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Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

25 September 2020 to 19 November 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Deviations:

yes

Remarks:

The final composition of the reference item mix was 40.5 %THF/59.5 % aqueous phase instead of 40 %/60 %. This was considered uncritical because the difference is negligible (for comparison: the maximum allowed error of the used pipettes is 0.3 %).

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:

ca. 1.1 - ca. 9.95

Temp.:

25 °C

pH:

ca. 7

Remarks on result:

other:

Remarks:

The log KOW value of the test item X-21415 must be stated as < 1.1 - > 9.95. Calculation of a weighted mean value is not possible, because the log KOW values of a large percentage of the test item mass can only be extrapolated (C.p. details in paragraph "Any other information on results incl. tables")

The chromatograms of the test item gave 51 peaks distributed over 30 mass traces. With the calibration function log k versus log KOW, the corresponding log KOW values of the major peaks were calculated. The peaks were named according to the total number of carbon atoms in the side chains with suffixes “a”, “b” or “c” where different isomers were resolved.
Component	Mean Retention Time [min]		Mean Peak Area [counts*min]	Relative Peak area [%]			Log KOW ± Standard Deviation
C14	0.695		1357337	0.4			< 1.10
C16	0.719		107667883	30.5			< 1.10
C18	0.747		79161192	22.4			< 1.10
C20	0.786		45459065	12.9			< 1.10
C22	0.832		30777332	8.7			1.37 ± 0.000
C24a	0.752		92174	< 0.1			< 1.10
C24b	0.884		4033330	1.1			1.93 ± 0.000
C26a	0.793		122126	< 0.1			< 1.10
C26b	0.884		183718	< 0.1			1.93 ± 0.000
C28	0.845		201709	< 0.1			1.51 ± 0.074
C30a	0.886		18862	< 0.1			1.94 ± 0.033
C30b	1.038		184555	< 0.1		3.10 ± 0.113
C30c	1.081		229514	< 0.1		3.36 ± 0.019
C32a	1.118		9546787	2.7		3.56 ± 0.000
C32b	1.207		6932968	2.0		3.98 ± 0.018
C34a	1.239		13062896	3.7		4.12 ± 0.015
C34b	1.363		8134423	2.3		4.59 ± 0.014
C36a	1.386		12107151	3.4		4.67 ± 0.033
C36b	1.550		6196770	1.8		5.18 ± 0.021
C38a	1.564		9294014	2.6		5.21 ± 0.011
C38b	1.780		3882593	1.1		5.75 ± 0.015
C40a	1.241		57335	< 0.1		4.13 ± 0.027
C40b	1.780		4431731	1.3		5.75 ± 0.015
C40c	2.053		1678616	0.5		6.30 ± 0.012
C42a	1.382		44370	< 0.1		4.66 ± 0.033
C42b	2.038		1821782	0.5		6.27 ± 0.019
C42c	2.396		682146	0.2		6.86 ± 0.006
C44a	1.566		31887	< 0.1		5.22 ± 0.018
C44b	2.361		622870	0.2		6.81 ± 0.015
C44c	2.809		228170	< 0.1		7.40 ± 0.009
C46a	1.782		18464	< 0.1		5.75 ± 0.009
C46b	2.729		116411	< 0.1		7.31 ± 0.014
C46c	Not evaluated (only 2 peaks in 3 determinations)
C48a	2.865		291745	< 0.1		7.47 ± 0.015
C48b	3.249		100530	< 0.1		7.88 ± 0.017
C50a	3.364		565381	0.2		7.99 ± 0.022
C50b	3.829		165895	< 0.1		8.40 ± 0.014
C52a	3.931		704659	0.2		8.49 ± 0.027
C52b	4.550		156187	< 0.1		8.93 ± 0.011
C54a	4.618		659788	0.2		8.98 ± 0.042
C54b	5.384		122101	< 0.1		9.44 ± 0.002
C56a	5.367		525654	0.1		9.43 ± 0.029
C56b	6.396		77637	< 0.1		> 9.94 ± 0.010
C58	6.461		354312	0.1		> 9.95
C60	7.555		138663	< 0.1		> 9.95
C62	9.105		49118	< 0.1		> 9.95
C64	Not detectable
C66	10.479		137282	< 0.1		> 9.95
C68	12.062		199368	< 0.1		> 9.95
C70	Not evaluated (only 1 peak in 3 determinations)
C72	Not detectable

These values are the means ± standard deviations of three independent determinations

Peaks of components C14, C16, C18, C20, C24a and C26a eluted between the dead time marker and the first reference substance with a literature log KOW of 1.1. Therefore, the corresponding log KOW values should be stated as < 1.1 for these components. Peaks C58, C60, C62, C66 and C68 eluted after the last reference substance with a literature log KOW of 9.95. Therefore, the corresponding log KOW values should be stated as > 9.95.

Components C46c, C64, C70 and C72 were not detectable in at least one out of three inde-pendent determinations and were therefore not evaluated.

The peaks of components C14, C16, C18, C20, C24a and C26a correspond to a relative peak area of 66.3 %, The peaks of components C58, C60, C62, C66 and C68 correspond to a relative peak area of 0.2 %. The remaining peaks with log KOW values in the range 1.1 – 9.95 represent 33.4 % of the total peak area.

As a consequence, the log KOW value of the test item X-21415 must be stated as < 1.1 - > 9.95. Calculation of a weighted mean value is not possible, because the log KOW values of a large percentage of the test item mass can only be extrapolated.

Conclusions:

The log KOW value of the test item X-21415 must be stated as < 1.1 - > 9.95. Calculation of a weighted mean value is not possible, because the log KOW values of a large percentage of the test item mass can only be extrapolated.

Executive summary:

Peaks of components C14, C16, C18, C20, C24a and C26a eluted between the dead time marker and the first reference substance with a literature log KOW of 1.1. Therefore, the corresponding log KOW values should be stated as < 1.1 for these components. Peaks C58, C60, C62, C66 and C68 eluted after the last reference substance with a literature log KOW of 9.95. Therefore, the corresponding log KOW values should be stated as > 9.95.
Components C46c, C64, C70 and C72 were not detectable in at least one out of three independent determinations and were therefore not evaluated.
The peaks of components C14, C16, C18, C20, C24a and C26a correspond to a relative peak area of 66.3 %, the peaks of components C58, C60, C62, C66 and C68 correspond to a relative peak area of 0.2 %. The remaining peaks with log KOW values in the range 1.1 – 9.95 represent 33.4 % of the total peak area. As a consequence, the log KOW value of the test item X-21415 must be stated as < 1.1 – > 9.95. Calculation of a weighted mean value is not possible, because the log KOW values of a large percentage of the test item mass can only be extrapolated.
It was not possible to use a reference item with log KOW value < 1.1 because of interfering peaks at short retention times originating from the phenylalkane reference items. 

Description of key information

Log Kow was determined in OECD Guideline 117. The chromatograms of the test item gave 51 peaks distributed over 30 mass traces. The log KOW value of the test item X-21415 must be stated as < 1.1 –> 9.95. Calculation of a weighted mean value is not possible, because the log KOW values of a large percentage of the test item mass can only be extrapolated.