LAUSR

Abstract K4[Fe(CN)6] and benzenedial isomers: catechol, resorcinol and hydroquinone, were studied by voltoabsortometry, absorption spectroscopy versus potential sweep, to generate second order data sets. Linear sweep voltammetry was used for K4[Fe(CN)6] and differential pulse voltammetry for benzenediol isomers. Quantitative models were constructed using the PARAFAC algorithm in samples of tap water with the addition of catechol, resorcinol and hydroquinone and RMSEP of 0.06, 0.07 and 0.03 mmolL−1 were obtained, respectively. For the U-PLS/RBL algorithm, the RMSEP were 0.05, 0.10 and 0.03 mmolL−1, respectively for catechol, resorcinol and hydroquinone. When the data set is derived with respect to the potential, PARAFAC recovers a derived kinetic profile that fits the voltammogram in the model system, K4[Fe(CN)6], but presents displacement in the benzenediol system and a break in the trilinearity of resorcinol. The RMSEP obtained for the derived data for PARAFAC were 0.06 and 0.05 mmolL−1 for catechol and hydroquinone, and 0.07, 0.04 and 0.07 mmolL−1 for U-PLS/BRL, for catechol, resorcinol and hydroquinone, respectively. Degenerate solutions were observed for PARAFAC models and confirmed by MCR-ALS with soft modeling closure constraint. It is observed that degenerate solutions should be expected in higher-order quantitative applications involving spectroelectrochemistry data. Although degenerate solutions are not a pure component solution, they do not affect quantitative models.