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Simultaneous determination of lipoic acid (LA) and dihydrolipoic acid (DHLA) in human plasma using high-performance liquid chromatography coupled with electrochemical detection.
MedLine Citation:
PMID:  21550862     Owner:  NLM     Status:  Publisher    
A fast, simple, and a reliable high-performance liquid chromatography linked with electrochemical detector (HPLC-ECD) method for the assessment of lipoic acid (LA) and dihydrolipoic acid (DHLA) in plasma was developed using naproxen sodium as an internal standard (IS) and validated according to standard guidelines. Extraction of both analytes and IS from plasma (250μl) was carried out with a single step liquid-liquid extraction applying dichloromethane. The separated organic layer was dried under stream of nitrogen at 40°C and the residue was reconstituted with the mobile phase. Complete separation of both compounds and IS at 30°C on Discovery HS C18 RP column (250mm×4.6mm, 5μm) was achieved in 9min using acetonitrile: 0.05M phosphate buffer (pH 2.4 adjusted with phosphoric acid) (52:48, v/v) as a mobile phase pumped at flow rate of 1.5mlmin(-1) using electrochemical detector in DC mode at the detector potential of 1.0V. The limit of detection and limit of quantification for lipoic acid were 500pg/ml and 3ng/ml, and for dihydrolipoic acid were 3ng/ml and 10ng/ml, respectively. The absolute recoveries of lipoic acid and dihydrolipoic acid determined on three nominal concentrations were in the range of 93.40-97.06, and 93.00-97.10, respectively. Similarly coefficient of variations (% CV) for both intra-day and inter-day were between 0.829 and 3.097% for lipoic acid and between 1.620 and 5.681% for dihydrolipoic acid, respectively. This validated method was applied for the analysis of lipoic acid/dihydrolipoic acid in the plasma of human volunteers and will be used for the quantification of these compounds in patients with oxidative stress induced pathologies.
Abad Khan; Zafar Iqbal; David G Watson; Amirzada Khan; Inamullah Khan; Naveed Muhammad; Salar Muhammad; Hashmat Ara Nasib; Naveed Iqbal; Faiz-Ur-Rehman; Muhammad Kashif
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-4-22
Journal Detail:
Title:  Journal of chromatography. B, Analytical technologies in the biomedical and life sciences     Volume:  -     ISSN:  1873-376X     ISO Abbreviation:  -     Publication Date:  2011 Apr 
Date Detail:
Created Date:  2011-5-9     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101139554     Medline TA:  J Chromatogr B Analyt Technol Biomed Life Sci     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011 Elsevier B.V. All rights reserved.
Department of Pharmacy, University of Peshawar, Peshawar -25120, Pakistan.
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