Stains, Dyes, Inks and Indicators.


[Work done in the Department (1950's) on logwood dyes, to go here.]
Structures of hematein and hematoxylin. A brief history of their use is given in Woods and Ellis, Laboratory Histopathology: A Complete Reference, 1994 Churchill Livingstone.
These dyes are extracted from haematoxylon campechianum and are chemically very similar to the dyes brazilein and brazilin from the caesalpinia redwoods such as caesalpinia brasiliensis (which is where the name for the country Brazil is derived). Another important species is pernambuco or fernambuco wood (caesalpinia crista) which is the timber predominantly used for the manufacture of bows for violins, cellos etc.



Whilst the use of the dyestuffs from Bixa orellana has been known for many years, it was only introduced into Europe in the 16th Century. The crude extract, called annatto, gives rise to a red, light red or yellow dye and the first isolation of the principal agents was by Boussingault around 1825.
("Sur les proprietes chimiques du rocou", Ann. Chem., 1825, 28, 440-444.)
It is used extensively in the food industry for dyeing dairy products (E160b). These dyestuffs are carotenoids and recently a biosynthetic pathway from lycopene to bixin was identified by introducing genes into bacteria preengineered to produce lycopene. It was suggested that bixin-producing tomatoes would even be feasible in a few years!


These are the water soluble compounds responsible for the red to blue colours in fruits and vegetables such as grapes, strawberries, apples, red cabbage, etc.

In general they are glycosides of anthocyanidins, where the sugars are usually glucose, galactose, rhamnose or arabinose. A Table showing the structures of 18 anthocyanidins is available.

The extinction coefficient for the anthocyanine dye E163 is reported for a 1% solution in 1 cm cell to be 1120 at 537 nm. A dilute solution gives the following spectrum, E163.

Beetroot red, betanin

As much as 200 mg of betanin is found in beetroot.


For some background information on the cochineal insect see the reports at and U. of Minnesota.
The structure of carminic acid is available. Note that both haematein and cochineal were mentioned by Robert Hooke in 1650 although they both must have been known to the indigenous people of the Caribbean and Mexico for much longer.

Cochineal and carmine are discussed on the colormaker site.


Curcumin from turmeric is a yellow dye


that is extremely heat stable but light sensitive. Best to keep your curry powders in the dark therefore.

For a range of other spectral files, see the site at Lappeenranta University of Technology.

The RAMAN spectra of a number of prehistoric dyes and natural pigments have been recorded and are available as GRAMS .spc files for download from University College, London. Permission has been obtained to convert two of these to JCAMP-DX format, and they are available below, namely:
saffron and Prussian Blue.


A starting point is "well known litmus", except that the structure is still not well established since the solution used in laboratories is a mixture of perhaps more than 6 species.

visible spectrum of litmus

The visible spectra in acid or base have been recorded and saved in JCAMP-DX block format.

The structures of some common acid base indicators along with the theory behind their use is presented at Imperial College.

The structure and spectra (in Galactic SPC format) of a range of dyes is available at The University of Southern Carolina-Aiken

The history of dyes from 2600 BC was presented at a gathering of weavers and spinners in Washington in 1982.

Colouring matter as food additives
Dr Bird logoReturn to Chemistry, UWI-Mona, Home Page

Copyright © 1997-2014 by Robert John Lancashire, all rights reserved.

Created and maintained by Prof. Robert J. Lancashire,
The Department of Chemistry, University of the West Indies,
Mona Campus, Kingston 7, Jamaica.
Created April 1997. Links checked and/or last modified 8th November 2014.