Determination of Sudan I in chilli powder from solvent components gradual change–visible spectra data using second order calibration algorithms

It was discovered that a second order spectra data matrix of Sudan I produced from the solvent components gradual change–visible absorption spectra can be expressed as the combination of two bilinear data matrices. Based on this discovery, a new method for the determination of Sudan I in gray systems using second order calibration algorithms has been developed. The second order calibration algorithms were based on the popular parallel factor analysis (PARAFAC) and rank annihilation factor analysis (RAFA), respectively. In the method described here, the components of the solvent were changed gradually by adding ethanol into cyclohexane, the absorption spectra of Sudan I and chilli samples in a series of cyclohexane–ethanol mixed solvents with various ethanol volume fractions were recorded, and then the second order data were obtained from the solvent components gradual change–visible absorption spectra. Thus, the concentration of Sudan I in a gray system could be determined from the spectra matrices using second order calibration algorithms. This method is simple, convenient and dependable. The method has been used to determine Sudan I in chilli powder with satisfactory results.