Abstract
A rapid, inexpensive, sensitive and specific HPLC-ECD method for the determination of lipoic acid in human plasma was developed and validated over the linearity range of 0.001-10 mu g/ml using naproxen sodium as an internal standard (IS). Extraction of lipoic acid and IS from plasma (250 mu l) was carried out with a simple one step liquid-liquid extraction using dichloromethane. Similarly solid-phase extraction was carried out using dichloromethane as extraction solvent. The separated organic layer was dried under the stream of nitrogen at 40 degrees C and the residue was reconstituted with the mobile phase. Complete separation of both lipoic acid and IS at 30 degrees C on Discovery HS C18 RP column (250 mm x 4.6 mm, 5 mu m) was achieved in 6 min using 0.05 M phosphate buffer (pH 2.5 adjusted with phosphoric acid):acetonitrile (50:50, v/v) as a mobile phase pumped at the rate of 1.5 ml/min using electrochemical detector in DC mode at the detector potential of 1.0 V. The limit of detection and limit of quantification of lipoic acid were 200 pg/ml and 1 ng/ml, respectively. While on column limit of detection and limit of quantification of lipoic acid were 10 and 50 pg/ml, respectively. The absolute recoveries of lipoic acid with liquid-liquid and solid-phase extraction were 98.43, 95.65, 101.45, and 97.36, 102.73, 100.17% at 0.5, 1 and 5 mu g/ml levels, respectively. Coefficient of variations for both intra-day and inter-day were between 0.28 and 4.97%. The method is validated and will be quite suitable for the analysis of lipoic acid in the plasma of human volunteers as well as patients with diabetes and cardiovascular diseases. (C) 2010 Elsevier B.V. All rights reserved.
| Language | English |
|---|---|
| Pages | 2782-2788 |
| Number of pages | 7 |
| Journal | Journal of Chromatography B |
| Volume | 878 |
| Issue number | 28 |
| DOIs | |
| Publication status | Published - 15 Oct 2010 |
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Keywords
- human plasma
- solid-phase extraction
- lipoic acid
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Determination of lipoic acid in human plasma by HPLC-ECD using liquid-liquid and solid-phase extraction: method development, validation and optimization of experimental parameters. / Khan, Abad; Khan, Muhammad I.; Iqbal, Zafar; Ahmad, Lateef; Shah, Yasar; Watson, David G.
In: Journal of Chromatography B, Vol. 878, No. 28, 15.10.2010, p. 2782-2788.Research output: Contribution to journal › Article
TY - JOUR
T1 - Determination of lipoic acid in human plasma by HPLC-ECD using liquid-liquid and solid-phase extraction: method development, validation and optimization of experimental parameters
AU - Khan, Abad
AU - Khan, Muhammad I.
AU - Iqbal, Zafar
AU - Ahmad, Lateef
AU - Shah, Yasar
AU - Watson, David G.
PY - 2010/10/15
Y1 - 2010/10/15
N2 - A rapid, inexpensive, sensitive and specific HPLC-ECD method for the determination of lipoic acid in human plasma was developed and validated over the linearity range of 0.001-10 mu g/ml using naproxen sodium as an internal standard (IS). Extraction of lipoic acid and IS from plasma (250 mu l) was carried out with a simple one step liquid-liquid extraction using dichloromethane. Similarly solid-phase extraction was carried out using dichloromethane as extraction solvent. The separated organic layer was dried under the stream of nitrogen at 40 degrees C and the residue was reconstituted with the mobile phase. Complete separation of both lipoic acid and IS at 30 degrees C on Discovery HS C18 RP column (250 mm x 4.6 mm, 5 mu m) was achieved in 6 min using 0.05 M phosphate buffer (pH 2.5 adjusted with phosphoric acid):acetonitrile (50:50, v/v) as a mobile phase pumped at the rate of 1.5 ml/min using electrochemical detector in DC mode at the detector potential of 1.0 V. The limit of detection and limit of quantification of lipoic acid were 200 pg/ml and 1 ng/ml, respectively. While on column limit of detection and limit of quantification of lipoic acid were 10 and 50 pg/ml, respectively. The absolute recoveries of lipoic acid with liquid-liquid and solid-phase extraction were 98.43, 95.65, 101.45, and 97.36, 102.73, 100.17% at 0.5, 1 and 5 mu g/ml levels, respectively. Coefficient of variations for both intra-day and inter-day were between 0.28 and 4.97%. The method is validated and will be quite suitable for the analysis of lipoic acid in the plasma of human volunteers as well as patients with diabetes and cardiovascular diseases. (C) 2010 Elsevier B.V. All rights reserved.
AB - A rapid, inexpensive, sensitive and specific HPLC-ECD method for the determination of lipoic acid in human plasma was developed and validated over the linearity range of 0.001-10 mu g/ml using naproxen sodium as an internal standard (IS). Extraction of lipoic acid and IS from plasma (250 mu l) was carried out with a simple one step liquid-liquid extraction using dichloromethane. Similarly solid-phase extraction was carried out using dichloromethane as extraction solvent. The separated organic layer was dried under the stream of nitrogen at 40 degrees C and the residue was reconstituted with the mobile phase. Complete separation of both lipoic acid and IS at 30 degrees C on Discovery HS C18 RP column (250 mm x 4.6 mm, 5 mu m) was achieved in 6 min using 0.05 M phosphate buffer (pH 2.5 adjusted with phosphoric acid):acetonitrile (50:50, v/v) as a mobile phase pumped at the rate of 1.5 ml/min using electrochemical detector in DC mode at the detector potential of 1.0 V. The limit of detection and limit of quantification of lipoic acid were 200 pg/ml and 1 ng/ml, respectively. While on column limit of detection and limit of quantification of lipoic acid were 10 and 50 pg/ml, respectively. The absolute recoveries of lipoic acid with liquid-liquid and solid-phase extraction were 98.43, 95.65, 101.45, and 97.36, 102.73, 100.17% at 0.5, 1 and 5 mu g/ml levels, respectively. Coefficient of variations for both intra-day and inter-day were between 0.28 and 4.97%. The method is validated and will be quite suitable for the analysis of lipoic acid in the plasma of human volunteers as well as patients with diabetes and cardiovascular diseases. (C) 2010 Elsevier B.V. All rights reserved.
KW - human plasma
KW - solid-phase extraction
KW - lipoic acid
UR - http://www.scopus.com/inward/record.url?scp=77957312456&partnerID=8YFLogxK
U2 - 10.1016/j.jchromb.2010.08.022
DO - 10.1016/j.jchromb.2010.08.022
M3 - Article
VL - 878
SP - 2782
EP - 2788
JO - Journal of Chromatography B
T2 - Journal of Chromatography B
JF - Journal of Chromatography B
SN - 1570-0232
IS - 28
ER -