IQUIR   05412
INSTITUTO DE QUIMICA ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Direct analysis of chlorophylls a and b in olive oils using ultra-fast high-performance liquid chromatography and four-way calibration
Autor/es:
V. LOZANO, G. ESCANDAR.; A. MUÑOZ DE LA PEÑA, I. DURÁN, A. ESPINOSA
Lugar:
Úbeda
Reunión:
Congreso; VI Reunión de la Sociedad Española de Química Analítica; 2013
Resumen:
Determination of chlorophylls and pheophytins in olive oils usually involves HPLC methods with UV detection and, in general, the analysis time is long and the use of an ion-pair reagent in the mobile phase is needed. In all proposed methods, it is necessary to isolate the pigment fraction of olive oils by liquid-liquid extraction or by solid-phase extraction. The analysis of the pigment fraction has been usually performed by reversed-phase ion-pair chromatography with UV-Vis detection or in series with a fluorescence detector.In this report we describe, for the first time, a four-way multivariate calibration approach based on data obtained using UHPLC (ultra-fast HPLC) in combination with a fast-scanning spectrofluorimeter as detector. The data were obtained in a very short time operating in gradient mode . Emission-elution time three-way matrices (ETMs) have been easily measured for each experimental sample and the third data mode has been obtained by recording each ETM at different excitation wavelengths.For each sample, 61 emission spectra have been recorded between 620 and 680 nm, with data intervals of 1 nm, along the chromatographic run at intervals of 1.8 seconds. The excitation wavelengths were ranged between 350 and 490 nm in steps of 20 nm. The obtained four-way data were processed with severa! multi-way algorithms such as PARAFAC, U-PLS/RTL [1] and N-PLS/RTL [2] multivariate cal ibration algorithms. The figures of merit for the three procedures 11 w been calculated, and the best results were found when either U-PLS/RTL or N-PLS/RTL algorithms were used to perform the multivariate calibration.The methods were applied to the determination of chl a and b and phe a and b in olive oilsamples without previous treatments and without the isolation of the pigment fraction. A set of four monovarietal olive oil samples (cornicabra, picual, hojiblanca and manzanilla cacereña) where investigated with the aid of U-PLS and N-PLS, both combined with RTL, and a recovery study was carrying out so the samples were fortified with the tour pigments. In all cases, the statistical results were satisfactory, taking into account the complexity of th e olive oil samples anlyzed and the absence of pretreatment steps. The average recovery values found ranged from 85 to 106%.