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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:
2000-10-13
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Version / remarks:
OECD Guideline No. 117, adopted on 30th March 1989.
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
Version / remarks:
Commission Directive No. 92/69/EEC, A.8, 31 July 1992 (HPLC method)
Deviations:
no
GLP compliance:
yes
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
2.82
Temp.:
23 °C
Remarks on result:
other: pH value not reported



Evaluation of k’ and Pow


The capacity factor k' was calculated from the dead time to and retention times according to the


equation:


 


k' = (tr-t0) / t0


to: HPLC dead time (min)


tr: HPLC retention time of test and reference substances (min)


 


The log k’ data of the reference substances were then plotted against their log Pow values from


batch equilibrium given in table 2. Using this plot, the Pow values determined for the reference


substances were within ± 0.5 log units of the values determined by the batch equilibrium method


in the OECD guideline and the log k’ value of the test substance was then used to determine its


log Pow value. The values of the Pow taken from the duplicate analyses were within the range of


0.1  log units.


 


Determination of dead time (t0)


Formamide, t0 = 1.19 min


Determination of the retention time (tr)


Nitrobenzene, tr = 5.50 min


Methyl benzoate, tr = 7.50 min


Ethyl benzoate , tr = 14.0 min


Toluene, tr = 17.8 min


1,4 Dichlorobenzene, tr = 38.8 min


Test item, tr = 18.7 min


Evaluation of k’ and log k'


Nitrobenzene, k’ = 3.61 log k' = 0.558


Methyl benzoate, k’ = 5.29 log k' = 0.724


Ethyl benzoate, k’ = 10.7 log k' = 1.03


Toluene, k’ = 13.9 log k'- 1.14


1,4 Dichlorobenzene, k’ = 31.5 log k'- 1.50


Test item, k’ = 14.7 log k'- 1.17


 


Evaluation of Pow: log Pow = 2.82 ± 0.01


Linear least squares regression: a = 1.58, b = 0.971, r2 = 0.99.

Conclusions:
The partition coefficient of the test item was determined to be 2.82 at 23 °C.
Executive summary:



The partition coefficient (Pow) of the test item was estimated according to the test guidelines described in Commission Directive 92/69/EEC, A.8, 31 July 1992 and OECD Guideline for Testing of Chemicals No. 117 "Partition Coefficient (n-octanol/water), High Performance Liquid Chromatography (HPLC) Method". Therefore, HPLC was performed on a Symmetry Cl8 column packed with solid phase containing long hydrocarbon chains chemically bound onto silica. The test substance was eluted along the column by partitioning between the mobile solvent phase and the hydrocarbon stationary phase. The test substance was retained in proportion to its hydrocarbon-water partition coefficient. Using reference substances a relationship between the retention time on a reverse-phase column and the n-octanol/water partition coefficient was established. The value of the partition coefficient was determined to be 2.82 at 23 °C.

Description of key information



The partition coefficient of the test item was determined to be 2.82 at 23 °C (reference 4.7-1).

Key value for chemical safety assessment

Log Kow (Log Pow):
2.82
at the temperature of:
23 °C

Additional information



The partition coefficient (Pow) of the test item was estimated according to the test guidelines described in Commission Directive 92/69/EEC, A.8, 31 July 1992 and OECD Guideline for Testing of Chemicals No. 117 "Partition Coefficient (n-octanol/water), High Performance Liquid Chromatography (HPLC) Method". Therefore, HPLC was performed on a Symmetry Cl8 column packed with solid phase containing long hydrocarbon chains chemically bound onto silica. The test substance was eluted along the column by partitioning between the mobile solvent phase and the hydrocarbon stationary phase. The test substance was retained in proportion to its hydrocarbon-water partition coefficient. Using reference substances a relationship between the retention time on a reverse-phase column and the n-octanol/water partition coefficient was established. The value of the partition coefficient was determined to be 2.82 at 23 °C (reference 4.7-1).