Poly(oxy-1,2-ethanediyl), α-[2-(dide- cylmethylammonio)ethyl]- .omega.- hydroxy-, propanoate (salt) (Bardap 26)

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Data waiving:

study technically not feasible

Justification for data waiving:

the study does not need to be conducted because the substance has a high surface activity

Description of key information

In accordance with column 2 of REACH Annex VII, the partition coefficient n-octanol/water study (required in section 7.8) cannot be performed as  the substance has a high surface activity.  The physical/chemical nature of N,N-Didecyl-N-methyl-poly(oxyethyl)ammonium Propionate (surface active properties and high solubility in octanol and water) does not allow for experimental determination of the log Kow. The determination of partition coefficient is not possible by Method A8 of Commission Directive 92/69/based on the following: N,N-Didecyl-N-methyl-poly(oxyethyl)ammonium Propionate exhibits the properties of a surfactant in the octanol/water system, thus preventing the use of the shake-flask method. Estimation by the HPLC Method is not valid either due to the absence of suitable calibration compounds and since ionic compounds interact with the HPLC column by forces other than partitioning. The generator column method is not useful because the high water solubility does not provide for sufficient retention of N,N-Didecyl-N-methyl-poly(oxyethyl)ammonium Propionate on the column. The ratio of the solubility of N,N-Didecyl-N-methyl-poly(oxyethyl)ammonium Propionate in n-octanol and water is also not a valid estimate due to the self-aggregation properties of surfactants. N,N-Didecyl-N-methyl-poly(oxyethyl)ammonium Propionate possesses the chemical structure of a typical surfactant (i.e. long carbon chains with a polar head). The surfactant properties have been further confirmed by the surface tension result (30.5 mN/m); a reading of less than 60 mN/m is considered to be an indicator of surfactant properties.  An alternative to experimental testing of partition coefficient is to provide an assessment of partition coefficient by computer-based estimation software. However, on assessing the validity of this model, it was deemed that this approach also was unsuitable for N,N-Didecyl-N-methyl-poly(oxyethyl)ammonium Propionate. Since the program used (KOWWIN) estimates the partition coefficient based on a fragment contribution method, the prediction was considered inaccurate. The software fragment values from the alkyl chains predominantly override the values from the nitrogen and CH3atoms. The predicted value for the dialkylammonium ion (the environmental ion of interest) was considered an overestimate based on its high solubility in water. Furthermore, experience and use of the software has shown that there are no similar reference compounds to N,N-Didecyl-N-methyl-poly(oxyethyl)ammonium Propionate which could be used for validation purposes. The software database is very limited for surface active materials since these cannot be readily measured by experimental techniques as discussed above.  In conclusion, no value for partition coefficient has been or can be experimentally determined or modeled. N,N-Didecyl-N-methyl-poly(oxyethyl)ammonium Propionate is essentially miscible in water and octanol (see Document IIIA Sections 3.5 and 3.7(1). Therefore, the best estimate of a partition coefficient, is 1 (log Kow = 0). The principle value of the partition coefficient is in the estimation of potential bioaccumulation in the environment. The potential for N,N-Didecyl-N-methyl-poly(oxyethyl)ammonium Propionate to bioaccumulate is low based on experimental studies (Document IIIA – Section 7.4.3.3.1). Therefore, the lack of a measured partition coefficient is not important to the environmental risk assessment of N,N-Didecyl-N-methyl-poly(oxyethyl)ammonium Propionate.

Key value for chemical safety assessment

Log Kow (Log Pow):

0

at the temperature of:

20 °C