PARAFAC2 - Part II. Modeling chromatographic data with retention time shifts

This paper offers an approach for handling retention time shifts in resolvi ng chromatographic data using the PARAFAC2 model. In Part I of this series an algorithm for PARAFAC2 was developed and extended to N-way arrays. It wa s discussed that the PARAFAC2 model has a number of attractive features. It is unique under mild conditions though it puts fewer restrictions on the d ata than the well-known PARAFAC1 model. This has important implications for the modeling of chromatographic data in which retention time shifts can be regarded as a violation of the assumption of parallel proportional profile s underlying the PARAFAC1 model. The PARAFAC2 model does not assume paralle l proportional elution profiles, but only that the matrix of elution profil es preserve its 'inner-product structure' from sample to sample. This means that the cross-products of the matrix holding the elution profiles in its columns remain constant. Here an application using chromatographic separati on based on the molecular size of thick juice samples from the beet sugar i ndustry illustrates the benefit of using the PARAFAC2 model. Copyright (C) 1999 John Wiley & Sons, Ltd.