Characteristics and application of an electrochemical concentration modulator in correlation chromatography: Part 2. Computational aspects, modelling and application

Abstract

An electrochemical cell was used as an injection device in correlation chromatography. The use of a conventional injection control signal combined with a conventional deconvolution method leads to the appearance of ghost peaks in the correlogram. Several methods to suppress or correct for the presence of ghost peaks in the correlogram were studied, taking into account the electrochemical cell characteristics determined in the first part of this paper. An overview is given of existing time-domain deconvolution methods with emphasis on the shape of the virtual injection. Fourier-domain deconvolution methods are discussed and compared with time-domain methods. An improved model for the modulation process taking place in the electrochemical cell is used to calculate the real injection pattern. Three alternative methods to diminish the ghost peak phenomenon have been compared. First, deconvolution of the detector signal with a calculated or experimentally determined input pattern was examined. Secondly, intrinsic correction properties of correlation chromatography were used to remove the ghost peaks. Finally, the effect of adjusting the signal used to control the potentiostat was tested. The latter method proved to be the best solution. Calibration curves were measured to test the linearity of the method.