Essential oil of Cistus ladaniferus L (Cistaceae) obtained from stems and leaves by distillation

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

8 Novembre 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

The study was conducted according to an internationally recognised method, and under GLP. No deviation was reported. Test substance is adequately specified. Therefore full validation applies.

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Version / remarks:

2006

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

Version / remarks:

2009

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

GLP certificate (inspected on 13 to 14 Octher 2014 / signed on 8 April 2015)

Type of method:

static method

Key result

Test no.:

#1

Temp.:

ca. 20 °C

Vapour pressure:

ca. 1 356 Pa

Key result

Test no.:

#2

Temp.:

ca. 25 °C

Vapour pressure:

ca. 1 697 Pa

The calculation results are presented in the following table:

Table 4.6/1.- Calculated values for 1/T and log P

n	Temperature T	Pressure P	Temperature T	1/T	log P
	°C	hPa*	K	1/K	log Pa
1	20.0	12.7	293.15	0.00341122	3.1038
2	27.5	18.4	300.65	0.00332613	3.2648
3	35.3	27.2	308.45	0.00324202	3.4346
4	44.1	40.2	317.25	0.00315209	3.6042
5	49.8	47.0	322.95	0.00309645	3.6721
6	55.0	52.0	328.15	0.00304739	3.7160
7	47.8	42.8	320.95	0.00311575	3.6314
8	41.9	35.5	315.05	0.00317410	3.5502
9	33.1	24.3	306.25	0.00326531	3.3856
10	26.0	17.8	299.15	0.00334280	3.2504
11	20.1	14.2	293.25	0.00341006	3.1523
12	15.1	10.7	288.25	0.00346921	3.0294

*hPa = mbar

The parameters for the linear regression of the graph log (p) vs. 1/T are presented in the following table:

Table 4.6/2.-Linear Regression Parameters

Parameter	Value
Slope	-1704.379779
Intercept	8.946268726
Correlation coefficient r	-0.996779935
Coefficient of determination r^2	0.993570239

 

Using the equations below, vapour pressures at ambient temperature were calculated.

P(20 °C) = 10^{B * (1/293.15) + A} 

P(25 °C) = 10^{B * (1/298.15) + A}

Table 4.6/3.- Calculated Values for vapour pressure

Parameter	Value	Unit
Vapour Pressure (20 °C)	1356	Pa
Vapour Pressure (25 °C)	1697	Pa

Discussion

The vapour pressure of the test item was measured using the static method as described in EU method A.4. Twelve pairs temperature/vapour pressure were used to calculate a regression from which vapour pressure at ambient temperature could be estimated.

From the measured values, the vapour pressure of the test item was calculated as 1356 Pa at 20.0 °C and 1697 Pa at 25 °C. The values of the heating and cooling down phase showed very good correspondence.

Therefore, the result of the study is considered valid.

Conclusions:

The vapor pressure of the test substance has been determined to be 1356 Pa at 20 °C and 1697 Pa at 25 °C.

Executive summary:

The vapour pressure of the test substance was measured under GLP according to OECD 104 / EU A4 guideline using the static method.

12 individual measurements of vapour pressure were conducted in a temperature range of 15.1 – 55.0 °C and the pairs of Temperature / Vapour pressure were used to calculate a regression from which vapour pressure at ambient temperature could be interpolated.

Finally, the vapor pressure of the test substance has been determined to be 1356 Pa at 20 °C and 1697 Pa at 25 °C.

Note that the result obtained on this kind of substance should be largely influence by small amounts of volatile constituents and these values don't represent the major part of the substance. Therefore the result should be considered with caution when used for subsequent assessment (worst case).

Description of key information

The vapor pressure of the test substance has been determined to be 1356 Pa at 20 °C and 1697 Pa at 25 °C (interpolation).

Key value for chemical safety assessment

Vapour pressure:

1 356 Pa

at the temperature of:

20 °C

Additional information

A reliable experimental study, conducted according to a recognized OECD/EC method and under GLP, is available. It is considered as a key study.

Note that the result obtained on this kind of substance should be largely influence by small amounts of volatile constituents and these values don't represent the major part of the substance. Therefore the result should be considered with caution when used for subsequent assessment (worst case).