Reaction product of 9-[2-(ethoxycarbonyl)phenyl]-3,6-bis(ethylamino)-2,7-dimethylxanthylium chloride and Naphthalenesulfonic acids, reaction products with formaldehyde, ammonium salts

Partition coefficient

Description of key information

The log Pow of the test item was determined to be in range from log Pow 0.3 to 2.946 at 25 °C and pH=7.

Key value for chemical safety assessment

Log Kow (Log Pow):

2.946

at the temperature of:

25 °C

Additional information

The key value for CSA is the experimentally determined worst case value.

A study was conducted in accordance with OECD TG 117 and Regulation (EC) No 440/2008 method A.8 to determine the partition coefficient of the test item. 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 % buffer (v/v). The resulting solution of 1 g/L, pH 7 was directly measured via HPLC-UV at 25 ± 1 °C. A pre-test was conducted to determine the retention time of the test item, 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 0.9593. 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.Six peaks were obtained in the chromatogramm of the test substance. Three peaks showed a relative area < 5% in were therefore considered as minor peaks and were not taken into account in the determination of log Pow of the test item. Two peaks lay outside the dead time of the method. Thus, the log Pow was not calculable and was stated as log Pow <0.3. The log Pow of the main peak was determined to be 2.945 at 25 °C and pH=7. No observations were made which might cause doubts concerning the validity of the study outcome. Thus, the log Pow for the test item was determined to be in range from 0.3 to 2.945 at 25 °C and pH=7.