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 system and different data evaluation schemes for isotachophoresis in capillaries is reported. Data acquisition features two channels, automatic range switching and a unique dynamic sampling rate between 0,0125 and 100 Hz which provides compressed data files and smoother signals compared with sampling at a constant rate. Software termed UNIclip was written for data evaluation based on zone length measurements of conductivity and/or UV absorption signals and the chromatographic integration software was employed for data evaluation based on peak areas of baseline-resolved UV absorption peaks. In a configuration with minimized electroosmosis, high-quality data with linear calibration graphs were obtained. In the presence of electroosmosis, and also electroosmosis combined with a vacuum generated co-flow, in principle UV absorbance data with excellent linear calibration and high reproducibility could be obtained. However, the occurrence of outliers and the detection of uneven zone plateaux made accurate quantification difficult using an automated instrument with a single detector placed towards the capillary end.