Spectrophotometric determination of melamine in milk by rank annihilation factor analysis based on pH gradual change-UV spectral data

► We introduce a simple, sensitive, selective and low cost procedure for direct spectrophotometric determination of melamine in milk samples by applying RAFA to pH gradual change-UV spectral data (pH-spectra). ► We recorded the changing spectra and obtained the bilinear matrix of pH-spectra. Based on these data, the concentration of melamine in samples could be predicted by RAFA with satisfactory results. ► The complicated pre-separation operation is not needed. ► The approach is simple to producing second order data. ► The apparatus required in this method is easily obtainable.