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EC number: 447-920-2
CAS number: 897393-42-9
A QSAR for nonhydrophobics was used for log Koc estimation based on the
log Kow. The model was first reported by Sabljic and Güsten (1995) and
mentioned in the TGD (2003). Validity of model:
1. Defined endpoint: adsorption/desorption (log Koc).
2. Unambiguous algorithm: linear regression QSAR; log Koc = 0.52 x log
Kow + 1.02.
3. Applicability domain: all chemicals not classified as hydrophobics,
with a log Kow below 8.0 (and above -2.0).
4. Statistical characteristics: n = 390; R2 = 0.63; SE = 0.56.
5. Mechanistic interpretation: related to the partitioning of the
substance from water into the organism's lipid phase.
Adequacy of prediction:
The substance falls within the applicability domain described above and
therefore the predicted value can be considered reliable. However, next
to a standard error of 0.56, it is mentioned that for aliphatic amines
the model generally underestimates the log Koc by 1 -2 log units.
Therefore, as long as no testing data or more accurate QSAR predictions
are available, the estimate should be used with caution.
The estimated partition coefficients (log10 Pow) and resultant
calculated adsorption coefficients (log10 Koc) of the test item
component 1: log10 Pow = -0.35 and log10 Koc = 0.84 (before correction)
component 2: log10 Pow = 0.28 and log10 Koc = 1.17 (before correction)
As the adsorption coefficient of alkyl amines maybe systematically
underestimated by the method by 1 or 2 log units, the maximum possible
correction factor was applied to the results to represent a worst case
scenario. This resulted in estimated values of log10 Koc = 2.8 and 3.2
for components 1 and 2, respectively.
Based on the results of a batch equilibrium experiment in which the
adsorption of the substance to three different soils with varying
properties was investigated, a key Koc value of 49.7 (geometric mean of
three Koc values) was selected as key value for the CSA. This
corresponds to a log Koc value of 1.7. Because pH was not monitored in
the aqueous solution, the pH dependency of adsorption of this ionisable
substance could not be evaluated. Therefore the study was scored as
Based on a calculation of the pKa's and the results of the
determination of the log Kow, it is clear that the test substance is
ionized for at least 10% in the range pH 5.5 -7.5. Therefore both the
ionized and the unionized form should be tested in appropriate buffer
solutions. Since the highest pKa was calculated to be 9.9, the test
substance must be tested both at a pH of > 10.9 (neutral form) and at a
pH < 8.9 (ionized form). Due to the limited pH range of the cyanopropyl
column required for the OECD 121 method, testing at pH > 10.9 is
impossible. Testing at pH < 8.9 is in principle possible, but due to the
very unfavorable interaction of the protonated form of the test
substance with residual silanol groups of the stationary phase, test
substance peak shape and retention time reproducibility will be
extremely poor. Therefore, it is not possible to determine the partition
constant according to the OECD 121 method (HPLC method).
Alternatively, a batch equilibrium test was performed
(Environmental Testing Laboratory, 2012) according to a guideline
similar to OECD guideline 106. In this study, the adsorption of the
substance was studied in three different Chinese soils with variable
properties (pH, organic carbon, CEC, % clay). The log Koc values
obtained in these soils range from 1.52 to 1.79. Although for this
substance it would have been interesting to investigate pH dependency of
adsorption, no information on this is obtained since pH was not
monitored in the aqueous phase. Therefore, this study was scored as
As supporting information, several QSAR estimates can be used. The
QSAR for nonhydrophobics reported by Sabljic and Güsten (1995) and
reported in the TGD (2003) of the European Commission yields a log Koc
of 2.06 (using a linear regression equation based on the log Kow). This
value may be underestimated since the model may underestimate the log
Koc of aliphatic amines by 1-2 log units. Therefore, the value should be
used with caution. NOTOX Project 375637 presents another QSAR prediction
(also based on log Kow), in which the final values were (worst case)
corrected for the possible underestimation for aliphatic amines. The
resulting values were log Koc = 2.8 and 3.2 for two components,
respectively. Here too, these values should be used with caution.
Therefore, both QSAR estimates represent supporting information.
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