caa a22 4500 445802820 CHVBK 20180317145146.0 cr unu---uuuuu 170323e20110501xx s 000 0 eng 10.1007/s10337-011-1997-3 doi (NATIONALLICENCE)springer-10.1007/s10337-011-1997-3 Simultaneous Determination of the Endogenous Free α-Lipoic Acid and Dihydrolipoic Acid in Human Plasma and Erythrocytes by RP-HPLC with Electrochemical Detection [Elektronische Daten] [Muhammad Khan, Zafar Iqbal, Lateef Ahmad, Yasar Shah, Shabnam Nazir, Abbas Khan, Fazli Nasir] A highly sensitive, precise, and accurate reversed-phase high-performance liquid-chromatography/electrochemical detection method for simultaneous determination of the endogenous free α-lipoic acid and dihydrolipoic acid in biological matrices was developed and validated. The two analytes were extracted from the samples with acetonitrile/10% metaphosphoric acid solution(aqueous) (50/50 v/v). To determine the total lipoic acid, samples were treated with tris(2-carboxyethyl)phosphine solution in phosphate buffer, pH 2.5 with 85% orthophosphoric acid prior to deproteination. The two analytes were separated on a C18 (150×4.6mm, 5μm) analytical column using acetonitrile-50mM phosphate buffer, pH 2.5 with 85% orthophosphoric acid (35/65 v/v) as the isocratic mobile phase pumped at a flow rate of 2.0mLmin−1 at the column oven temperature of 35°C. The column eluents were monitored at a potential of 0.9V. These analytes were efficiently resolved in <7min. The present method was sufficiently robust and specific for simultaneous determination of the two analytes and demonstrated acceptable values for linearity (r 2=0.999 in the range of 0.1-500 and 0.25-1,000ngmL−1 for α-lipoic acid and dihydrolipoic acid, respectively), recovery (>97%), precision (RSD%<2), and sensitivity (on column limit of detection, 150 and 375fg for α-lipoic acid and dihydrolipoic acid, respectively and limit of quantification: 0.5 and 1.25pg for α-lipoic acid and dihydrolipoic acid, respectively), indicating that the proposed method was more sensitive, precise, economical, and versatile, and has higher throughput than the previously reported methods for simultaneous determination of the two analytes. Springer-Verlag, 2011 Column liquid chromatography nationallicence α-Lipoic acid nationallicence Dihydrolipoic acid nationallicence Validation nationallicence Optimization nationallicence Electrochemical detection nationallicence Khan Muhammad Department of Pharmacy, University of Peshawar, 25120, Peshawar, Pakistan aut Iqbal Zafar Department of Pharmacy, University of Peshawar, 25120, Peshawar, Pakistan aut Ahmad Lateef Department of Pharmacy, University of Peshawar, 25120, Peshawar, Pakistan aut Shah Yasar Department of Pharmacy, University of Peshawar, 25120, Peshawar, Pakistan aut Nazir Shabnam Department of Pharmacy, University of Peshawar, 25120, Peshawar, Pakistan aut Khan Abbas Department of Pharmacy, University of Peshawar, 25120, Peshawar, Pakistan aut Nasir Fazli Department of Pharmacy, University of Peshawar, 25120, Peshawar, Pakistan aut Chromatographia Springer-Verlag 73/9-10(2011-05-01), 929-939 0009-5893 73:9-10<929 2011 73 10337 https://doi.org/10.1007/s10337-011-1997-3 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10337-011-1997-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Khan Muhammad Department of Pharmacy, University of Peshawar, 25120, Peshawar, Pakistan aut NATIONALLICENCE 700 1- Iqbal Zafar Department of Pharmacy, University of Peshawar, 25120, Peshawar, Pakistan aut NATIONALLICENCE 700 1- Ahmad Lateef Department of Pharmacy, University of Peshawar, 25120, Peshawar, Pakistan aut NATIONALLICENCE 700 1- Shah Yasar Department of Pharmacy, University of Peshawar, 25120, Peshawar, Pakistan aut NATIONALLICENCE 700 1- Nazir Shabnam Department of Pharmacy, University of Peshawar, 25120, Peshawar, Pakistan aut NATIONALLICENCE 700 1- Khan Abbas Department of Pharmacy, University of Peshawar, 25120, Peshawar, Pakistan aut NATIONALLICENCE 700 1- Nasir Fazli Department of Pharmacy, University of Peshawar, 25120, Peshawar, Pakistan aut NATIONALLICENCE 773 0- Chromatographia Springer-Verlag 73/9-10(2011-05-01), 929-939 0009-5893 73:9-10<929 2011 73 10337 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer