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Partition coefficient

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partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to guideline
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
according to guideline
EU Method A.8 (Partition Coefficient)
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC method
Partition coefficient type:
Analytical method:
high-performance liquid chromatography
Key result
log Pow
Partition coefficient:
< 0.3
25 °C
Details on results:
The retention time of the substance was lower than the retention time of the reference item with the lowest log Pow
The log Pow of the test item is stated as < 0.3
Executive summary:

The study was perfomed using a HPLC with a C18 column. Six reference items with different retention times were used to produce a calibration curve, since retention time on hydrophobic columns and Pow are correlated. The reference items were chosen on behalf of the pre-test.

First, a solution of the reference items was analysed with HPLC, then a solution of the test item; and finally again the solution with the reference items. Each analysis was performed three times, totalling to nine runs.

For each reference item, the capacity factor K was calculated from the retention time of thio urea and the retention time of the respective reference item. A calibration function (log K versus log Pow, linear fir) was determined using the literature values for Pow of the reference items and the retention times in the six determinations.

The chromatogram of the test item gave one large peak at 1.3 minutes. With the calibration function log K versus log Pow, the corresponding log Pow was determined with: < 0.3.

The peak lies within the deadtime of the method and not within the range of log Pows of the reference items. Therefore, the corresponding log Pows should be stated as < 0.3. It is thus concluded that the test item has a log Pow of < 0.3.

Description of key information

The partition coefficient of 2,2'-azobis[2-methylpropionamidine] dihydrochloride is stated as < 0.3. For the chemical safety assessment, a value of 0.3 was assumed.

Key value for chemical safety assessment

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

Additional information