2,2'-azobis[4-methoxy-2,4-dimethylvaleronitrile]

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

27.07.-28.07.16

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)

Version / remarks:

2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

2.3

Temp.:

25 °C

Remarks on result:

other: HPLC screening; pH not determined

Capacity factor, log Capacity Factor, log Pow test item peaks

Peak	Measurement No.	K	log K	log POW
1	1	0.6984	-0.1559	1.133
	2	0.6968	-0.1569	1.131
	3	0.6977	-0.1563	1.132
	Mean			1.132
	Standard Deviation			0.001
2	1	2.1164	0.3256	2.273
	2	2.1154	0.3254	2.273
	3	2.1165	0.3256	2.274
	Mean			2.273
	Standard Deviation			0.000
3	1	2.5204	0.4015	2.453
	2	2.5202	0.4014	2.453
	3	2.5173	0.4009	2.452
	Mean			2.453
	Standard Deviation			0.001
4	1	4.7732	0.6788	3.110
	2	4.7691	0.6784	3.109
	3	4.7800	0.6794	3.111
	Mean			3.110
	Standard Deviation			0.001

Conclusions:

Variations in the retention times of reference items and test item are very small. Therefore a stable configuration of the HPLC-column can be assumed.
The correlation log K/log POW is good: the coefficient of determination r2 was calculated with 0.9582. This value was considered as sufficiently high to use the calibration function for the de-termination of the log POW of the test item 2,2'-Azobis (4-methoxy-2,4-dimethyl valeronitrile).
As peaks 1, 3 and 4 showed a relative area < 5 %, they were considered as minor peaks. Alt-hough area is not necessarily correlated to absolute concentration if UV detection is used, it is assumed that the test item 2,2'-Azobis (4-methoxy-2,4-dimethyl valeronitrile) consists mainly of the second peak, indicating that the log POW should be regarded as 2.3.
No observations were made which might cause doubts concerning the validity of the study outcome.

Executive summary:

The study was performed using a HPLC with a C18 column. Seven 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 P_OWare 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/water 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 P_OW, linear fit) was determined using the literature values for P_OWof the reference items and the retention times in the six determinations.

 

The chromatogram of the test item gave one major and three minor peaks. With the calibration function log K versus log P_OW, the corresponding log P_OWs of the major peaks were determined with:

Peak	Mean Area [mAU*min][1]	Relative Area [%]	Mean Retention Time [min]	log POW ±Standard Deviation
1	0.151	1.24	2.319	1.1 ± 0.0
2	10.917	89.65	4.257	2.3 ± 0.0
3	0.161	1.32	4.808	2.5 ± 0.0
4	0.292	2.40	7.888	3.1 ± 0.0

[1]mAU = milli absorbance units

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

As peaks 1, 3 and 4 showed a relative area < 5 %, they were considered as minor peaks. Although area is not necessarily correlated to absolute concentration if UV detection is used, it is assumed that the test item2,2'-Azobis (4-methoxy-2,4-dimethyl valeronitrile) consists mainly of the second peak, indicating that the log P_OWshould be regarded as 2.3.

Description of key information

Based on the findings in the available guideline study the value of 2.3 is selected as key value for the further chemical safety assessment.

Key value for chemical safety assessment

Log Kow (Log Pow):

2.3

at the temperature of:

25 °C