EFFECT OF SAMPLE COMPOSITION ON THE SEPARATION EFFICIENCY OF ISOTACHOPHORESIS

In order to clarify the effect of the sample composition on the separation efficiency of isotachophoresis, approximate equations expressing the resolution time of strong electrolytes were derived. The transient two-component mixed zone formed in the separation process of a three-component mixture was simulated by varying the molar amount and the mobility of the third component. It was apparent that the resolution time of two components of interest was increased with the addition of the other components, owing to the change in the potential gradient of the two-component mixed zone. The magnitude of the delay was especially large when the mobility of the added component was close to that of the two components of interest. The increase in resolution time was evaluated for the separation of mixtures of up to six equimolar components. The present simulation was confirmed by analysing the actual separation process using a scanning ultraviolet spectrophotometric detector.