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Physical & Chemical properties

Partition coefficient

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Description of key information

The log Kow of Cassiffix based on average weight of all peaks is 4.72 +/- 0.0112 (OECD TG 123).


The log Kow of Cassiffix's key constituents ranged from 4.71 to 5.1 after refinement (OECD TG 123).


The log Kow of the key degradation product of Cassiffix is 3, using HPLC (eq to OECD TG 117). The values actually ranged from 2.5 -3 because the exact time zero (dead time) could not be established and some alternatives were used, which gave slightly different values.

Key value for chemical safety assessment

Log Kow (Log Pow):
4.72
at the temperature of:
25 °C

Additional information

The log Kow of Cassiffix has been determined in several studies. The key study is done with the slow stirring method (OECD TG 123). From the water simulation study according to OECD TG 309 the log Kow values of the four main constituents were derived and considered to be supporting information. The log Kow of the key degradation product was also determined from this OECD TG 309 study and considered to be key information for the PBT assessment.


Log Kow of Cassiffix determined in the OECD TG 123 study


For Cassiffix, its constituents and impurities > 1%, the log Kow values were determined using OECD TG 123. The substance was solved in water saturated with octanol and stirred for 48h. Thereafter the solutions were rested to phase out and thereafter samples were taken from the water and octanol phase to measure the concentration in the samples. GC was then used to find the peaks of the constituents and impurities. The weighted average of all peaks were used to determine the log Kow for the substance as a whole. The octanol / water concentrations were then divided to find this weighted average, which was 4.72. To further present the log Kow values of the individual peaks further work was done and seven key peaks were used to find the log Kow range. These seven peaks could not be related to the chemical structures of the constituents and impurities because these chemical structures are too similar. These log Kow values ranged from 4.71 to 5.1. For Cassiffix as a substance the weighted average value log Kow of 4.72 will be used for the risk assessment.


Log Kow of the degradation product of Cassiffix and supporting information from the log Kow of the four constituents of Cassiffix


Introduction: The octanol/water partition coefficient (Kow) for degradation product of Cassiffix formed during the aerobic mineralisation in surface water study (OECD TG 309) was measured using HPLC.
Method: Concentrated water samples extracted with radiolabelled Cassiffix were extracted with dichloromethane and water residue which remained after the extraction was concentrated on the rotary evaporator. The test item and its degradation product chromatograms were obtained by liquid chromatography analysis with radio detector (LC-RAD-MS). These c
hromatograms were used for Kow estimation. In the HPLC method of OECD 117 guideline the chromatographic system with methanol water mobile phase without gradient elution is described. However, in the present study different chromatographic conditions were used because for the degradation product TP-1 reference substance is not available and therefore the low Kow measures were conducted with chromatographic conditions as in the OECD TG 309 study as follows: Individual solutions of a reference substances and solution of reference substances mixture were analysed with liquid chromatography method with UV detection. Based on the retention times of the compounds the Kow and log Kow value of the TP-1 was estimated. Reference samples used had log Kow ranging from 1.1-5.7.


Results: For the Kow determination according to the OECD 117 guideline dead-time (t0) needs to be measured with unretained organic substance for which usually formamide is used. For determination of dead-time solution of formamide was prepared at concentration of 0.5 g/L. In the chromatogram of formamide one small peak was observed after injection peak. For the prepared concentration a more abundant peak was expected, but it can be observed that injection peak was much more abundant then in the blank solution. Based on this chromatogram, formamide either eluted with the injection peak or a small peak after injection peak can be attributed to formamide. In the latter case the sensitivity of UV detection is poor with the employed mobile phase. Because the dead-time was not precisely determined Pow was calculated for all the options i.e. for both injection peaks (t0,1=1.25 min and t0,2=1.35 min), for the peak eluting after injection peak (t0,3=1.50 min) and for the calculated dead-time for the used column (t0,4=1.79 min). This means that a range of log Kows are presented and not a single point value. For the constituents of Cassiffix log Kows were derived ranging from 5 to 5.5. These will not be used for assessment because more reliable values from the slow stirring method are available. For TP-1 the log Kow ranged from 2.5 to 3 and the log Kow value will be used for further assessment.


Conclusion: The key degradation product of Cassiffix has a log Kow of 3, which is considered to be at the high end of the real log Kow.


An earlier study in which the Log Kow for Cassiffix was determined using shake flask method is removed because better and newer information is available. This former study resulted in a log Kow > 3.66 based on the shake-flask method (OECD TG 107).