Dimethyl Yellow

CI 11020; 4-dimethylaminoazobenzene; C₁₄H₁₅N₃ = 225.3 (60-11-7)

Produces a red colour in moderately acidic alcoholic solutions and a yellow colour in weakly acidic and alkaline solutions (pH range, 2.8 to 4.6).

Complies with the following test.

Homogeneity Carry out the method for thin-layer chromatography, Appendix III A, using silica gel G as the coating substance and dichloromethane as the mobile phase. Apply to the plate 10 µL of a 0.01% w/v solution in dichloromethane. The chromatogram shows only one spot.