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  • Title: 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 U-PLS and N-PLS/residual trilinearization (RTL) calibration.
    Author: Jiménez Girón A, Durán-Merás I, Espinosa-Mansilla A, Muñoz de la Peña A, Cañada Cañada F, Olivieri AC.
    Journal: Anal Chim Acta; 2008 Aug 01; 622(1-2):94-103. PubMed ID: 18602539.
    Abstract:
    The determination of folic acid and its two main serum metabolites, 5-methyltetrahydrofolic acid and tetrahydrofolic acid, has been accomplished using four-way data modelled by the third-order multivariate calibration methods unfolded and N-dimensional partial least-squares (U-PLS and N-PLS), in combination with the separate procedure known as residual trilinearization (RTL). The four-way data were acquired by following the photochemical reaction of these compounds by on line irradiation with a UV lamp. The excitation-emission matrices (EEMs) were recorded as a function of the irradiation time, using a fast scanning spectrofluorimeter. The method achieves selectivity from the different rates at which the corresponding photoproducts of the folic acid derivatives are formed and degraded. Several N-dimensional chemometric algorithms were used and the method was applied to the determination of these compounds in serum samples. The best algorithms to perform the multivariate calibration were U-PLS and N-PLS in combination with the separate residual trilinearization procedure, achieving the second-order advantage. The approach allows minimizing or eliminating traditionally time-consuming sample pre-treatments and can facilitate quantifying an analyte in its native environment.
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