Here's a link to the page:

Why does it say "dye content 80%"?

Shouldn't it be pure if it's a packaged powder?

Is it 20% other chemical compounds (e.g. stabilizers)?

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    – Jan
    Jun 26, 2016 at 21:22
  • 2
    $\begingroup$ tbh I'd just mail Sigma Aldrich to ask. $\endgroup$
    – Aesin
    Jun 26, 2016 at 22:00

1 Answer 1


Many dyes are sold as powders with 80-90 % purity. It is because some dyes are difficult to purify (e.g. they are difficult to crystallize). The remaining 10-20 % are impurities, such as isomers or closely chemically related side-products, but mostly they are "volatile impurities" (i.e. water). For most purposes these impurities do not interfere, so nobody bothers to remove them. Here is MSDS of Allura Red: http://www.vidhifoodcolour.com/uploads/gallery/14067976084allura_red.pdf


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