Ferreira M. M. C., “The Trilinear Decomposition of Animal Dental Calculus Samples”. New Hampton, NH, The United Stated, 31/07-05/08/1994: Gordon Research Conference on Statistics in Chemistry and Chemical Engineering. Poster.

THE TRILINEAR DECOMPOSITION OF ANIMAL DENTAL CALCULUS SAMPLES
 

                        Márcia M. C. Ferreira
 

       Instituto de Química, Universidade Estadual de Campinas,
                    Campinas, S.P.  13081   Brazil
 

In the recent chemometrics literature, several papers have appeared
dealing with so-called second and third order data analysis methods.
Higher dimensional data are generated by hyphenated instruments that
have become commonplace in analytical laboratories.
Emission-excitation fluorescence, for example, is one of such hyphenated
techniques that generates two dimensional array.
However, while the theoretical research on such methods progresses nicely,
there have been very few applications.
Samples of the fluorescent dog and cat calculus studied as an indicator
of dental deposits provide an ideal application for the chemometric
analysis of fluorescent spectra of similar molecules. The Trilinear
Decomposition (TLD) method (1), has been applied to two dimensional
data arrays consisting of emission spectra (from 460 to 750 nm)
taken at excitation wavelengths in two nanometer increments from 390 to
450 nm from cats and dogs samples (each row is an emission spectrum and
each column is an excitation scan).
From the analysis of seven samples (four from cats and three from dogs),
it was possible to separate three different species with excitation
wavelengths (Soret spectral peaks) at approximately 408, 418 and 436 nm.
These components have porphyrinic character as indicated by their Soret
bands.
The analysis of the four cat samples showed the presence of the three
porphyrins. With a three factor model, two of the components could be
well deconvoluted (Soret bands at 408 and 418 nm). Although a reasonable
estimate for the third porphyrin (436 nm) was obtained, the emission
spectrum had a very small negative region and the excitation spectrum
was not unimodal as we would expect. This could the result of the
relatively small signal from this porphyrin when compared to the noise
and to the signals from the two other porphyrins.
For the three dog samples, the Trilinear Decomposition gave a good estimate
for the emission and excitation profiles of two porphyrins. They had
Soret bands at 410 and 436 nm. When the three factor model was used, the
estimated emission and excitation profiles of the third factor showed
significant negative region.

(1) Sanchez and Kowalski, J Chemom. 4, 29 (1990).

This project has been developed in collaboration with Prof. Martin
Gouterman's group.

PARTICIPATED IN THE PROJECT:
Márcia M. C. Ferreira (CPAC-UW                     Mary Lou Brandes UW
                on leave from UNICAMP-BRAZIL)      Ines M. C. Ferreira UW
Prof. Bruce Kowalski CPAC-UW                       Prof. Martin Gouterman UW