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Vapour pressure

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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:
OECD Guideline 104 (Vapour Pressure Curve)
Version / remarks:
2006
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.4 (Vapour Pressure)
Version / remarks:
2009
Deviations:
no
GLP compliance:
yes (incl. certificate)
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 r2

0.993570239

 

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

P(20 °C) = 10B * (1/293.15) + A 

P(25 °C) = 10B * (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).