Abstract: Analysis of trace Zn²⁺ by capillary electrophoresis with field-amplified sample stacking(FASS) and high voltage capacitively coupled contactless conductivity detection(C₄D) was presented. 2-(N-Morpholino) ethanesulfonic acid(MES)/histidine(His) was used as the separation electrolyte. The effects of MES/His concentration in the sample matrix, and the injection time on the effective stacking efficiency, and the concentration of the separation electrolyte on the sensitivity were studied. Zn²⁺ was dissolved in deionized water and separated in 10 mmol/L MES/His(pH=4.9) buffer. The C₄D using FASS yielded sensitivity enhancement with respect to non-stacking injection mode in excess of three orders of magnitude(1.3×10³) and a limit of detection(LOD) 5 nmol/L to Zn²⁺. There was a linear relationship between the response of peak area and concentration of Zn²⁺ in the range from 10 to 1 000 nmol/L(R=0.999 5). The method can be used for determination of Zn²⁺ of trace level.

Key words: Capillary electrophoresis, Field-amplified sample injection, Contactless conductivity detection, Zinc ion