Sweeping via Dynamic Complexation with Cyclohexane-1,2-diaminetetraacetic Acid for Trace Metal Analysis in Capillary Electrophoresis

To improve the detection sensitivity of metal ions in capillary electrophoresis (CE), combination of on-line complexation and sweeping was explored using cyclohexane-1,2-diaminetetraacetic acid (CDTA). CDTA has two roles, as a dynamic complexation agent to form a UV-absorbing complex and a carrier for sweeping. Six metal ions were used as test analytes. The effect of pH, CDTA concentration, composition of BGS and sample matrix, injection length of sample solution were examined and optimized to obtain high performance of this method. Under optimized conditions, the technique was validated in terms of the limit of detection, repeatability, and sensitivity enhancement. Improved detection responses were 60- to 160-fold in terms of peak heights for metal ions in comparison with conventional CZE of precapillary complexed metal ions. The limits of detection were in the range of 0.4 – 4.2 × 10^–7 M.Acknowledgements The authors are thankful to Dr. J.-B. Kim and Miss M.R.N. Monton for their helpful discussions. They are also grateful to Drs. H. Hisamoto and N. Matsubara for their support.