Violet dyes of the 1860s: Hofmann, Britannia, violet de Paris, Wanklyn's, and Crystal violet (1883)

Two 19th-century historical violet dyes from the Historische Farbstoffsammlung, Technical University of Dresden, have been analysed by liquid chromatography-mass spectrometry (LC-MS). The data are presented as charts with retention time and two scales: electron spray mass spectrometry counts (m/z) and milli-absorption units (UV). These dyes are complex mixtures as anticipated from the synthetic methods involving partial alkylation of rosaniline or synthesis using mixtures of N-methylaniline and N,N-dimethylaniline. The charts typically show chromophores separated by CH2 units which have separated well. Hofmann's violet is presumably made by Hofmann's method of synthesis, but the analyses do not verify with certainty who the inventors are because of the complexity of the dye mixtures.