SWFA is a technique using window information for the direct determination of the spectra of the eluting compounds without first calculating the concentration profiles. A further development is in a technique for iterative refinement of concentration profiles using so-called elementary matrix transformations starting from a set of spectra selected to be from as pure components as possible. This work is together with Bj rn-Vidar Grande. The advantages of this technique lie in its speed and ease of application. Two papers have been published.
More work is likely to come.
Missing data is a common situation in analytical chemistry. It might arise, e.g., because of instrumental failure or because the recorded signal is outside detection limits. Grung discusses the influence of missing data upon principal components analysis. It was found that current commercial programs did not always handle this problem correctly unless one restricts the calculation to only one principal component. The paper presents an iterative scheme which handles any number of principal components simultaneously.