DIGITAL SIGNAL PROCESSING TECHNIQUES APPLIED TO CHROMATOGRAPHY

Abstract

The field of analytical chemistry has always taken advantage of advances from other fields. The application of digital signal processing techniques to chromatographic systems has been shown to enhance the chemical information concerning the solute-adsorbent interaction. Applying the techniques of Fourier transforms, spectrum analysis, correlation, and convolution has expanded the scope of multiple injection type experiments. A review of these signal processing techniques relevant to analytical chemistry is given. The effects of restricting the concentration range a solute undergoes was the impetus for a new type of multiple injection experiment, known as frequency modulated (FM) correlation chromatography. By limiting the deviation in concentration to a small portion of the isotherm, gaussian shaped peaks can be obtained even when working in a nonlinear portion of the isotherm. The characterization of the experimental parameters in FM experiments (i.e. carrier frequency and modulation bandwidth) and the effects on peak shape, retention time, and signal-to-noise ratios was evaluated. The FM multiple injection technique was then applied to the study of linear and nonlinear behavior on a homogenous (i.e. Porapak) and heterogeneous (i.e. Durapak) chromatographic support. Specific types and strengths of solute-adsorbent interacts are proposed. The implications of multiplex and modulated techniques to linear system chromatography and the isolation of extra-column band-broadening effect (via a Fourier deconvolution approach) in modern open tubular GC and HPLC conclude this work.