Enantioselective high-performance liquid chromatography assay of (+)R- and (-)S-alpha-lipoic acid in human plasma.
A specific plasma level assay for the enantiomers of alpha-lipoic acid is described. It makes use of liquid-liquid extraction, chemical reduction to the dithiol enantiomers, and their precolumn chiral derivatisation with o-phthalaldehyde in the presence of D-phenylalanine. The two diastereomeric derivatives are separated by reversed-phase HPLC with fluorescence detection. The working range of the assay is between 15 ng/ml (lower limit of quantitation) and 1,000 ng/ml for either enantiomer.
Niebch
G
G
Department of Biochemistry, ASTA Medica AG, Frankfurt, Germany.
Büchele
B
B
Blome
J
J
Grieb
S
S
Brandt
G
G
Kampa
P
P
Raffel
H H
HH
Locher
M
M
Borbe
H O
HO
Nubert
I
I
Fleischhauer
I
I
D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006801:Humans; D012015:Reference Standards; D013050:Spectrometry, Fluorescence; D013237:Stereoisomerism; D008063:Thioctic Acid / Q000097:blood*
D008063:Thioctic Acid