Hydroxyethyliminodiacetic acid in the isotachophoretic separation of alkali cations

N-hydroxyethyliminodiacetic acid (HIDA) has been used for the optimization of the isotachophoretic separation of alkali and alkaline earth metal cations. The required separation effect appears at the leading-electrolyte pH = 6-7. The separation of K+, Na+, Li+, Ba2+, Sr2+, Ca2+, and Mg2+ has been achieved using HIDA as the complexing co-counterion. In the dependence on the leading-electrolyte pH and on the HIDA concentration in it various migration sequences can be achieved in the isotachophoretic steady-state. Alkali metal cations present in the model mixtures were determined in the concentration range (1-125) . 10-5 mol l-1 with the relative standard deviation that was in most cases less than 1%. Detection limits for individual ions (for the injected sample volume of 25μl) were within the limits of (6.4-18). 10-6mol l-1. The separation of the alkali metals in mineral and drinking water and in the lyophilized blood demonstrate the practical use of the agent under study in the ITP analysis