Running buffers for determination of chromium(VI)/(III), cobalt(II) and zinc(II) in complex matrices by capillary electrophoresis with contactless conductivity detection.
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.
Wang
Li-Shi
LS
College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510640, PR China.
Zhang
Shui-Feng
SF
Dang
Zhi
Z
Liu
Xiao-Xiao
XX
Huang
Xin-Jian
XJ
Xiao
Ming-Wei
MW
Chen
Zuan-Guang
ZG