Cleaning-up dirty isotachopherograms in time and frequency domain

In chromatography and electrophoresis S/N is increased by time or frequency domain filtering, multiple injections or sample stacking (in case of CZE). Bottom line is noise reduction without peak distortion. Isotachophoresis (ITP) using conductivity detection is also relevant because of its entirely different information content and the importance in CZE stacking. Several time- and frequency domain filters (Fourier & Walsh transform) were compared. Results were: • Time domain filters can be equally applied to either integral or differential signal; • Fourier and Walsh transforms are likewise suitable, whereas Walsh better preserves sharp boundaries; • Disturbance by detector transfer function can only be partly un-done with de-convolution; conditions are critical.