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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:
11 July - 20 July 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
effusion method: Knudsen cell
Specific details on test material used for the study:
- Test material: Balsalazide acid
- Batch number: 0400
- Expiry date: April 2019
- Storage: Room temperature
Key result
Temp.:
20 °C
Vapour pressure:
0 Pa

Since the analysis was conducted under high vacuum conditions, the heat could be transferred only by radiation, this caused a consistent difference between the furnace temperature and the sample one and a considerable time for the system to reach equilibrium.

The temperatures reported (registered by the thermocouple under the Knudsen cell) are hence different from the one set and the mass loss has been measured only in a 80 minutes time interval within each isotherm, after the system had reached equilibrium.

The first seven isotherms were discharged since the mass loss was too low to be accurate.

Table 1: Vapour pressure

Temperature

(°C)

Δm

(mg)

Δt

(min)

Temperature

(K)

125.3

0.0368

80

398.45

134.3

0.0507

80

407.45

143.4

0.0574

80

416.55

152.4

0.0931

80

425.55

161.5

0.1945

80

434.65

1/Temperature

(1/K)

Δm/Δt

(kg/s)

Vapour pressure

(Pa)

Log p

2.51E-03

7.67E-12

4.43E-02

-1.3539

2.45E-03

1.06E-11

6.17E-02

-1.2099

2.40E-03

1.20E-11

7.06E-02

-1.1512

2.35E-03

1.94E-11

1.16E-01

-0.9365

2.30E-03

4.05E-11

2.44E-01

-0.6119

y=mx+q

Parameterm

(slope)

Parameterq

(intercept)

ParameterR2

(correlation)

-3341

7

0.91558

Extrapolation at 20°C

1/Temperature

(1/K)

Log p

Vapour pressure

(Pa)

0.00341

-4.4206

3.80E-05

 

Conclusions:
The vapour pressure of Balsalazide acid is estimated to be 3.80E-05 Pa (2.85E-07 mmHg) at 20°C.

Description of key information

The vapour pressure of the test item, Balsalazide acid was determined according to OECD Guideline 104 and EC Method A.4 and was estimated to be 3.80E-05 Pa at 20°C.

Key value for chemical safety assessment

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

Additional information