Joonsuk OH: I am not sure I understand your question! Here is an answer to
what I think you ask:
The natural red dyes as absorbed on the fibers are usually not pure
components. Madder (Colour Index Natural Red 8) is a mixture of hydroxy
anthraquinones. The pseudopurpurin (Colour Index 75420) is "probably
decarboxylated with [the] formation of purpurin (C.I. 75410) when the madder
root is dried." according Dr. Schweppe. There is also a difference between
the dyestuff (the plant material) and what is on the fiber. You need to
compare to a known dyeing of the natural dye--extracting the sample you know
to be dyed with madder and then extracting the unknown dyeing by the same
procedure; then doing a TLC to compare. If they match then you have
identified the unknown. Safflower on silk--it should be a pure
carthamin--but, in practice, it is very hard to remove all the yellow--so
that might be a mixture as well.
 
What system of preliminary separation are you using? HCl seems to give less
specific results (more general) than the 10% H2SO4.
 
With all best wishes, Mary Ballard
 
>>> *** <[log in to unmask]> 01/16/03 02:50AM >>>
I try to identify of ancient dyed textile by TLC(Thin Layer
Chromatography).
But pure componets of natural dye - eg munjistin etc.- as standards of
analysis was not found.
Who know extraction method of  munjistin, psudoprpurin and carthamin from
madder and  safflower for TLC analysis?
 
Joonsuk OH
 
National Folk Museum of Korea
Conservation Laboratory