title: Determination of ephedrine and pseudoephedrine by field-amplified sample injection capillary electrophoresis.
abstract: A simple and rapid capillary electrophoresis method was developed for the separation and determination of ephedrine (E) and pseudoephedrine (PE) in a buffer solution containing 80 mM of NaH2PO4 (pH 3.0), 15 mM of β-cyclodextrin and 0.3% of hydroxypropyl methylcellulose. The field-amplified sample injection (FASI) technique was applied to the online concentration of the alkaloids. With FASI in the presence of a low conductivity solvent plug (water), an approximately 1,000-fold improvement in sensitivity was achieved without any loss of separation efficiency when compared to conventional sample injection. Under these optimized conditions, a baseline separation of the two analytes was achieved within 16 min and the detection limits for E and PE were 0.7 and 0.6 µg/L, respectively. Without expensive instruments or labeling of the compounds, the limits of detection for E and PE obtained by the proposed method are comparable with (or even lower than) those obtained by capillary electrophoresis laser-induced fluorescence, liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry. The method was validated in terms of precision, linearity and accuracy, and successfully applied for the determination of the two alkaloids in Ephedra herbs.
authors.affiliation: 1Engineering Research Center of Chemical Zero Discharge & Department of Chemical Engineering, Chongqing Industry Polytechnic College, Chongqing 401120, China.
authors.forename: Dongli
authors.initials: D
authors.lastname: Deng
authors.forename: Hao
authors.initials: H
authors.lastname: Deng
authors.forename: Lichun
authors.initials: L
authors.lastname: Zhang
authors.forename: Yingying
authors.initials: Y
authors.lastname: Su
mesh_terms: D019075:Electrophoresis, Capillary / Q000379:methods*; D029790:Ephedra sinica / Q000737:chemistry; D004809:Ephedrine / Q000032:analysis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D016014:Linear Models; D010936:Plant Extracts / Q000737:chemistry*; D054199:Pseudoephedrine / Q000032:analysis* / Q000737:chemistry; D015203:Reproducibility of Results
chemical_list: D010936:Plant Extracts; D054199:Pseudoephedrine; D004809:Ephedrine