PARAFAC for spectral curve resolution: A case study using total luminescence in human dental tartar

Chromophore identification in biological samples often requires the physica l separation of the compounds, which can be difficult. Although there are s everal advantages to hyphenated spectroscopic techniques for identification of substances, complex mixtures of chromophores presenting overlapped spec tra cannot be identified directly through this method. This work presents a n application of chemometrics to compound identification in biological samp les by a spectroscopic hyphenated technique using a curve resolution method . The PARAllel FACtor analysis model (PARAFAC), which has no rotational ind eterminacy, was used for curve resolution of excitation-emission spectra of human dental tartars. PARAFAC was applied under constraints (i.e., unimoda lity and non-negativity) and evaluated with a validation procedure. The res olved profiles are porphyrinic-like spectra presenting excitation band maxi ma at 407, 416, and 431 nm in the Soret band region (390-440 nm) of these s ubstances.