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Partition coefficient

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partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
08 February 2013 - 1 May 2013
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was performed according to OECD and EEC guidelines and in compliance with GLP.
equivalent or similar to guideline
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
GLP compliance:
yes (incl. QA statement)
Certificate included in report
Type of method:
flask method
Partition coefficient type:
Analytical method:
other: UV/VIS spectroscopy
log Pow
Partition coefficient:
20 °C
>= 5.7 - <= 5.8
Details on results:
The detector calibration was found to be linear over the range 0 to 650 mg/L of standard solutions in water with a regression coefficient of 0.9999.
It had been anticipated that the test substance would not partition into the n-octanol phase and therefore the full scale spectra of the organic phases were assessed in order to verify that the absorbance was due to the enzyme. A typical spectrum is presented in the report and confirms the identity of the material in the n-octanol as Glucoamylase.
It was proposed that a reason for the presence of Glucoamylase in the n-octanol phases was due to water dissolved in the n-octanol causing the compound to occur in the organic phase. It was therefore regarded that the determined partition coefficient value represented a maximum value and the true partition coefficient was probably lower.
The accuracy of the analytical method was verified by the analysis of five replicate samples prepared at two concentrations: one at the level analysed for the aqueous phases (approximately 480 mg/L) and one at a level equivalent to a nominal limit of quantification (approximately 20 mg/L). The recoveries were 101% and 94%, respectively, and served to demonstrate the accuracy of the method.
The octanol/water partition coefficient of Glucoamylase was found to be < 0.05 (log10 Pow =< -1.3) at 20°C.
Executive summary:

A study was performed to determine the partition coefficient of the test substance, Glucoamylase, according to EEC Method A8 and OECD Method 107.

The study was conducted to comply with the requirements of European Council Directive for 91/414/EEC (Annex II) as amended by European Commission Directive 94/37/EC and amended by Commission Regulation (EU) No. 544/2011 Implementing Regulation (EC) Nov 1107/2009 of the European Parliament and of the Council as regards the data requirements for active substances.

The octanol/water partition coefficient of Glucoamylase was found to be < 0.05 (log10 Pow = < -1.3).

partition coefficient
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
other information
Justification for type of information:
Because all enzymes are built up of amino acids, the physical and chemical characteristics are very similar for different enzymes, and hence read-across from other enzymes should be fully applicable.The logPow value of the present target substance, arylesterase, has not been determined but other enzymes have been analyzed and the LogPow was found to be between (-3.1) – (-2.95) (ref. D. Basketter et al, 2012). These results are supported by read-across from a source substance, Glucoamylase. The conclusion is that the target substance arylesterase also has a low logPow value < -1.3.
- Basketter D., Berg N., Broekhuizen C., Fieldsend M., Kirkwood S., Kluin C., Mathieu S. and Rodriguez C. Enzymes in Cleaning Products: An Overview of Toxicological Properties and Risk Assessment/Management. 2012. Reg. Toxicol. Pharmacol, 64/1: 117-123
Partition coefficient type:

Description of key information

The octanol-water partition coefficient (logPow) for the test substance is <=-1.3 at 20 °C.

Key value for chemical safety assessment

Log Kow (Log Pow):
at the temperature of:
20 °C

Additional information