid generator (PAG) is essential for the cationic UV curing system including epoxides and vinyl ethers. Although many types of PAG have been developed, most of them are not sensitive to i-line (365 nm) from a high-pressure mercury lamp. In this study, non-ionic PAG that is thermally stable and highly sensitive to i-line was designed and synthesized. Imino sulfonate and N-hydroxyimide sulfonate compounds were prepared as PAG. Fluorenone, thioxanthone, and thianthrene skeletons were used as chromophores for PAG. Furthermore, photochemistry of the PAG and its applications to photocrosslinking systems based on epoxy-containing polymers were studied.