2-(2,6-diethyl-4-methyl-phenyl)propanediamide

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

26 November 2003 to 01 December 2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7550 (Partition Coefficient, n-octanol / H2O, Shake Flask Method)

Deviations:

no

GLP compliance:

yes

Type of method:

shake-flask method to: flask method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

Pow

Partition coefficient:

14

Temp.:

25 °C

pH:

5

Type:

log Pow

Partition coefficient:

1.2

Temp.:

25 °C

pH:

5

Type:

Pow

Partition coefficient:

14

Temp.:

25 °C

pH:

7

Type:

log Pow

Partition coefficient:

1.1

Temp.:

25 °C

pH:

7

Type:

Pow

Partition coefficient:

13

Temp.:

25 °C

pH:

9

Type:

log Pow

Partition coefficient:

1.1

Temp.:

25 °C

pH:

9

Details on results:

Following centrifugation, the equilibrium concentrations of the test item in either the two clear separated phases were all less than 2483 mg/L i.e. less than 0.01 molar.
The individual log Pow values of all six samples varied between 1.14 to 1.17 for the citrate buffer, 1.12 and 1.15 for the phosphate buffer and 1.10 and 1.16 for the borax buffer solutions. All were found to be within the range of ± 0.3 log units.

Table 1: Results with buffer solution pH 5

Sample number	P1	P2	P3	P4	P5	P6
Amount of test material (mg)	30.3088	29.2121	62.3125	60.2188	14.8553	16.1514
Volume of octanol (mL)	20	20	40	40	10	10
Volume of water (mL)	20	20	20	20	20	20
Concentration of the test material in the octanol phase (mg/L)	1469.220	1423.408	1542.763	1545.409	1423.382	1471.300
	1471.972	1401.249	1593.563	1490.749	1422.459	1453.813
Average concentration:	1470.596	1412.329	1568.163	1518.079	1422.921	1462.557
Concentration of the test material in the aqueous phase (mg/L)	103.054	100.832	111.355	106.919	96.386	105.439
	102.307	102.122	111.304	106.649	96.465	102.957
Average concentration:	102.681	101.477	111.330	106.784	96.426	104.198
pH of aqueous phase	4.97	4.97	4.97	4.97	4.97	4.98
Average pH of aqueous phase	5.00
Amount of test material in the octanol phase (mg)	29.4119	28.2466	62.7265	60.7232	14.2292	16.6256
Amount of test material in the aqueous phase (mg)	2.0536	2.0295	2.2266	2.1357	19.2850	2.0840
Total amount of test material in the two phases (mg)	31.4655	30.2761	64.9531	62.8589	16.1577	16.7096
Recovery (%)	104	104	104	104	109	103
Pow	14.32	13.92	14.09	14.22	14.76	14.04
Average Pow	14.12		14.16		14.40
Average Pow ± standard deviation	14 ± 0.30
Log Pow	1.2

 

Table 2: Results with buffer solution pH 7

Sample number	P1	P2	P3	P4	P5	P6
Amount of test material (mg)	23.7286	23.4295	29.4115	30.8073	18.9430	18.8433
Volume of octanol (mL)	20	20	40	40	10	10
Volume of water (mL)	20	20	20	20	20	20
Concentration of the test material in the octanol phase (mg/L)	1127.954	1123.905	728.501	764.207	1637.202	1644.009
	1155.229	1103.739	726.507	774.955	1658.220	1688.024
Average concentration:	1141.592	1113.822	727.504	769.581	1648.711	1666.017
Concentration of the test material in the aqueous phase (mg/L)	82.254	78.122	53.768	55.310	119.415	127.703
	81.653	78.659	54.392	55.124	117.680	124.929
Average concentration:	81.954	78.391	54.080	55.217	118.548	126.316
pH of aqueous phase	6.99	6.99	7.00	7.00	7.00	6.99
Average pH of aqueous phase	7.00
Amount of test material in the octanol phase (mg)	22.8318	22.2764	29.1002	30.7832	16.4871	16.6602
Amount of test material in the aqueous phase (mg)	1.6391	1.5678	1.0816	1.1043	2.3710	2.5263
Total amount of test material in the two phases (mg)	24.4709	23.8442	30.1818	31.8875	18.8581	19.1865
Recovery (%)	103	102	103	104	100	102
Pow	13.93	14.21	13.45	13.94	13.91	13.19
Average Pow	14.07		13.70		13.55
Average Pow ± standard deviation	14 ± 0.38
Log Pow	1.1

 

Table 3: Results with buffer solution pH 9

Sample number	P1	P2	P3	P4	P5	P6
Amount of test material (mg)	29.0127	28.8133	30.1094	31.2061	27.9160	28.2151
Volume of octanol (mL)	20	20	40	40	10	10
Volume of water (mL)	20	20	20	20	20	20
Concentration of the test material in the octanol phase (mg/L)	1427.103	1402.427	747.179	716.648	2324.970	2434.682
	1410.997	1395.177	738.297	716.165	2356.201	2413.251
Average concentration:	1419.050	1398.802	742.738	716.407	2340.586	2423.967
Concentration of the test material in the aqueous phase (mg/L)	102.778	97.631	55.312	57.700	175.047	180.058
	101.749	96.936	56.789	56.281	177.874	185.136
Average concentration:	102.264	97.284	56.051	56.991	176.461	182.597
pH of aqueous phase	9.04	9.05	9.05	9.04	9.04	9.04
Average pH of aqueous phase	9.00
Amount of test material in the octanol phase (mg)	28.3810	27.9760	29.7095	28.6563	23.4059	24.2397
Amount of test material in the aqueous phase (mg)	2.0456	1.9457	1.1210	1.1398	3.5292	3.6519
Total amount of test material in the two phases (mg)	30.4263	29.9217	30.8305	29.7961	26.9351	27.8916
Recovery (%)	105.0	104.0	102.0	95.5	96.5	98.9
Pow	13.88	14.38	13.25	12.57	13.26	13.27
Average Pow	14.13		12.91		13.27
Average Pow ± standard deviation	13 ± 0.62
Log Pow	1.1

 

Conclusions:

Under the conditions of the test, the partition coefficients of the test material at 25 °C was Pow 14 (± 0.30), 14 (± 0.38) and 13 (± 0.62) for buffer solutions at pH5, pH7 and pH 9 respectively. The respective log Pow values were 1.2, 1.1 and 1.1. The study is considered to be reliable, relevant and adequate for risk assessment and classification and labelling purposes.

Executive summary:

The octanol/water partition coefficient of the test material was determined in accordance with the standardised guidelines OECD 107, EU Method A.8 and EPA OPPTS 830.7550 using the shake flask method. Under the conditions of the test the partition coefficients of the test material at 25 °C were P_ow 14 (± 0.30), 14 (± 0.38) and 13 (± 0.62) for buffers solutions at pH 5 (citrate buffer), pH 7 (phosphate buffer) and pH 9 (borate buffer) respectively. The respective log P_ow values were 1.2, 1.1 and 1.1.

Description of key information

Log Pow 1.1 (Pow 14), at 25 °C and pH 7, OECD TG 107, Das 2003a

Key value for chemical safety assessment

Log Kow (Log Pow):

1.1

at the temperature of:

25 °C

Additional information

The octanol/water partition coefficient of the test material was determined in two studies in accordance with the standardised guidelines OECD 107, EU Method A.8 and EPA OPPTS 830.7550. In the key study (Das 2003a), using the shake flask method with buffered solutions, the partition coefficients of the test substance at 25 °C were P_ow 14 (± 0.30), 14 (± 0.38) and 13 (± 0.62) for buffers solutions at pH 5 (citrate buffer), pH 7 (phosphate buffer) and pH 9 (borate buffer) respectively. The respective log P_ow values were 1.2, 1.1 and 1.1. In the supporting study (Das 2003b), the octanol/water partition coefficient was determined to be P_ow 8.6 (± 0.14) (log P_ow 0.93) at 25 °C, using the same guidelines (non-buffered solutions).

The partition coefficient does not vary greatly between the different testing approaches and overall indicate the same property of the test material. Both studies were reported to a high standard, performed in compliance with GLP and to standardised guidelines. The results from the shake flask method are selected as the key value because there are a direct measurement of the octanol-water partitioning, and the more conservative result. Although, none of the standardised tests for partition coefficient are considered suitable for surface active materials (slow-stirring is considered the most appropriate test), the two studies examine the partition coefficient at different pHs and demonstrate little difference in the partitioning coefficients in each test. Both studies were assigned a reliability score of Klimisch 1 and as such were considered suitable for use as an accurate reflection of the test substance.

The available data are considered to be complete and the result determined, log Pow 1.1 (Pow 14), at 25 °C and pH 7, was taken forward for risk assessment.