BIVARIATE CALIBRATION AS AN ALTERNATIVE FOR ZERO-CROSSING TECHNIQUE IN THE RESOLUTION OF BINARY MIXTURES BY DERIVATIVE SPECTROPHOTOMETRY

In this work, the bivariate calibration algorithm is proposed as an alternative for the resolution of binary mixtures using derivative spectrophotometry. This algorithm involves the use of four calibration curves: two for each compound at two different wavelengths, selected by Kaiserʹs method. Four binary mixtures were studied (tartrazine-allura red; sunset yellow-erythrosine B; tartrazine-riboflavine and acetylsalycilic acid-caffeine) as representative examples where their resolution with the conventional zero-crossing technique is not suitable and, in each case, rather good analytical results were obtained using the bivariate method.