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Physical & Chemical properties

Partition coefficient

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Description of key information

The partition coefficient log Pow of the test substance was determined to be log Pow = 1.689 ± 0.003.

Key value for chemical safety assessment

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

Additional information

A study was conducted in accordance with OECD TG 111 and Regulation (EC) No 440/2008 method A.8 to determine the partition coefficient of the test substance. Using the HPLC method partition coefficient Pow was determined in three measurements. Therefore the test substance was dissolved in the mobile phase (65 % methanol and 35 % water (v/v). The resulting solution of 1 g/L pH 6-7 was directly measured via HPLC-UV at 25 ± 1 °C. A pre-test was conducted to determine the retention time of the substance, the dead time of the HPLC system and to choose the suitable reference items. In the main test the reference item mix were analysed in six independent measurements and the test substance in three measurements respectively. For each reference item, the capacity factor K was calculated from the retention time of thiourea and the retention time of the respective reference item. A calibration function (log K versus log Pow, linear fit) was determined using the literature values for Pow of the reference items and the retention times in the six determinations. The coefficient of determination r2 of the calibration function log K/Log Pow was calculated to be 0.9539. According to the guideline criteria this value was considered as sufficient to use the calibration function for the determination of the log Pow of the test item.

 Two peaks were obtained in the Chromatogramm of the test substance. Due to the water content of the mobile phase hydrolyses of the test substance could not be avoided. The peak of the hydrolysis product showed a relative area of < 5 %, and was considered as minor peak and was not taken into account in the determination of log Pow of the test item. No observations were made which might cause doubts concerning the validity of the study outcome. The log Pow of the test substance was determined to be 1.689 ± 0.00.3 at 25 °C.