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REACH

Substance Identification

C. How to report substance identification in IUCLID

What is the substance type of an inorganic substance with variable stoichiometry and how should this variability be reported in the IUCLID dossier?

The substance is in principle identified as an inorganic UVCB due to the variability of the molecular formula.

In this case please select “inorganic” as origin under the Type of substance heading of IUCLID section 1.1.

The variability in the stoichiometry should be reported under the molecular formula field (e.g. MxGyO2, x=a-b, y=c-d).

In case only one constituent block is reported in section 1.2 of the IUCLID dossier, a justification for reporting a single constituent in the composition of a UVCB substance (expected to have a variable complex composition) should be provided in the “justification for deviations” field.

One example of a valid justification would be:
“The substance is a UVCB due to variations at the elemental level and these variations cannot therefore be represented by reporting different constituents but only in the form of a variable molecular formula.”