Home
Resources
Publications
Dispersive Liquid-Liquid Microextraction Combined With Microwave-Assisted Derivatization for Determining Lipoic Acid and Its Metabolites in Human Urine

Dispersive Liquid-Liquid Microextraction Combined With Microwave-Assisted Derivatization for Determining Lipoic Acid and Its Metabolites in Human Urine

Chia-Ju Tsai, Yen-Ling Chen, Chia-Hsien Feng

J Chromatogr A. 2013 Oct 4;1310:31-6.

PMID: 23993748

Abstract:

This study explored dispersive liquid-liquid microextraction for extraction and concentration of lipoic acid in human urine. To improve the detection of lipoic acid by both capillary liquid chromatography (CapLC) with UV detection and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), microwave-assisted derivatization with 4-bromomethyl-6,7-dimethoxycoumarin was performed to render lipoic acid chromophores for UV detection and also high ionization efficiency in MALDI. All parameters that affected lipoic acid extraction and derivatization from urine were investigated and optimized. In the analyses of human urine samples, the two methods had a linear range of 0.1-20 μM with a correlation coefficient of 0.999. The detection limits of CapLC-UV and MALDI-TOF MS were 0.03 and 0.02 μM (S/N ≧ 3), respectively. The major metabolites of lipoic acid, including 6,8-bismethylthio-octanoic acid, 4,6-bismethylthio-hexanoic acid, and 2,4-bismethylthio-butanoic acid were also extracted by dispersive liquid-liquid microextraction and detected by MALDI-TOF MS. The minor metabolites (undetectable by MALDI-TOF MS), bisnorlipoic acid and tetranorlipoic acid were also extracted by dispersive liquid-liquid microextraction and identified with an LTQ Orbitrap mass spectrometer. After dispersive liquid-liquid microextraction and microwave-assisted derivatization, all lipoic acid derivatizations and metabolites were structurally confirmed by LTQ Orbitrap.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP88404255	4-Bromomethyl-6,7-dimethoxycoumarin		88404-25-5	Price

As a specialist in analytical chemical Products, Alfa Chemistry offers consumers a wealth of raw materials and a full range of technologies and services.

QUICK LINKS

HEADQUARTERS

Tel:

Fax:

Email: