|A Portuguese/English team has took it upon themselves to collect a bunch of Perkin mauve relics from several museums dated between 1856 and 1906, to put them through a series of chemical tests (DOI) with some surprising results. Several team members had in 2007 already identified a couple of new components in the Mauve mix (DOI) but now it turns out the dye consists of at least 13 derivatives of the same 7-amino-5-phenyl-3-(phenylamino)phenazin-5-ium core only differing with respect to methyl substitution pattern. |
The new study also reveals two different production processes. In original samples (dated 1856 and onwards) the phenazinium cation is accompanied by a sulfate anion. This salt is amorphous and poorly water-soluble. In 1862 Perkin replaced sulfate by an acetate ion making the dye more soluble and to improve crystallinity he increased the amount of O-toluidine in the formulation.
interestingly a sample cherished by the Science Museum (Link) as the original stuff turned out to be post 1862 material. A Mauveine specimen also in possession by the science museum and now declared genuine was donated by Perkin's daughter (or granddaughter, the article is fuzzy at this point) in 1947.
Update: in another case of what we can call chemical archeology, samples from the famous 1953 Miller-Urey experiment have been re-analysed by Johnson et al. via HPLC / Time-of-flight mass spectroscopy at the sub-picomolar (<10-12 M) level revealing many more amino acids than Miller (obviously using less sophisticated equipment) himself had reported (DOI). This new finding however does not change the significance of the Miller experiments.