Determination of anions from process waters with on-line capillary electrophoresis instrument

Determination of soluble ion concentrations directly in the pulp suspension by separation techniques is needed to control the quality of the final product. The increasing demands for rapid monitoring of samples on-line require either the development of new instruments or the modification of existing commercial instruments. In addition, the analytical methods suitable for rapid on-line analyses must be developed and optimized. Capillary electrophoresis (CE) has demonstrated its potential to become a significant technique for a variety of analyses due to especially its high speed and ease of aytomation. Good results have already been obtained in coupling of the instrument to paper machines. As far we know, no commercial CE instruments exist for totally on-line measurements, though some manufacturers have produced gradient solvent modules compatible with flow cells for change of the samples. In this study, we have developed and tested a short capillary electrophoresis instrument which is suitable for on-line control of industrial processes. The instrument consists of a three partial cell unit, the centre part for the capillary and UV detection. The on-line unit has fixed tunnels for dynamic replenishment of electrolyte solution at its both ends. Due to the on-line solvent delivery system constructed into the CE front and rear positions of the cell unit, the capillary and the platinum electrodes will be kept uncontamined. Samples are introduced into the capillary electrokinetically. Determination of chloride, sulphate, oxalate, formiate and acetate from pulp waters are shown