Window target-testing factor analysis: theory and application to the chromatographic analysis of complex mixtures with multiwavelength fluorescence detection

Window target-testing factor analysis (WTTFA) is a new data analysis method that can help confirm the presence or absence of an analyte in a severely overlapped chromatogram. It is intended to be used in chromatographic applications with multichannel detection and is based on principal component analysis. The algorithm attempts to determine if the response profile of a target analyte lies within the response subspace of a time window containing unresolved chromatographic peaks. Because the window moves sequentially through the chromatogram, WTTFA allows a relative assessment of match quality. To test the new method, a procedure for simulating complex chromatograms has been developed. The simulated data allow the limitations of WTTFA to be tested under different conditions of chromatographic complexity, spectral overlap, measurement noise, window size and other factors. As a practical demonstration of its utility, the method is applied to the chromatographic analysis of polycyclic aromatic compounds in a complex petroleum distillate using multiwavelength fluorescence detection. WTTFA indicates the presence of l-methylpyrene in an unresolved cluster of peaks. This is confirmed through a combination of mass spectrometry, heart-cut chromatography and self-modeling curve resolution. (C) 1999 Elsevier Science B.V. All rights reserved.