Factorial design for optimising chromium determination in tanning wastewater

A totally automatized procedure for determining chromium by sequential injection analysis (SIA) linked to multivariate curve resolution with alternating least squares (MCR-ALS) is proposed. With this system Cr(III) is oxidised to chromate (Cr(VI)) and this form is then converted to dichromate in order to obtain second order data. The experimental design method was used to establish the best conditions. The identification of the most influential factors was validated using ANOVA tests. We used this method to successfully analyse total chromium in several aqueous tannery samples from various steps of a tanning process. The results from this method and those from the atomic absorbance spectroscopy (AAS) method are comparable. Sample frequency was 30 samples h− 1.