Detection of picramic acid and picramate in henné products by NMR spectroscopy

Painting and body art are increasing their utilisation as well as their cultural impact, since piercing and tattoos are expanding social phenomena, involving many young people. However, the utilised materials often enter the market with insufficient control and several cases of skin damages are reported. Safety of the utilised products must be ensured by adequate quality controls which must be easily made, rapid, low cost, clear and persuasive. The method here reported, regards the analysis on the possible presence of picramic acid in the ethyl acetate extracts of commercial henné powders by NMR Spectroscopy. In the proton spectrum, three sets of peaks could be detected, corresponding to the three classes of makers resonances: hennosides, typical markers of Lawsonia inermis, the henné plant; picramic acid or picramate; fatty acids. In particular, the set of signals corresponding to hennosides can be used as markers of the utilisation of the correct raw material of henné.