Calculating total formaldehyde amount from dmdmH and formalin

this is the COA of DMDM hydantoin that says it has ~18% formaldehyde.

So will 0.2% of this preservative have the same amount of total formaldehyde as ~0.1% formalin which is 37% formaldehyde in water?


  • Bill_TogeBill_Toge Member, Professional Chemist
    it won't, because the amount of active preservative in the raw material is around 55% - the rest is water, so it would contain the equivalent amount as 0.055% formalin
    also, the amount of free formaldehyde is considerably less than than that (1% at most), as the rest of it is bound to the DMDM hydantoin molecule (the two -CH2OH groups attached to the nitrogens) and is only released when microbes attempt to ingest it
    so the actual amount of formaldehyde in solution is equivalent to 0.00055% formalin at most
    UK based formulation chemist. Strongest subjects: hair styling, hair bleaches, hair dyes (oxidative and non-oxidative) I know some stuff about: EU regulations, emulsions (O/W and W/O), toothpaste, mouthwash, shampoos, other toiletries
  • @Bill_Toge thanks for explanation.

    One more question.
    If in DMDM hydantoin 45% is wayer and ~18% is total formaldehyde, what is the rest of that? And does it function as a strong preservative as the rest of formaldehyde? 
  • This is the composition of DMDM hydantoin. That is why i said if 0.2% DMDM hydantoin is equivalent to ~0.1% formalin.
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