1. Why we check for impurities
Aniline and N-methylaniline are starting materials or intermediates for chemically synthesized indigo, and they can remain as unreacted residues in the final powder. Because of their toxicity and possible carcinogenicity, certification standards including ZDHC, OEKO-TEX and GOTS limit the permitted concentration of these substances in textile dyes and in finished products. That is why we analyze both substances for each product and publish the results together with the detection limit.
Chemical structures of aniline and N-methylaniline
Aniline
C₆H₅NH₂ · CAS 62-53-3
N-methylaniline
C₆H₅NHCH₃ · CAS 100-61-8
This description does not exceed the scope stated on p.4 of the catalog (starting materials, intermediates, toxicity, carcinogenic potential).
Skeletal formulae drawn directly in code (SVG) from verified chemical structures. They were not produced with an image generation tool.
2. Indigo made by microbial fermentation
CutisBio uses a fermentation process that draws on the biosynthetic pathways of microorganisms to convert tryptophan obtained from biomass into indigo. Of the four indigo synthesis routes presented in the catalogue, this is the microbial route.
3. What the tests confirmed
In KATRI's ASTM D6866-24a Method B test, biobased carbon content was measured at 98% (pMC 97.73), and in KOTERI's KS K 0734 2019 test aniline and N-methylaniline were not detected (method detection limit 5 mg/kg). According to the catalogue, colorfastness is at a level comparable to plant and chemical indigo, and the grade for each item can be seen exactly as recorded in the tables on the data page.
