IQUIR   05412
INSTITUTO DE QUIMICA ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
On line photochemically induced excitation-emission-kinetic four-way data. Analytical application for the determination of folic acid and its two main metabolites in serum by N-PLS/Residual Trilinearization (RTL) calibration
Autor/es:
ALEJANDRO CESAR OLIVIERI; MUÑOZ DE LA PEÑA, ARSENIO; JIMENEZ GIRON, ANA; DURAN MERAS, ISABEL; ESPINOSA MANSILLA, ANUNCIACIÓN
Lugar:
Montepellier
Reunión:
Congreso; 11 Conferencia Internacional de Quimiometria en Quimica Analitica; 2008
Resumen:
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Folate derivatives act as
co-enzymes in several enzymatic reactions giving rise to methyl and formyl
transfer in the biosynthesis of amino and nucleic acids. Folate deficiency may
be linked to several pathological alterations such as pregnancy complications,
neural tube defects and other numerous well established pathologies [1, 2].
Folic acid (FA) is administered to counteract the toxic effects of antitumoral
drugs such as methotrexate [3]. Tetrahydrofolic (THF) and
5-methyl-tetrahydrofolic acid (5MTHF) are the most important FA metabolites
involved in several biochemical routes in the human organism.
FA is a photosensitive
compound and is degraded to various products in aqueous solution by ultraviolet
and visible light and also by direct sun light. It has been demonstrated that
the excited heterocyclic moiety is involved in the photochemical reaction [4].
Although the conventional way to generate fluorescent pteridin rings from
tetrahydro- and dihydrofolates employed chemical oxidation [5, 6], the
photoirradiation may be a more simple and efficient mode to develop a
differential analytical methodology, by using chemometric tools in conjunction
with kinetic spectral information. The variation of the luminescent properties
of a folate derivative, monitored as its excitation-emission (EEM) fluorescent
matrix during the photoirradiation process (a third-order signal), may produce
a selective information for both substituted and non substituted folate.
Third-order data for several
samples can be arranged into four-way arrays, which have been recently proposed
for the resolution of mixtures of components in complex samples. They provide
the opportunity of introducing an additional dimension to second-order data (which
form three-way data sets), allowing for a theoretical increase in the
predictive ability of the models. They also exploit, in some cases, the second-order
advantage.
As a precedent on the use of
photochemically-induced four-way data arrays, Kim et al [7] described the analysis of photocatalytically enhanced
fluorescence EEMs with parallel factor analysis (PARAFAC). The time-dependent photocatalytic
degradation of polycyclic aromatic hydrocarbons (benzo[a]anthracene,
benzo[k]fluoranthene and dibenzo[a,h]anthracene) has been employed to create an
additional analytical dimension. It was demonstrated that the subsequent
four-dimensional degradation-EEM data arrays had greater selectivity for each
PAH than the three-dimension EEM data alone.
Two recent reviews on multiway
calibration [8,9] described modern advances and applications in this field, with
emphasis on analytical work. Usually, the time evolution of the analytical
signal (i.e., EEMs) is introduced to obtain the third dimension.
A new algorithm, multi-dimensional
partial least-squares (N-PLS) coupled to residual trilinearization (RTL), was
recently proposed by our group, and applied to the determination of procaine
and its metabolite, p-aminobenzoic
acid, in equine serum, by analysing four-way data based on recording the kinetic
evolution of fluorescence excitation-emission matrices [10].
In the present work, the
simultaneous determination of folic acid and its two main metabolites is
proposed and applied to serum samples. The analytical performances of several multi-dimensional
algorithms were compared and the best results were found with the N-PLS/RTL
combination.