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Vapour pressure

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Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
not conducted in compliance with GLP regulation but according to guideline. Data are comprehensive and scientifically acceptable but only limited documentation is available.
Qualifier:
according to guideline
Guideline:
other: ASTM D2879 method
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
no
GLP compliance:
no
Type of method:
isoteniscope
Temp.:
20 °C
Vapour pressure:
4 052 Pa
Remarks on result:
other: Calculated value using the Antoine equation
Key result
Temp.:
25 °C
Vapour pressure:
4 430 Pa
Remarks on result:
other: Calculated value using the Antoine equation
Temp.:
50 °C
Vapour pressure:
6 467 Pa
Remarks on result:
other: Calculated value using the Antoine equation

Measured data

Temperature

[°F]

Temperature

[°C]

Pressure

[Torr]

Pressure

[Pa]

-30

-34,44

7.2

960

-15

-26,11

9.3

1234

0

-17,77

12.0

1600

15

-9,44

15.5

2066

30

-1,11

19.0

2533

40

4,44

--

--

45

7,22

23

3066

60

15,55

28

3733

75

23,8

34

4533

Regression analysis

Input parameter

Modified units

Calculation

Correlated

Deviation squared

Parameter of the Antoine equation

p (mbar)

T (C)

p (Pa)

T (K)

ln(p)

(ln(p)-

ln(pvg))2

ln(p)

(ln(pexp)

-ln(pcor))2

9.6

-34.4

960.00

238.7

6.87

0.67

6.83

0.00

A =

11.41

12.34

-26.1

1234.00

247.0

7.12

0.33

7.14

0.00

C =

-124.08

16

-17.8

1600.00

255.4

7.38

0.10

7.41

0.00

B =

524.44

20.66

-9.4

2066.00

263.7

7.63

0.00

7.65

0.00

 

 

25.33

-1.1

2533.00

272.0

7.84

0.02

7.86

0.00

 

 

30.66

7.2

3066.00

280.4

8.03

0.12

8.05

0.00

 

 

37.33

15.6

3733.00

288.7

8.22

0.29

8.22

0.00

 

 

45.33

23.8

4533.00

297.0

8.42

0.53

8.38

0.00

 

 

 

 

 

 

7.69

2.06

 

0.01

 

 

 

 

 

 

 

 

R² =

0.996682888

 

 

 

Conclusions:
The vapour pressure was calculated to be 40.52 hPa at 20 °C, 44.3 hPa at 25 °C and 64.67 hPa at 50 °C respectively.
Executive summary:

The determination of the vapour pressure of the test item (25 % minieral spirit as stabiliser) was performed (Phoenix Chemical Laboratory, Inc; 1992) according to the Regulation (EC) 440/2008 Part A, A.4 "vapour pressure" and the ASTM D2879-97 "Standard Test Method for Vapour Pressure-temperature Relationship and Initial decomposition Temperature of Liquids by Isoteniscope." (1997). Therefore the vapour pressure was measured in the temperature range of -34.4 to 23.8 °C. From the measured data points of the vapour pressure curve the constants A, B and C of the Antoine equation was derived by regression of the data points. The vapour pressure was calculated by extrapolation of the measured vapour pressure curve for the temperatures 20, 25 and 50 °C to be 40.52 hPa, 44.3 hPa and 64.67 hPa respectively. No observations were made which might cause doubts concerning the validity of the study outcome.

Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2000-01-21
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
non GLP, only limited documentation available
Qualifier:
equivalent or similar to guideline
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
not specified
Principles of method if other than guideline:
The pressure is measured accurately with an electronic micro membrane manometer. The vacuum DSC experiments were carried out at various controlled pressure levels. Approximately 15 mg is weighed into a 70 micro litre aluminium cup with a pierced lid. After reaching a constant pressure, the DSC temperature scan is started. The heating rate is 5°C/min. During this scan, the product will evaporate. A sudden increase in the endothermic heat flow is then obtained. This represents the initial boiling point of the mixture at the pre-set pressure. A condenser, cooled by CO2 ice extrudates, captures the gases. After at least 4 DSC scans at different pressures, a plot is constructed with 10log p (p: mbar) versus T(K), the Antoine plot of the product.
GLP compliance:
no
Type of method:
other: differential scanning calorimeter
Temp.:
20 °C
Vapour pressure:
1.71 Pa
Remarks on result:
other: Calculated value using the Antoine equation
Key result
Temp.:
25 °C
Vapour pressure:
1.966 Pa
Remarks on result:
other: Calculated value using the Antoine equation
Temp.:
50 °C
Vapour pressure:
3.72 Pa
Remarks on result:
other: Calculated value using the Antoine equation

The vapour pressure was measured in range from 36 -67 °C. From the measured data points of the vapour pressure curve the constants A, B and C of the Antoine equation was derived by regression (Microsoft Excel) of the data points to

 

A = 9.75

B = 2991.10

C = 31.46

 

The vapour pressure of the test item was calculated by extrapolation of the measured vapour pressure curve for the temperatures 20, 25 and 50 °C, according to Regulation EC 440/2008 Method A.4.

Conclusions:
The vapour pressure was calculated to be 1.71 Pa at 20 °C, 1.966 Pa at 25 °C and 3.72 Pa at 50 °C respectively.
Executive summary:

The determination of the vapour pressure of the test item (50% isododecane as stabiliser) was performed (AKZO Nobel; 2000) similar to the Regulation (EC) 440/2008 Part A, A.4 "vapour pressure". Therefore the vapour pressure was measured by DSC ((differential scanning calorimeter) in the temperature range of 36 to 67 °C. From the measured data points of the vapour pressure curve the constants A, B and C of the Antoine equation was derived by regression of the data points. The vapour pressure was calculated by extrapolation of the measured vapour pressure curve for the temperatures 20, 25 and 50 °C to be 1.71 Pa, 1.966 Pa and 3.72 Pa respectively. No observations were made which might cause doubts concerning the validity of the study outcome.

Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
1991-08-21
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
not conducted in compliance with GLP regulation but data are comprehensive and scientifically acceptable.
Qualifier:
equivalent or similar to guideline
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
not specified
Principles of method if other than guideline:
A sample of about 15 mg is weighed into a high Aluminium pan, the pan is closed by a cover provided with a 1 mm pinhole. The pan is placed into the DSC cell, the cell is evacuated till the desired absolute pressure and heated up with a rate of 5°C/min. The sample evaporates very fast above its boiling point, this will be recorded as a fast increase in the endothermal effect. A next test is carried out at an other pressure; in this way it is possible to establish the saturated vapour pressure as a function of temperature.
GLP compliance:
no
Type of method:
other: differential scanning calorimetry
Key result
Temp.:
20 °C
Vapour pressure:
360 Pa

Description of key information

There are three Studies available:

Key study:

The vapour pressure was calculated to be 1.71 Pa at 20 °C, 1.966 Pa at 25 °C and 3.72 Pa at 50 °C respectively.

Supporting studies:

The vapour pressure was calculated to be 40.52 hPa at 20 °C, 44.3 hPa at 25 °C and 64.67 hPa at 50 °C respectively.

The vapour pressure was calculated to be 360 Pa at 20°C.

Key value for chemical safety assessment

Vapour pressure:
1.966 Pa
at the temperature of:
25 °C

Additional information

Key study

The determination of the vapour pressure of the test item (50% isododecane as stabiliser) was performed (AKZO Nobel; 2000) similar to the Regulation (EC) 440/2008 Part A, A.4 "vapour pressure". Therefore the vapour pressure was measured by DSC ((differential scanning calorimeter) in the temperature range of 36 to 67 °C. From the measured data points of the vapour pressure curve the constants A, B and C of the Antoine equation was derived by regression of the data points. The vapour pressure was calculated by extrapolation of the measured vapour pressure curve for the temperatures 20, 25 and 50 °C to be 1.71 Pa, 1.966 Pa and 3.72 Pa respectively. No observations were made which might cause doubts concerning the validity of the study outcome.

supporting studies

The determination of the vapour pressure of the test item (25 % mineral spirit as stabiliser) was performed (Phoenix Chemical Laboratory, Inc; 1992) according to the Regulation (EC) 440/2008 Part A, A.4 "vapour pressure" and the ASTM D2879-97 "Standard Test Method for Vapour Pressure-temperature Relationship and Initial decomposition Temperature of Liquids by Isoteniscope." (1997). Therefore the vapour pressure was measured in the temperature range of -34.4 to 23.8 °C. From the measured data points of the vapour pressure curve the constants A, B and C of the Antoine equation was derived by regression of the data points. The vapour pressure was calculated by extrapolation of the measured vapour pressure curve for the temperatures 20, 25 and 50 °C to be 40.52 hPa, 44.3 hPa and 64.67 hPa respectively. No observations were made which might cause doubts concerning the validity of the study outcome.

The determination of the vapour pressure of the test item (50% isododecane as stabiliser) was performed (AKZO Nobel; 1991) similar to the Regulation (EC) 440/2008 Part A, A.4 "vapour pressure". Therefore the vapour pressure was measured by DSC ((differential scanning calorimeter) in the temperature range of 20 to 180 °C. Vapour pressure of pure test item was calculated accoring to Dalton and Racult's lax, assuming ideal gas-liquid behaviour, using the experimental data of the test item and the literature data of isododecane. The calcualted vapour pressure is 360 Pa at 20 °C. The accuracy of this result is low because small deviations in the measured data give a big deviation in teh calculated vapour pressure.