title: Electrokinetic supercharging preconcentration prior to CGE analysis of DNA: sensitivity depends on buffer viscosity and electrode configuration.
abstract: Aiming to high sensitivity DNA analysis by CGE, electrokinetic supercharging (EKS) approach was adopted in this article. EKS is known as an online preconcentration technique that combines electrokinetic sample injection (EKI) with transient ITP (tITP). Herein, two factors of buffer viscosity and electrode configuration were studied to further improve EKS performance. An ultralow-viscosity Tris-Boric acid-EDTA (TBE) buffer solution, consisted of 2% low-molecular-weight hydroxypropyl methyl cellulose (HPMC) and 6% mannitol and with pH 8.0 adjusted by boric acid, was applied. The boric acid would make a complex with mannitol and generates borate polyanion, which acts as the leading ion for tITP process. The new electrode configuration, a Pt ring around capillary, was modified on Agilent CE system to lead large amount sample introduction during EKS. The standard DNA sample of φX174/HaeIII digest was used to evaluate the qualitative and quantitative abilities of the proposed strategy. The 170,000-fold highly diluted sample at concentration of 3.0 ng/mL was enriched by EKS and detected by normal UV detection method. The obtained LOD of the weakest peak of 72 bp fragment was around 7.7 pg/mL, apparently improved more than 10,000-fold in comparison with conventional CGE with UV detection.
authors.affiliation: Applied Chemistry, Department of Chemistry and Chemical Engineering, Graduate School of Engineering, Hiroshima University, Hiroshima, Japan.
authors.forename: Xiaoxue
authors.initials: X
authors.lastname: Ye
authors.forename: Satomi
authors.initials: S
authors.lastname: Mori
authors.forename: Mihoro
authors.initials: M
authors.lastname: Yamada
authors.forename: Junji
authors.initials: J
authors.lastname: Inoue
authors.forename: Zhongqi
authors.initials: Z
authors.lastname: Xu
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hirokawa
mesh_terms: D001435:Bacteriophages / Q000737:chemistry; D001888:Boric Acids / Q000737:chemistry*; D004247:DNA / Q000032:analysis* / Q000737:chemistry; D004492:Edetic Acid / Q000737:chemistry*; D004566:Electrodes; D019075:Electrophoresis, Capillary / Q000295:instrumentation* / Q000379:methods*; D057230:Limit of Detection; D010984:Platinum / Q000737:chemistry; D015203:Reproducibility of Results; D014325:Tromethamine / Q000737:chemistry*; D014783:Viscosity
chemical_list: D001888:Boric Acids; C069591:Tris-borate-EDTA buffer; D014325:Tromethamine; D010984:Platinum; D004247:DNA; D004492:Edetic Acid; C032688:boric acid