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Physical & Chemical properties

Partition coefficient

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partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012-01-17 to 2012-02-07
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to guideline
EU Method A.8 (Partition Coefficient)
GLP compliance:
yes (incl. QA statement)
Type of method:
flask method
Partition coefficient type:
Analytical method:
other: UV-spectrophotometric analysis
Key result
log Pow
Partition coefficient:
25 °C
6.35 - 6.93

In the preliminary estimation, the partition coefficient of NMMO was estimated from the aqueous and octanol solubility as -0.97 log units. As a result, the shake-flask method was selected for the analysis.

Analytical determinations

The following individual results were obtained:

1:1 ratio, duplicate logPow values: -1.20 / -1.20, pH 6.9

1:2 ratio, duplicate log Pow values: -1.14 / -1.14, pH 6.4

2:1 ratio, duplicate log Pow values: -1.25 / -1.25, pH 6.4

The partition coefficient determined from all the ratios applied were found to be within the acceptable limit of ± 0.3 log units with a mean log P of -1.20 at pH of approx 6.6.

The octanol/water partition coefficient (log Pow) of NMMO was determined as -1.20 at pH 6.6 and 25°C.
Executive summary:

The partition coefficient of the test item was determined according to EU Method A.8. by applying the shake-flask method. The octanol/water partition coefficient (log Pow) of NMMO was determined as -1.20 at pH 6.6 and 25°C.

Description of key information

The log Pow of NMMO was determined in a GLP study according to EC Test Method A.8, flask shaking method, to be –1.20 at 25 °C (Younis, 2012).

Key value for chemical safety assessment

Log Kow (Log Pow):
at the temperature of:
25 °C

Additional information

Although the study was performed without pH adjustment, the pKa of the substance (5.14) suggests that the pH of the experimental study (approx 6.6) is high enough for having predominantly the uncharged molecule in the test solutions.