title: Comparison of the use of single capillaries and coupled capillaries based on micellar electrokinetic chromatography (MEKC) and sweeping-MEKC modes.
abstract: The use of single capillaries (25 and 50 microm inner diameter (ID)) and coupled capillaries of different diameters (100-50 and 75-25 microm ID) based on micellar electrokinetic chromatography (MEKC) and sweeping-MEKC modes is compared and reported. Naphthalene-2,3-dicarboxaldehyde (NDA)-derivatized dopamine was selected as the model compound by examining the fluorescence intensity when a violet (410 +/- 7 nm, 2 mW) light-emitting-diode (LED) was used as the light source. When a single capillary (50 microm ID) was used, the detection limit for NDA-derivatized dopamine was determined to be 2.0 x 10(-7) M (Signal-to-nose ratio S/N = 3) based on the MEKC mode. This was improved to 4.0 x 10(-9) M when the sweeping-MEKC mode was applied. In addition, this can be further improved to 1.0 x 10(-9) M and 5.6 x 10(-10) M when 100-50 and 75-25 microm ID coupled capillaries are used. The use of the coupled capillary is also helpful for improving the separation efficiency. Based on the sweeping-MEKC mode, the number of theoretical plates (N) for the detected peaks were determined to be 6.3 +/- 2.7 x 10(5) by means of a single capillary (50 microm ID). This can be improved to 9.4 +/- 3.6 x 10(5) and 9.4 +/- 0.9 x 10(6) when the 100-50 and 75-25 microm ID coupled capillaries were applied.
authors.affiliation: Department of Chemistry, National Taiwan Normal University, Taipei, Taiwan.
authors.forename: Chun-Min
authors.initials: CM
authors.lastname: Shih
authors.affiliation: Department of Chemistry, National Taiwan Normal University, Taipei, Taiwan.
authors.forename: Cheng-Huang
authors.initials: CH
authors.lastname: Lin
mesh_terms: D020374:Chromatography, Micellar Electrokinetic Capillary / Q000295:instrumentation* / Q000379:methods*; D004298:Dopamine / Q000031:analogs & derivatives / Q000302:isolation & purification; D019075:Electrophoresis, Capillary / Q000379:methods; D009281:Naphthalenes / Q000737:chemistry; D012967:Sodium Dodecyl Sulfate; D013050:Spectrometry, Fluorescence
chemical_list: D009281:Naphthalenes; D012967:Sodium Dodecyl Sulfate; C027717:2,3-naphthalenedicarboxaldehyde; D004298:Dopamine