dos Reis M. M., Biloti D. N., Pessine F. B. T., Ferreira M. M. C., “Human dental calculi analysis using total luminescence”. Porsgrunn, Norway, 15-19/08/1999: 6th Scandinavian Symposium on Chemometrics (SSC6), Program & Abstracts, 89 (1999). Poster P29.
Human dental calculi analysis using total luminiscence
M. M. dos Reis, D. N. Biloti, F. B. T. Pessine and
M. M. C. Ferreira
Department of Physical Chemistry, Institute of Chemistry,
State University of Campinas -
UNICAMP, 13081-970, Campinas, SP, Brazil, e-mail:
marcia@iqm.unicamp.br
Keywords: Porphyrins, excitation-emission spectroscopy, chemometrics, GRAM.
Human dental calculi possess porphyrins at low concentration
[1], which can be detected by
luminiscence spectroscopy.
In this work, the porphyrin emission spectra were monitored
in a range of excitation
wavelengths, producing a two-dimensional array of data
for each sample, where each row is
an emission spectrum and each column an excitation scan.
Three human dental calculi samples were dissolved in hydrochloric
acid 1:1 (v/v). Visible
luminiscence spectra were obtained on an SLM-AMINCO Spectrofluorimeter
(SPF-500C),
with a Xe lamp (250 W) as excitation source.
The Generalized Rank Annihilation Method (GRAM) [2] was
applied to the data for bilinear
curve resolution. An algebraic pretreatment and a similarity
transformation were used to
search for the best vectors to represent the resolved
spectra in the bilinear space. As
pretreatment Gaussian splines were used to represent
the spectra in the same basis set and
eliminate the experimental noise. To resolve the spectra,
GRAM was applied taking the rank
of the matrices largen than the expected value. The resulting
spectral profiles were obtained
using GRAM under some physically meaningful constraints
(spectra being non-negative and
with the peak maximum separation larger than the instrument
resolution) and the
concentration ratio matrix taken as diagonal.
The final result shows four porphyrinic profiles, which
were identified considering the Soret
band region and the resolved spectra for animal calculi
[1].
References
[1] Ferreira, M. M. C. et al.; Appl. Spectrosc.,
49,
1317 (1995).
[2] Sanchez, E. and Kowalski, B. R.; J. Chemometr.,
2,
265 (1988).
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