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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:
20/01/2016 - 11/05/2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Qualifier:
according to guideline
Guideline:
EU Method A.4 (Vapour Pressure)
GLP compliance:
yes (incl. QA statement)
Type of method:
effusion method: vapour pressure balance
Specific details on test material used for the study:
- Name of test material (as cited in study report): 1,1-Dimethylharnstoff, N,N-Dimethylharnstoff
- Physical state: solid

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: AlzChem AG, Batch 534201
- Expiration date of the lot/batch: 31/12/2017
- Purity test date:17/12/2015

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Ambient temperature (10-30 °C), dry, protected from light

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: The test item was tested as received. No further preliminary treatment such as drying or milling was performed.
Temp.:
20 °C
Vapour pressure:
0.004 Pa
Key result
Temp.:
25 °C
Vapour pressure:
0.008 Pa
Temp.:
50 °C
Vapour pressure:
0.13 Pa

The vapour pressure was measured in the temperature range of 30 °C to 80 °C. The measured vapour pressures at the corresponding temperatures are listed in Table 1.

Table1: Measured vapour pressures and corresponding temperatures

Temperature / °C

Vapour pressure / hPa

30

1.6 × 10-4

40

4.2 × 10-4

50

1.3 × 10-3

60

3.8 × 10-3

70

1.0 × 10-2

80

2.2 × 10-2

The values for 20, 25 and 50 °C are calculated, using the Antoine constants A, B and C as shown in Table 2.

Table 2: Antoine parameters and extrapolated vapour pressures

T / °C

p / hPa

log (p/hPa) = A + B/(C+T[°C])

20

4.4×10-5

A =

11.61755

25

8.2×10-5

B =

-4682.45

50

1.3×10-3

C =

273.15

Conclusions:
The following vapour pressure values for the test substance 1,1-Dimethylurea were extrapolated from the experimental data:
Vapour Pressure (20 °C) = 4.4 x 10^-3 Pa
Vapour Pressure (25 °C) = 8.2 x 10^-5 Pa
Vapour Pressure (50 °C) = 1.3 x 10^-1 Pa
Executive summary:

The purpose of this study was the determination of the vapour pressure of the test substance 1,1 -Dimethylurea according to OECD 104 ("Vapour Pressure") and EU Method A.4. ("Vapour pressure: Effusion method"). The method is based on the estimation of the mass of the test item following out per unit of time of a Knudsen cell in form of vapour, through a micro-orificr under ultra-vacuum conditions.

The following vapour pressure values for the test substance 1,1-Dimethylurea were extrapolated from the experimental data:

Vapour Pressure (20 °C) = 4.4 x 10^-3 Pa

Vapour Pressure (25 °C) = 8.2 x 10^-5 Pa

Vapour Pressure (50 °C) = 1.3 x 10^-1 Pa

Description of key information

The purpose of this study was the determination of the vapour pressure of the test substance 1,1 -Dimethylurea according to OECD 104 ("Vapour Pressure") and EU Method A.4. ("Vapour pressure: Effusion method"). The method is based on the estimation of the mass of the test item following out per unit of time of a Knudsen cell in form of vapour, through a micro-orificr under ultra-vacuum conditions.

The following vapour pressure values for the test substance 1,1-Dimethylurea were extrapolated from the experimental data:

Vapour Pressure (20 °C) = 4.4 x 10^-3 Pa

Vapour Pressure (25 °C) = 8.2 x 10^-5 Pa

Vapour Pressure (50 °C) = 1.3 x 10^-1 Pa

Key value for chemical safety assessment

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

Additional information