EFFICIENT COMPUTERIZED DATA-ACQUISITION AND EVALUATION FOR CAPILLARY ISOTACHOPHORESIS IN QUIESCENT AND FLOWING SOLUTION WITH SINGLE DETECTORS PLACED TOWARDS THE CAPILLARY END

The use of a commercial, inexpensive, computerized data acquisition sy stem and different data evaluation schemes for isotachophoresis in cap illaries is reported. Data acquisition features two channels, automati c range switching and a unique dynamic sampling rate between 0,0125 an d 100 Hz which provides compressed data files and smoother signals com pared with sampling at a constant rate. Software termed UNIclip was wr itten for data evaluation based on zone length measurements of conduct ivity and/or UV absorption signals and the chromatographic integration software was employed for data evaluation based on peak areas of base line-resolved UV absorption peaks. In a configuration with minimized e lectroosmosis, high-quality data with linear calibration graphs were o btained. In the presence of electroosmosis, and also electroosmosis co mbined with a vacuum generated co-flow, in principle UV absorbance dat a with excellent linear calibration and high reproducibility could be obtained. However, the occurrence of outliers and the detection of une ven zone plateaux made accurate quantification difficult using an auto mated instrument with a single detector placed towards the capillary e nd.