Simultaneous determination of alpha-lipoic acid and its reduced form by high-performance liquid chromatography with fluorescence detection.
The simultaneous determination of alpha-lipoic acid (LA) and DHLA (reduced form of LA) was carried out by HPLC with fluorescence detection. DHLA in the sample was first labeled with ABD-F at room temperature for 10 min and then the LA was labeled with SBD-F at 50 degrees C for 1 h after conversion to DHLA using the reducing agent, TCEP. The resulting fluorophores, ABD-DHLA and SBD-DHLA, were separated by reversed-phase chromatography and detected at 510 nm (excitation at 380 nm). Both fluorophors were completely separated without any interference of endogenous thiols and disulfides in the sample and sensitively detected by fluorimetry. The proposed method was applied to the assay of the LA supplement and the determination in human plasma after the oral administration of LA tablets. The concentration (%) of LA in the tablet was reasonable to the stated amount. Furthermore, the result of a time course study in the plasma after the administration of LA did not differ from a previous report. Thus, the present method seems to be applicable to the simultaneous determination of LA and DHLA in various biological specimens.
Satoh
Soichiro
S
Division of Bio-Analytical Chemistry, School of Pharmaceutical Sciences, and COE Program in the 21st Century, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
Toyo'oka
Toshimasa
T
Fukushima
Takeshi
T
Inagaki
Shinsuke
S
D000328:Adult; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D008297:Male; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013607:Tablets / Q000737:chemistry; D008063:Thioctic Acid / Q000032:analysis* / Q000097:blood
D013607:Tablets; D008063:Thioctic Acid