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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - Shake Flask Method)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Other quality assurance:
ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
Type of method:
flask method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
Identification: Hydroxypropyl, 2-, trimethylammonium formate
Other name: Solvent-free Dabco TMR-2
Physical state/appearance: colorless to very light blue liquid
Batch: chernil.20160628.B
CAS Number: 62314-25-4
EU Number: 263-503-6
Purity: 95.25% active in water
Expiry date: 28 June 2017
Storage conditions: Room temperature in the dark, over silica gel
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
< 0.01
Temp.:
22.5 °C
pH:
5
Conclusions:
The partition coefficient (Pow) of the test item, monitoring the hydroxypropyl, 2-,trimethylammonium content of the test item, has been determined to be less than 1.00 x 10-2, log10 Pow <-2.00, at a nominal pH value of 5 (actual value 5.0 to 5.1) and a test temperature of 22.5 ± 0.5 °C.
Executive summary:

The partition coefficient of salts is required within the environmentally relevant pH range of5 to 9 at which the theoretical solubility is maximized in n-octanol and therefore the value ofpartition coefficient is maximized. As the quaternary amine retains a permanent cationiccharge irrespective of pH, evaluation of the test system pH was therefore limited to theformic acid content of the test item.Based on a literature dissociation constant value of 3.75 for the carboxylic acid functionalgroup of formic acid (Haynes, W M (editor), CRC Handbook of Chemistry and Physics, 94thEdition, CRC Press, 2013), the test system was buffered to a nominal pH of 5 and thepartitioning characteristics of the major component (the hydroxypropyl, 2-,trimethylammonium content of the test item) was monitored and quantified by HPLC-MS.On analysis of the organic phases, no quantifiable responses were obtained for any of the sixphases analyzed, with all responses being less than that obtained for the lowest concentrationcalibration standard solution. Therefore a limit value has been used for the organic phaseconcentrations during the calculation of the partition coefficient for this test item component.The limit value selected was less than a concentration of 0.5 mg/L, which represented thenominal concentration of the duplicate QC standards analyzed during calibration of theHPLC-MS instrument and was also approximately ten times the maximum response obtainedfrom any of the organic phases. On correcting this limit value for the dilution factoremployed for the analysis of organic phases (10), an actual limit value of <5.0 mg/L wasachieved. The use of a limit value in no way impacted on the validity of the study since itstill confirmed the partition coefficient of the quaternary amine cation as being log Pow<-2.00, which is the lower domain limit of the regulatory method used.

Description of key information

log Pow was found to be less than 1.0 x 10-2`at 22.5 ± 0.5 °C,log10Pow<-2.00, monitoring the hydroxypropyl, 2-, trimethylammonium content of the testitem, at a nominal pH value of 5 (actual value 5.0 to 5.1).

Key value for chemical safety assessment

Log Kow (Log Pow):
0.01
at the temperature of:
22.5 °C

Additional information