title: Second order advantage in the determination of amaranth, sunset yellow FCF and tartrazine by UV-vis and multivariate curve resolution-alternating least squares.
abstract: A direct spectrophotometric method for the determination of three artificial colors--amaranth, sunset yellow FCF and tartrazine--in beverages samples is proposed. The spectra were recorded between 359 and 600 nm. The spectra of the samples (just filtrated), pure dyes (concentrations ranged between 0.01 and 1.8 mg L(-1) for amaranth, 0.08 and 4.4 mg L(-1) for sunset yellow and 0.04 and 1.8 mg L(-1) for tartrazine) and synthetic mixtures were disposed in a column-wise augmented data matrix. This kind of data structure, analyzed by multivariate curve resolution-alternating least squares (MCR-ALS) makes it possible to exploit the so called 'second order advantage'. MCR-ALS algorithm was applied to the experimental data under the non-negativity and equality constraints. As a result, the concentration of each dye in the samples and their corresponding pure spectra were obtained. The results were validated using internal reference materials and no significant differences were found (alpha=5%) between the reference values and the ones obtained with the proposed method. The second order advantage made it possible to obtain unbiased results even in the presence of interferences.
authors.affiliation: FIA Laboratory, Department of Chemistry, Universidad Nacional del Sur, INQUISUR (UNS-CONICET), Av. Alem 1253, (B8000CPB), Bahía Blanca, Buenos Aires, Argentina.
authors.forename: Natalia Elizabeth
authors.initials: NE
authors.lastname: Llamas
authors.forename: Mariano
authors.initials: M
authors.lastname: Garrido
authors.forename: María Susana
authors.initials: MS
authors.lastname: Di Nezio
authors.forename: Beatriz Susana
authors.initials: BS
authors.lastname: Fernández Band