Chemometric modeling of kinetic-fluorescent third-order data for thiamine determination in multivitamin complexes

•The thiochrome formation kinetic was followed by fluorescence matrices acquisition.•A 3rd order method for thiamine in multivitamins complexes was proposed using PARAFAC.•Standard addition was used with 3rd order kinetic-fluorescence dataset for first time.•Thiamine content was estimate in multivitamins complexes in the presence of interferences.

Thiamine (vitamin B1) was converted into a fluorescent thiochrome by oxidation catalyzed by Hg2 + in alkaline medium. The kinetic evolution for this conversion was followed by emission-excitation spectroscopy generating a third-order dataset for each sample, and a four-way data array for a group of samples. The data were analyzed by parallel factor analysis (PARAFAC), which presents the second-order advantage, allowing to estimate the analyte concentrations even in the presence of unknown fluorescent interferences. On the other hand, the second-order advantage does not prevent matrix effects or interferences affecting the reaction mechanism or kinetic properties. For this reasons, standard addition is needed in order to develop a quantitative method for thiamine determination in multivitamin complexes acquired in the local market. The thiochrome emission, excitation and time profiles are correctly isolated in all samples, and the concentration of thiamine in the latter ones was estimated with a deviation lower than 10% of their nominal values.