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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:
10. April 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Guideline study as required by REACH regulation 1907/2006
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Version / remarks:
OECD Guidelines for the Testing of Chemicals, Method No. 117, adopted 13. April 2004: “Partition Coefficient (n-octanol/water), High Performance Liquid Chromatog-raphy (HPLC) Method“
Deviations:
yes
Remarks:
The reference items were dissolved in methanol / water 65 / 35 (%, v/v) instead of methanol / 25 mM phosphate buffer pH 7 65 / 35 (%, v/v) like the test item.
Qualifier:
according to
Guideline:
other: EU Method A. 24
Version / remarks:
Commission Regulation (EU) 2016/266 of adopted 7 December 2015 amending Regu-lation EC No. 440/2008, Method A.24 “Partition Coefficient (N-OCTANOL/WATER), HIGH PERFORMANCELIQUID CHROMATOGRAPHY (HPLC) METHOD
Deviations:
yes
Remarks:
The reference items were dissolved in methanol / water 65 / 35 (%, v/v) instead of methanol / 25 mM phosphate buffer pH 7 65 / 35 (%, v/v) like the test item.
Principles of method if other than guideline:
Corresponding SOP of LAUS GmbH : SOP 118 009 30 “Bestimmung des log POW (Verteilungskoeffizient n-Octanol/Wasser) mittels HPLC“, edition 7, adopted 18. Sep. 2017

GLP compliance:
yes (incl. certificate)
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Batch No: 06386
- Expiration date of the lot/batch: June 2020
- Purity test date: July 2017
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
< 0.3
Temp.:
25 °C
pH:
>= 5 - <= 6
Details on results:
The correlation log k / log POW was used for the calculation of the log POW of the components of the test item. Due to the fact that the calculated log PO/W of the test item peak was lower than the lowest log PO/W of the reference items (2-Butanone with log POW 0.3) the log POW of this peak is stated as < 0.3.
Conclusions:
The correlation log k / log POW was used for the calculation of the log POW of the components of the test item. Due to the fact that the calculated log PO/W of the test item peak was lower than the lowest log PO/W of the reference items (2-Butanone with log POW 0.3) the log POW of this peak is stated as < 0.3.
Executive summary:

The study was performed to determine the log PO/Wof the test item using the HPLC method according to OECD 117 resp. EU A.24.

The study was performed using a HPLC with a C18 column. Six reference items with different retention times and thiourea for the determination of the dead time were used to produce a calibration curve, since retention time on hydrophobic columns and POWare correlated. The reference items were chosen based on the results of the pre-test.
One vial was filled with the reference item mix and one vial with the test item solution. The vials were analysed using the HPLC with the program described below. First one injection from the solvent blank methanol/25 mM phosphate buffer pH 7 65/35 (v/v) was made. Then three injections were measured from the reference item mix, three injections from the test item and again three injections from the reference item mix.
For each reference item, the capacity factor k was calculated from the retention time of thiourea and the retention time of the respective reference item.

A calibration function (log k versus log PO/W, linear fit) was determined using the literature values for PO/Wof the reference items and the retention times in the six determinations.

The test item showed one peak with a retention time 1.52 min with a very low standard deviation of 0.002 min. This peak lay not within the range of log PO/W’s of the reference items. The retention time of the test item peak was lower than the retention time of 2‑Butanone (1.857 min), the reference item with the lowest log POW, therefore a correct calculation is not possible. Therefore, the log PO/Wof the test item is stated as < 0.3. 


Description of key information

Determination of the Log P O/W by using the HPLC method according to OECD 117 resp. EU A.24

Key value for chemical safety assessment

Additional information

The peak of the test item lays not within the range of log POW’s of the reference items. The retention time of the test item peak was lower than the retention time of 2‑Butanone (1.857 min), the reference item with the lowest log POW, therefore a correct calculation is not possible. Therefore, the log POWof the test item is stated as < 0.3.