# How can I separate benzidine from a food colouring (FD&C red 40)?

I'm doing a research paper on the food colouring red $40$ (also known as Allura red) and the fact that it contains a carcinogen: benzidine.

I am having trouble finding a way to separate the benzidine $(\mathrm{C}_{12}\mathrm{H}_{12}\mathrm{N}_2)$ from red $40$ $(\mathrm{C}_{18}\mathrm{H}_{14}\mathrm{N}_2\mathrm{Na}_{2}\mathrm{O}_{8}\mathrm{S}_2)$ to determine the concentration of benzidine in the colour since they are both organic.

Paper chromotopgraphy wouldn't work because I need to quantify the amount of benzidine as well, which is the aim of my project.

I am a highschool student and I have very limited resources available to me and therefore the method of separation shouldn't be very complicated but instead, rather basic. Does anyone have any suggestions.

• You could possibly try paper chromatography. – NotEvans. Sep 2 '16 at 17:59
• Paper chromatography would help me to separate the two, however I wouldn't be able to quantify the amount of benzidine, which is really what my research paper is all about. – Ruhee Dawood Sep 2 '16 at 18:27