title: Running buffers for determination of chromium(VI)/(III), cobalt(II) and zinc(II) in complex matrices by capillary electrophoresis with contactless conductivity detection.
abstract: Complex matrices and rather high acidity in environmental samples are often the impelling challenges for the used running buffers of capillary electrophoresis. Twelve binary acid-base buffers were evaluated for separation of Cr(VI)/Cr(III), Co(2+) and Zn(2+) in a sample containing various salts by capillary electrophoresis with contactless conductivity detector. The malic acid (MA) systems including MA-His (histidine), MA-Arg (arginine) and MA-Tris (tris(hydroxymethyl)aminomethane) were selected as the candidates with powerful separation efficiency and good response sensitivity. In the MA-Tris buffer, optimization were further carried out in terms of the pH value and the concentration of MA, and the optimal conditions were obtained as 6mM MA-Tris and 2mM 18-crown-6 at pH 3.5. Furthermore, a real application was demonstrated by analyzing the plating rinse water (pH 0.8), in which the Ca(2+), Na(+), Cr(VI)/Cr(III), Co(2+) and Zn(2+) were all detected by adjusting at pH 3.5 with 5% (v/v) diluent ammonia. Both the cations, e.g., K(+), Ca(2+), Na(+), Mg(2+), and the common high concentration anions in the sample, e.g., Cl(-), SO(4)(2-) and NO(3)(-) did not cause any disturbance to the concerned analytes.
authors.affiliation: College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510640, PR China.
authors.forename: Li-Shi
authors.initials: LS
authors.lastname: Wang
authors.forename: Shui-Feng
authors.initials: SF
authors.lastname: Zhang
authors.forename: Zhi
authors.initials: Z
authors.lastname: Dang
authors.forename: Xiao-Xiao
authors.initials: XX
authors.lastname: Liu
authors.forename: Xin-Jian
authors.initials: XJ
authors.lastname: Huang
authors.forename: Ming-Wei
authors.initials: MW
authors.lastname: Xiao
authors.forename: Zuan-Guang
authors.initials: ZG
authors.lastname: Chen