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Vapour pressure

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vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to guideline
EU Method A.4 (Vapour Pressure)
according to guideline
OECD Guideline 104 (Vapour Pressure Curve)
GLP compliance:
Type of method:
static method
20 °C
Vapour pressure:
1.2 Pa
Remarks on result:
other: + / - 0.1 Pa

At the beginning of the test, the vapour pressure of the test substance decreased slightly every next measurement, due to the removal of volatile impurities. After measurement 20, this decrease became negligible and the vapour pressure was stable. So from that moment on, the collected data were used for the final result.

For each temperature, a selected number of measurements was used for the calculations:

 Measurement  Temperature [°C]  Mean vapour pressure ln(p)  Mean vapour pressure [Pa]
 24 - 65  38.82  2.59 +/- 0.01  13.3 +/- 0.2
 80 - 104  31.77  1.77 +/- 0.02  5.85 +/- 0.09
 122 - 156  24.72  0.88 +/- 0.02  2.25 +/- 0.05

Fitting these data according to Clark & Glew gives a value of 1.21 Pa (+/- 0.12 Pa) = 9.0E-03 mm Hg (+/- 0.7E-03 mm Hg) for the vapour pressure of test substance at 20 °C.

Description of key information

1.2 Pa at 20 °C

(EU Method A.4, static method)

Key value for chemical safety assessment

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

Additional information

The vapour pressure of sodium 2-biphenylate (hydrated form) was determined by static method according EU Method A.4 to be 1.2 Pa at 20 °C. In a supporting thermogravimetric study the test substance did not show a detectable vapour pressure at a temperature between 20 and 70 °C. A mass-reduction of the sample in a temperature range of 52 - 62 °C is caused by the removal of crystal water.

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