Determination of heavy metals by isotachophoresis.

The suitability of isotachophoresis for the analysis of metals in, e.g., environmental samples was studied. In a cationic operational system the heavy metals Fe, Cu, Ni, Cd, Co, Zn, Pb and Mn were simultaneously determined. The separation was achieved through complex formation with one of the counter ions, hydroxyisobutyric acid. The other counter ion was acetic acid, the leading ion was 0.02 M potassium or sodium (pH 4.1) and the terminator was H+. The analysis time was 15 min at 60 microA in a 0.2 mm I.D. capillary. Aqueous samples containing ppm and ppb amounts were enriched on a cation exchanger with an extremely low affinity for sodium (Chelex 100). Good recovery, linearity, precision and accuracy were obtained even down to the ppb range. Although the sensitivity of the method is not greater than that of some of the more established methods for the individual metals, a great advantage of isotachophoresis is the simultaneous determination of the metals, with equal response factors. An example is given of the determination of metals, including aluminium, in serum.