Determination of dopamine and norepinephrine in Portulaca oleracea L. by micellar electrokinetic capillary chromatography with amperometric detection
Weng, Q.; Yuan, K.; Zhang, H.; Xiong, J.; Wang, C.; Xu, G.
Se Pu 23(1): 18-21
2005
ISSN/ISBN: 1000-8713 PMID: 15881360 Document Number: 589817
A method based on micellar electrokinetic capillary chromatography with electrochemical detection (MEKC-EC) was developed for the simultaneous determination of norepinephrine (NE) and dopamine (DA) in Chinese herbal plant extracts of Portulaca oleracea L. The effects of several factors such as the acidity and concentration of running buffer, sodium dodecylsulfate (SDS) concentration and detection potential were investigated to acquire the optimum conditions. The two analytes could be well separated within 12 min in a 64 cm capillary at the separation voltage of 25 kV in a 10 mmol/L phosphate buffer (pH 6.23) containing 10 mmol/L SDS. The excellent linearity was obtained in the concentration range from 1.0 x 10(-6) to 5.0 x 10(-4) mol/L. The detection limits of concentration were 4.2 x 10(-7) mol/L for NE and 8.7 x 10(-7) mol/L for DA and those of quantity were 0.41 fmol for NE and 1.45 fmol for DA at a signal-to-noise ratio of 3. This method was successfully used in the analysis of Portulaca oleracea L. without derivatization procedure, and real average contents of NE and DA in Portulaca oleracea L. were 0.015% and 0.20%, respectively.