Fractional factorial design and simplex algorithm for optimizing sequential injection analysis (SIA) and second order calibration

In this study, we report a method for finding an analytical sequence that allows to simultaneously determine two analytes with very similar physical and chemical characteristics, such as amoxicillin and clavulanic acid, using sequential injection analysis (SIA) with a diode-array spectrophotometric detector and multivariate curve resolution with alternating least squares (MCR-ALS).This method comprises two stages. In the first stage, a fractional factorial design (26–2) is carried out in order to address the responses, reduce later experimentation and study how the factors, though confounded, interact with each other. In the second stage, optimization is carried out using the simplex algorithm.This method has advantages over response surface modelling, for example, when the number of significant factors is high. If simplex is begun in a suitable zone, the number of experiments may be considerably reduced.