title: EOF measurement by detection of a sampling zone with end-channel amperometry in microchip CE.
abstract: A simple method for EOF measurement by detection of sampling zones with end-channel amperometry in microchip CE is developed. This method is based on the principle of the Kohlrausch regulating function (KRF). A dilute electroactive ionic species is added to the BGE as a continuously eluting electrophore which is used as a probe. When a BGE-like sample at a different concentration is injected, a peak of sampling zone appears and the migration time is related to EOF. In a microchip CE with hybrid PDMS/glass channel, a cathodic EOF of the hybrid glass/PDMS microchip was measured by end-channel amperometry; the effects of sample concentration and different probes on EOF rate were discussed. The present method was applied to monitor EOF rates in glass and in PDMS microchips. There was no significant difference between the values of EOF rates measured by the present method and the current-monitoring method. Detection of nonelectroactive analytes K(+), Na(+), and Li(+) can also be accomplished by the indirect amperometric method. Hence, the effective mobility of analyte can be accurately obtained.
authors.affiliation: Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Liang
authors.initials: L
authors.lastname: Zhao
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Jiang
authors.forename: Jian-Rong
authors.initials: JR
authors.lastname: Zhang
authors.forename: Jun-Jie
authors.initials: JJ
authors.lastname: Zhu
authors.forename: Hong-Yuan
authors.initials: HY
authors.lastname: Chen
mesh_terms: D003217:Conductometry; D053841:Electroosmosis; D019075:Electrophoresis, Capillary / Q000379:methods*; D046209:Electrophoresis, Microchip / Q000379:methods*