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Vapour pressure

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Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
22 January 2018 - 24 January 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method A.4 (Vapour Pressure)
Version / remarks:
2009
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Version / remarks:
2006
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 830.7950 (Vapor Pressure)
Version / remarks:
1996
Deviations:
no
GLP compliance:
yes
Type of method:
effusion method: isothermal thermogravimetry
Specific details on test material used for the study:
The test material contains a high percentage of water.
Key result
Temp.:
20 °C
Vapour pressure:
0 Pa
Remarks on result:
other: the result is for the solid, water-free part of the substance
Key result
Temp.:
25 °C
Vapour pressure:
0 Pa
Remarks on result:
other: the result is for the solid, water-free part of the substance

Table: Results of the isothermal TGA analysis (test item)

Temperature
[°C]

Weight loss
[µg/min]

vT
[g/cm^2/h]

log vT

log PT

PT
[Pa]

170

1.40921

1.68E-4

-3.77

0.31

2.0

 

1.36845

1.63E-4

-3.79

0.29

1.9

180

2.39999

2.86E-4

-3.54

0.60

4.0

 

1.99323

2.38E-4

-3.62

0.50

3.2

190

3.76536

4.49E-4

-3.35

0.85

7.1

 

3.29527

3.93E-4

-3.41

0.78

6.0

200

5.25331

6.27E-4

-3.20

1.04

11

 

4.93191

5.89E-4

-3.23

1.00

10

Conclusions:
Using the isothermal thermogravimetric effusion method, the vapour pressure of the solid, water-free part of the substance was determined to be 2.6E-6 Pa and 5.0E-6 Pa at 20°C and 25°C, resp.
Executive summary:

The vapour pressure of the substance was determined using the isothermal thermogravimetric effusion method in a GLP study according to EC A.4, OECD 104 and OPPTS 830.7950. Validation of the method was performed using a set of five reference substances. Since the test substance contained a high percentage of water, the measurements were performed at temperatures > 100°C to allow the water to evaporate before measuring weight loss as a function of time. Weight losses of the test substance were measured at 170°C, 180°C, 190°C and 200°C. The experiments were performed in duplicate. From all results, the vapour pressure regression curve (log PT as a function of 1/T; with T in K) was constructed. The vapour pressure of the solid, water-free part of the substance was calculated (extrapolated) from the vapour pressure curve to be 2.6E-6 Pa and 5.0E-6 Pa at 20°C and 25°C, resp.  

Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
15 January 2018 - 18 January 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method A.4 (Vapour Pressure)
Version / remarks:
2009
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Version / remarks:
2006
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 830.7950 (Vapor Pressure)
Version / remarks:
1996
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
effusion method: isothermal thermogravimetry
Specific details on test material used for the study:
The test material contained a high percentage of water.
Key result
Temp.:
20 °C
Vapour pressure:
>= 0 - <= 0 Pa
Remarks on result:
other: the result is for the water-free (solid) part of the substance
Key result
Temp.:
25 °C
Vapour pressure:
>= 0 - <= 0 Pa
Remarks on result:
other: the result is for the water-free (solid) part of the substance

Table: Results of the isothermal TGA analysis (test item)

Experiment

Temperature
[°C]

Weight loss
[µg/min]

vT
[g/cm^2/h]

log vT

log PT

PT [Pa]

1

150

0.877960

1.05E-4

-3.98

0.04

1.1

 

160

2.10438

2.51E-4

-3.60

0.53

3.4

 

170

4.46611

5.33E-4

-3.27

0.95

8.9

 

180

7.00794

8.37E-4

-3.08

1.20

16

2

150

2.04788

2.44E-4

-3.61

0.51

3.3

 

160

3.05548

3.65E-4

-3.44

0.74

5.4

 

170

6.80963

8.13E-4

-3.09

1.18

15

 

180

10.4522

1.25E-3

-2.90

1.42

26

3

150

0.957379

1.14E-4

-3.94

0.09

1.2

 

160

2.39968

2.86E-4

-3.54

0.60

4.0

 

170

4.79000

5.72E-4

-3.24

0.99

9.7

 

180

7.67946

9.17E-4

-3.04

1.25

18

 

Table: vapour pressure results for each of the three tests

Test no.

Temp. [°C]

Vapour pressure [Pa]

1

20

1.8E-8

 

25

4.9E-8

2

20

1.3E-6

 

25

3.0E-6

3

20

2.4E-8

 

25

6.3E-8

 

Conclusions:
The vapour pressure at 20°C of the solid, water-free part of the substance was determined to be in the range from 1.8E-8 to 1.3E-6 Pa.
The vapour pressure at 25°C of the solid, water-free part of the substance was determined to be in the range from 4.9E-8 to 3.0E-6 Pa.
Executive summary:

The vapour pressure of the substance was determined using the isothermal thermogravimetric effusion method in a GLP study according to EC A.4, OECD 104 and OPPTS 830.7950. The constants specific for the experimental arrangement were determined using a set of five reference substances. Since the substance contained a high percentage of water,the measurements were performed at temperatures > 100°C to allow the water to evaporate before measuring weight loss as a function of time. Weight losses of the substance were measured at 150°C, 160°C, 170°C and 180°C. Three experiments were performed. As only coefficients of correlations > 0.99 were obtained for vapour pressure curves obtained from data of each of the three individual experiments, three vapour pressure regression curves (log PT as a function of 1/T) of the substance were constructed.Vapour pressure values of the substance at 20°C and 25°C were calculated from each of the three vapour pressure regression curves by extrapolation, and reported as a range.

The vapour pressure at 20°C of the solid, water-free part of the substance was determined to be in the range from 1.8E-8 to 1.3E-6 Pa.  

The vapour pressure at 25°C of the solid, water-free part of the substance was determined to be in the range from 4.9E-8 to 3.0E-6 Pa.

Description of key information

The vapour pressure of two substances representative for the registered substance was determined using the isothermal thermogravimetric effusion method in GLP studies according to EC A.4, OECD 104 and OPPTS 830.7950.

Key value for chemical safety assessment

Vapour pressure:
0 Pa
at the temperature of:
20 °C

Additional information

The vapour pressure at 20°C of the first solid (water-free part of the substance) was determined to be in the range from 1.8E-8 to 1.3E-6 Pa. The second solid (water-free part of the substance) was found to have a vapour pressure of 2.6E-6 Pa at 20°C. The highest value was used as key value for the risk assessment.