Abstract: The computation method and the differences between components are the dominated factors which affect the accuracy of an analytical determination with computation spectrophotometry.Computational-derivative spectrophotometry, based on taking advantage of the higher resolution of derivative spectrum, was proposed for the simultaneous determination of multicompo-nents. The additivity of derivative spectra and the selection of measuring points are important factors for this method. The measuring points were selected in different order derivative spectrum according to the condition number of the coefficient matrix. The concentrations of the components were calculated by solving a group of equations. The analytical applicationof the method to the W/Mo-SAF-CTMAB proves that the method is quite simple andaccurate.

Key words: derivative spectrophotometry, tungsten, molybdenum