Photoinduced fluorimetric determination of folic acid and 5-methyltetrahydrofolic acid in serum using the kinetic evolution of the emission spectra accomplished with multivariate second-order calibration methods

JIMENEZ GIRON, A.; DURAN MERAS, I.; MUNOZ DE LA PENA, A.; ESPINOSA MANSILLA, A.; CAÑADA CAÑADA, F.; OLIVIERI, A. C.

ANALYTICAL AND BIOANALYTICAL CHEMISTRY

Springer

Lugar: Berlin; Año: 2008 vol. 391 p. 827 - 835

1618-2642

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:none; mso-layout-grid-align:none; text-autospace:none; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:ES-TRAD;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:none; mso-layout-grid-align:none; text-autospace:none; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:ES-TRAD;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Second-order multivariate calibration methods in combination with a continuous flow system, which allows for the continuous on-line irradiation of the analytes, have been employed for the determination of folic acid and its main metabolite 5-methyltetrahydrofolic acid in serum samples. An experimental central composite design, together with the response surface methodology, has been used to find the optimum instrumental variables to perform the photochemical reaction. The time evolution of the emission spectra of the generated photoproducts, in the range 330-540 nm, after irradiation at 275 nm during 20 minutes, provided the three-way data set employed. On the basis of the differences on the kinetic rates of the photoreaction of both analytes, direct determination of them in human plasma has been accomplished. The second-order methods assayed were parallel factor analysis (PARAFAC), self-weighted alternating trilinear decomposition (SWATLD) and unfolded partial least-squares (U-PLS), multidimensional partial least-squars (N-PLS) and bilinear least-squares (BLLS), all three in combination with the residual bilinearization procedure (RBL).