7-methyl-3-methyleneocta-1,6-diene

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

7 January 2012 - 12 March 2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Well described study conducted according to A8 method and OECD guideline 117 without any deviation.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(13 April 2004)

Deviations:

no

GLP compliance:

no

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

4.82

Temp.:

30 °C

pH:

ca. 6.5

Remarks on result:

other: +/- 0.01

Reference items:

Retention times and capacity factors

The retention times of the reference items and calculated capacity factors are presented in the following table.

Compound	tR1(min)	tR2(min)	Mean (min)	Standard deviation (min)	Relative standard deviation	k
Benzene	3.79	3.79	3.79	0.00	0.00%	0.48
Trichloroethylene	4.47	4.49	4.48	0.01	0.32%	0.75
Toluene	4.81	4.82	4.82	0.01	0.15%	0.88
M-Xylene	6.62	6.63	6.63	0.01	0.11%	1.58
1,2,4-trimethylbenzene	9.21	9.22	9.22	0.01	0.08%	2.59
Benfuracarb	10.43	10.47	10.45	0.03	0.27%	3.00
Butralin	19.59	19.61	19.60	0.01	0.07%	6.64
Heptachlor	27.37	27.37	27.37	0.00	0.00%	9.67

The relative standard deviations of the retention times of the reference items laid all below 0.4%.

Dead times t₀:

- 2.58 and 2.59 min (HPLC analysis of reference items mix)

- 2.59 and 2.59 min (HPLC analysis of Benfuracarb).

The mean value is used for calculation of k.

log Pow/log k

log Pow (literature data) and calculated log k of the reference items are presented in the following table.

Compound	log k	log Pow
Benzene	-0.32	2.13
Trichloroethylene	-0.13	2.40
Toluene	-0.06	2.69
M-Xylene	0.20	3.16
1,2,4-trimethylbenzene	0.41	3.65
Benfuracarb	0.48	4.22
Butralin	0.82	4.93
Heptachlor	0.99	5.44

log k versus log Pow and Correlation Results

The logarithms of the mean capacity factors, log k, are plotted as a function of log Pow and the linear regression equation is obtained as follows :

log k = (0.380 x log Pow) - 1.062

with a coefficient of determination r2 = 0.986

MYRCENE

Retention times and capacity factors

The retention times of the test item are presented in the following table.

	tR1(min)	tR2(min)	tR3(min)	Mean (min)	Relative standard deviation
Test item	17.83	17.81	17.82	17.82	0.06%
Dead time	2.56	2.57	2.57	2.57	0.22%

log Pow/log k

Log Pow is calculated using the regression equation obtained from the reference items.

Capacity factor k, log k and log Pow for the test item are presented in the following table.

Measurement No.	k	log k	log Pow
1	5.96	0.78	4.83
2	5.93	0.77	4.82
3	5.93	0.77	4.82
Mean			4.82
Standard deviation			0.01

Results obtained with another HPLC Column

The retention times and capacity factors of the reference items obtained with a different C18 bonding are presented in the table below.

Compound	tR(min)	k	log k
Benzene	4.09	0.83	-0.08
Trichloroethylene	5.13	1.30	0.11
Toluene	5.63	1.52	0.18
M-Xylene	8.35	2.74	0.44
1,2,4-trimethylbenzene	12.19	4.47	0.65
Benfuracarb	20.17	8.04	0.91
Butralin	37.29	15.72	1.20
Heptachlor	47.55	20.32	1.31

The linear regression of the plot log k versus log Pow gives the following equation:

log k = (0.425 x log Pow) – 0.931

with a coefficient of determination r² = 0.992

The retention time of the test item was 31.11 min, corresponding to a log k of 11. According to the previous equation, the log Pow can be estimated to 4.81 with this column.

This result is not significantly different from the one obtained previously (4.82). It can be concluded that a change in the C18 silica bonding chemistry has no significant effects on log Pow results.

Conclusions:

Using the HPLC method, log Pow of MYRCENE was determined to be 4.82 ± 0.01

Executive summary:

The partition coefficient of MYRCENE was determined at 30°C by HPLC method according to EU Method A.8 and OECD Guideline No 117:

log Pow = 4.82 ± 0.01 (Mean retention time: 17.82 min). This value was the mean ± standard deviation of three independent determinations.

Calibration was appropriately performed between 2.13 and 5.44, in buffered mobile phase at pH=6.5, with 8 references substances; these reference items were chosen in relation to the expected retention time of the test item. For each reference item, two determinations were performed. The capacity factor k was calculated from the retention time of acetone (dead time) and the retention time of the respective reference item. A calibration function (log k versus log Pow, linear fit) was determined based on literature values of Pow for the reference items. Despite the purity of the reference substances was missing, the regression equation shows a good linearity. The correlation between log k and log Pow was satisfactory according to the coefficient of determination r² of 0.986. This value was considered as sufficiently high to use the calibration function for the determination of the log Pow of MYRCENE. Variations in the retention times of reference items and test item were very small. Therefore a stable configuration of the HPLC-column can be assumed.

A second measurement was carried out on another C18 silica column and gave similar results.

As no observations were made which might cause doubts concerning the validity of the study outcome, the study was considered as reliable without restrictions.

Description of key information

A study was conducted to determine the partition coefficient of myrcene according to OECD Guideline 117, HPLC method.
Three consecutive measurements were performed at 30°C. 
The log Pow value for myrcene has been determined to be 4.82 ± 0.001.

Key value for chemical safety assessment

Log Kow (Log Pow):

4.82

at the temperature of:

30 °C

Additional information

Well described key study was conducted without any deviation according to OECD guideline 117. A mean value was claculated to give a representative estimation of the partition coefficient of myrcene.

The value was considered with a reliability of 2 (reliable with restrictions) because the result is scientifically acceptable but not obtained under GLP and some details were lacking in the report.

However, the result may be used as end point value for the partition coefficient and was confirmed by two supporting studies.