Optical chemical sensing of pH and water content in organic solvents is proposed, using multiinformation dyes (MIDs) based on the support matrixes for the dyes. In this investigation, four kinds of merocyanine-type dyes having a polymerizable olefin unit as the MIDs were synthesized. These dyes were copolymerized with hydrophilic monomer molecules to obtain dye-immobilized optical chemical sensor (optode) membranes. In this case, selection of the monomer molecule gave optode membranes having different color change properties, because different monomer molecules provided different chemical environments around the immobilized dye. These optode membranes were used for the measurement of pH and water content in organic solvents. These membranes offered two-dimensional sensing information in one spectrum when they were employed for water content sensing in organic solvents, in which the maximum wavelength represents the water content and the absorbance at this wavelength represents the pH of the water present. These polymer membranes have a long lifetime, which can be adequate for practical use.

Cyclodextrin-modified micellar electrokinetic chromatography was applied to the enantioseparation of catechin and epicatechin using 6-O-alpha-D-glucosyl-beta-cyclodextrin together with sodium dodecyl sulfate and borate-phosphate buffer. Factors affecting chiral resolution and migration time of catechin and epicatechin were studied. The optimum running conditions were found to be 200 mM borate-20 mM phosphate buffer (pH 6.4) containing 25 mM 6-O-alpha-D-glucosyl-beta-cyclodextrin and 240 mM sodium dodecyl sulfate with an effective voltage of +25 kV at 20 degrees C using direct detection at 210 nm. Under these conditions, the resolution (Rs) of racemic catechin and epicatechin were 4.15 and 1.92, respectively. With this system, catechin and epicatechin enantiomers along with other four catechins ((-)-catechin gallate, (-)-epicatechin gallate, (-)-epigallocatechin, (-)-epigallocatechin gallate) and caffeine in tea samples were analyzed successfully. The difference of migration time between catechin and epicatechin is discussed.

Enantiomeric separation and detection of D,L‐aspartic acid (Asp) derivatized with 4‐fluoro‐7‐nitro‐2,1,3‐benzoxadiazole (NBD‐F) by capillary electrophoresis (CE) using modified cyclodextrins as chiral selectors was studied. Heptakis(2,3,6‐tri‐O‐methyl)‐β‐cyclodextrin(TM‐β‐CD) was most effective for enantiomeric separation of NBD‐D,L‐Asp with optimum conditions of 30 mM TM‐β‐CD in 50 mM phosphate buffer (pH 4.0) and the limit of detection (LOD) attained was 100 nM for each enantiomer. The method proposed in the present study was convenient for both D‐ and L‐Asp determination since the other amino compounds migrated differently and D‐Asp in bio‐samples such as rat pineal gland and foods was determined with a simple sample pretreatment and a short analysis run time. Copyright © 1999 John Wiley & Sons, Ltd.

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Enantiomeric separation and detection of D,L-aspartic acid (Asp) derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) by capillary electrophoresis (CE) using modified cyclodextrins as chiral selectors was studied. Heptakis(2,3, 6-tri-O-methyl)-beta-cyclodextrin(TM-beta-CD) was most effective for enantiomeric separation of NBD-D,L-Asp with optimum conditions of 30 mM TM-beta-CD in 50 mM phosphate buffer (pH 4.0) and the limit of detection (LOD) attained was 100 nM for each enantiomer. The method proposed in the present study was convenient for both D- and L-Asp determination since the other amino compounds migrated differently and D-Asp in bio-samples such as rat pineal gland and foods was determined with a simple sample pretreatment and a short analysis run time.