Electro membrane extraction combined with capillary electrophoresis for the determination of amlodipine enantiomers in biological samples.

Electro membrane extraction as a new microextraction method was applied for the extraction of amlodipine (AM) enantiomers from biological samples. During the extraction time of 15  min, AM enantiomers migrated from a 3  mL sample solution, through a supported liquid membrane into a 20  μL acceptor solution presented inside the lumen of the hollow fiber. The driving force of the extraction was 200  V potential, with the negative electrode in the acceptor solution and the positive electrode in the sample solution. 2-Nitro phenyl octylether was used as the supported liquid membrane. Using 10  mM HCl as background electrolyte in the sample and acceptor solution, enrichment up to 124 times was achieved. Then, the extract was analyzed using CD modified CE method for separation of AM enantiomers. Best results were achieved using a phosphate running buffer (100  mM, pH 2.0) containing 5  mM hydroxypropyl-α-CD. The range of quantitation for both enantiomers was 10-500  ng/mL. Intra- and interday RSD (n=6) were less than 14%. The limits of quantitation and detection for both enantiomers were 10 and 3  ng/mL respectively. Finally, this procedure was applied to determine the concentration of AM enantiomers in plasma and urine samples.