title: The use of ethylene glycol solution as the running buffer for highly efficient microchip-based electrophoresis in unmodified cyclic olefin copolymer microchips.
abstract: An ethylene glycol solution was used as the electrophoretic running buffer in unmodified cyclic olefin copolymer (COC) microchips to minimize the interactions between the analytes and the hydrophobic walls of the plastic microchannels, enhance the resolution of the analytes and eliminate the uncontrollable dispersion caused by uneven liquid levels and non-uniform surfaces of the separation channels. Five amino acids that were labeled with fluorescein isothiocyanate (FITC) were used as model analytes to examine the separation efficiency. The effects of ethylene glycol concentration, pH and sodium tetraborate concentration were systematically investigated. The five FITC-labeled amino acids were effectively resolved using a COC microchip with an effective length of 2.5 cm under optimum conditions, which included using a running buffer of 20 mmol/L sodium tetraborate in ethylene glycol:water (80:20, v/v), pH 6.7. A theoretical plate number of 4.8 × 10(5)/m was obtained for aspartic acid. The system exhibited good repeatability, and the relative standard deviations (n=5) of the peak areas and migration times were no more than 3.4% and 0.7%, respectively. Furthermore, the system was successfully applied to elucidate these five amino acids in human saliva.
authors.affiliation: Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization, Gansu Province, Sate Key Laboratory of Applied Organic Chemistry, Department of Chemistry, Lanzhou University, 222 Southern Tianshui Road, Lanzhou, Gansu 730000, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Hui
authors.initials: H
authors.lastname: Ding
authors.forename: Jing
authors.initials: J
authors.lastname: Wu
authors.forename: Lili
authors.initials: L
authors.lastname: Wang
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.forename: Qiaosheng
authors.initials: Q
authors.lastname: Pu
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001881:Borates; D003516:Cycloparaffins / Q000737:chemistry*; D046209:Electrophoresis, Microchip / Q000295:instrumentation* / Q000379:methods*; D019855:Ethylene Glycol / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D016014:Linear Models; D015203:Reproducibility of Results; D012463:Saliva / Q000737:chemistry
chemical_list: D000596:Amino Acids; D001881:Borates; D003516:Cycloparaffins; C010634:sodium borate; D019855:Ethylene Glycol