title: Direct enantioseparation of lipoic acid in dietary supplements by capillary electrophoresis using trimethyl-β-cyclodextrin as a chiral selector.
abstract: Lipoic acid, an antioxidant, naturally occurs as the (R)-enantiomer, while synthetic lipoic acid is racemic. It is thus of interest to know the (R)-enantiomer content of lipoic acid supplements. Here, we used capillary electrophoresis to directly enantioseparate lipoic acid in dietary supplements by using a sulfonated capillary with an effective voltage of +18 kV and direct detection at 200 nm. Factors affecting migration time and resolution of lipoic acid were investigated. The optimum background electrolyte was found to be 100 mM phosphate buffer (pH 7.0) containing 8 mM trimethyl-β-cyclodextrin as a chiral selector at 20°C. Under the proposed conditions, direct chiral resolution of lipoic acid in dietary supplements was conducted successfully.
authors.affiliation: Toyama Institute of Health, Toyama, Japan. shuji.kodama@pref.toyama.lg.jp
authors.forename: Shuji
authors.initials: S
authors.lastname: Kodama
authors.forename: Atsushi
authors.initials: A
authors.lastname: Taga
authors.forename: Sen-Ich
authors.initials: SI
authors.lastname: Aizawa
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kemmei
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Honda
authors.forename: Kentaro
authors.initials: K
authors.lastname: Suzuki
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamamoto
mesh_terms: D002214:Capsules / Q000737:chemistry; D019587:Dietary Supplements / Q000032:analysis*; D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D013237:Stereoisomerism; D013607:Tablets / Q000737:chemistry; D008063:Thioctic Acid / Q000737:chemistry* / Q000302:isolation & purification; D047392:beta-Cyclodextrins / Q000737:chemistry*
chemical_list: D002214:Capsules; D013607:Tablets; D047392:beta-Cyclodextrins; D008063:Thioctic Acid