| Popis: |
The fundamental definitions of resolution and separability in isotachophoresis are given and extensively discussed. The resolution of a constituent is given as its fractional separated amount and can vary between zero and unity. The steady-state configuration is characterized by resolution values of unity and/or zero and is determined by both the leading electrolyte and the sample. The separability of two constituents depends largely on their physico-chemical characteristics and the time allowed for resolution.The isotachophoretic separation process is elucidated using a transient-state model for monovalent, weakly ionic constituents. The influence of operational parameters, i.e., pH, electrical driving current, sample load and counter constituent, on the separation process is described in terms of resolution time, detection time and load capacity. The efficiency of the separation process is given by the dimensionless separation number.It is shown that optimization procedures are governed by three rationales: the electrical driving current, the common counter constituent and the pH. Of these, only the electrical driving current has no influence on the separation efficiency and load capacity. For anionic separations a low pH of both sample and leading electrolyte favours resolution. When dealing with cationic separations a high pH is preferable. The counter constituent should have a low mobility and the electrical driving current should be maximized. |
