Spectrofluorimetric determination of chlorophylls and pheopigments using parallel factor analysis

In this study, parallel factor analysis (PARAFAC) was applied to fluorescen ce excitation emission matrices (EEM) of chlorophylls and pheopigments diss olved in acetone:water (9:1). The excitation wavelength range was from 350 to 500 nm and the emission was recorded from 600 to 730 nm. Nine standards, comprising mixtures of six analytes, were decomposed into a six-component PARAFAC model. Each component resembled the corresponding EEM of the pure a nalyte, demonstrating the uniqueness properties of PARAFAC. The score matri x obtained from the model was used for calibration and prediction of an ind ependent set of standards and for eleven samples collected in the Baltic pr oper. The results obtained by the proposed method were compared to classica l least squares (CLS) and to predictions by reference methods (HPLC and vis ible spectroscopy). For the independent set of standards the proposed metho d and CLS performed equal well in terms of predictive ability. But fur the samples the proposed method yielded results that were in good agreement to the reference methods, whereas CLS failed. Also the so-called "second-order advantage" was examined, showing that not all constituents must be include d in the calibration set. The concentration range was for chlorophyll a var ied between 10 and 75 mug l(-1) and similar for the other analytes. (C) 200 1 Elsevier Science B.V. All rights reserved.