Preparation and spectral compilation of FD&C Red No.40 intermediates and subsidiary dyes.

FD&C Red No. 40 may contain higher or lower sulfonated subsidiary dyes, depending on the purity of intermediates used. Samples of 10 possible subsidiaries were prepared and purified. They are to serve as analytical standards to aid in the identification of unknown compounds frequently appearing during the analysis of certification samples. Visible, ultra-violet, and infrared spectra as well as absorptivites and molar extinction coefficients are given for each dye.