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EC number: 445-790-1
CAS number: 404362-22-7
Although computer estimations indicated a potential overestimation of
the experimental partition coefficient for a number of components, QSAR
calculations have been used to estimate the organic carbon-water
partition coefficient. The experimental log Kow was >6.2 and this value
was usedin the calculation although computational estimations suggested
that the partition coefficient had been possibly overestimated due to
secondary interactions between the surface active test substance and the
analytical column. The high octanol-water partition coefficient was
chosen as a worst case option since at pH's found in the environment,
the amine groups present on the test material will be ionised. Typically
cationic species bind strongly to soil due to partitioning onto organic
matter and also ionic interactions with clay particles.
The organic carbon-water partition coefficient (Koc) of the substance
MXDA/SM ADDUCT was determined in accordance with EU Method C.19 under
GLP. In a preliminary test performed at pH 3 and pH 7, the suitability
of a cyano column for the HPLC test was studied. It was demonstrated
that the test material was present in an ionised form over the range of
tested pH values. The surface chemistry of the stationary phased of the
HPLC column altered significantly depending on the pH value, with
residual free silanol groups being deactivated under acidic conditions.
As the test material was retained at pH 7 but eluted at pH 3, it was
evident that retention of the substance was not only due to partitioning
but was also due to secondary ionic interactions with free silanols. The
main determination of the Koc thus could not be completed at pH 3 as
this exceeded the valid environmental range of the method. Since the
HPLC method was not valid due to the ionic interactions with the
stationary phase, an estimation of the Koc was performed by QSAR
calculations using the KOCWIN computational tool (version 2.0, Syracuse
Research Corporation). The Koc in the relevant equation for
non-hydrophobic substances was based on the Log Kow of the substances by
using the following equation: log Koc = (0.52 x log Kow_experimental) +
1.02. Considering the experimental value for the log Kow of >6.2, the
value for the organic carbon-water partitioning coefficient was
calculated as log Koc >4.24. Although computational estimations may
potentially overestimate the Koc, this calculated value was considered
as a reasonable worst case estimation given that the substance may occur
in an ionised form under environmental pH conditions. This is because
the amine groups present on the test substance will be ionised at pH
values found in the environment and the cationic species tend to bind
strongly to soil due to partitioning onto organic matter or interactions
with clay minerals. In conclusion, it can be expected that the substance
MXDA/SM ADDUCT has the potential to adsorb to soil and sediment
particles under environmental conditions.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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