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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:
2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study performed under GLP. All relevant validity criteria were met.
Qualifier:
according to
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
inspected: June 2015; signature: September 2015
Type of method:
gas saturation method
Temp.:
25 °C
Vapour pressure:
0.168 Pa

Calculation of the Vapour Pressure

The vapour pressure at a given temperature can be calculated by determining the amount of material transported by a known amount of carrier gas. Volume correction was completed by appropriate calculation methods described in the study report. The Vapour pressure was subsequently calculated from:

Pvp = W x R x T / V x M

Pvp = vapour pressure [Pa] (calculated)

W = mass of evaporated test item [micro-grams] (from analysis)

R = gas constant = 8.314 J/K mol

T = temperature [K] (measured)

V = volume of nitrogen at test temperature [mL] (determined from flow rate)

M = molar mass of test item

 

From experimental data performed at the three test temperatures, the vapour pressure of the test item at 25 °C was calculated by interpolation of ln vapour pressure versus the reciprocal of test temperature (K).

 

The mass of transferred test item and corresponding vapour pressures are shown in the following table:

Saturator Column

Temp. [°C]

Volume*
V [mL]

Mass of Test Item in Trap 1 [µg]

Mass of Test Item in Trap 2 [µg] #

Total Mass of Test Item [µg]

Vapour Pressure [Pa]

Average Vapour Pressure [Pa]

(Std Dev)

A

25

178792

2208

0

2208

0.159

0.167

 

(6.92 x 10-3)

B

238389

3196

0

3196

0.173

C

297986

3889

0

3889

0.168

A

35

84170

3289

0

3289

0.521

0.524

 

(2.90 x 10-2)

B

112227

4188

0

4188

0.497

C

140284

5843

0

5843

0.555

A

45

142041

14913

0

14913

1.44

1.46

 

(1.32 x 10-2)

B

189387

20036

0

20036

1.46

C

236734

25306

0

25306

1.47

*: Corrected volume at test temperature as calculated under "Volume correction"

#: 0 µg refers to non-detected within trap 2

A, B and C refers to three different flow rates respectively, reported in the full study report.

 

The vapour pressure at 25 °C was interpolated from the vapour pressure curve (ln Pvp versus 1/T) and was calculated to 0.168 Pa.

The linearity of the detector response with respect to concentration was assessed over the concentration range of 44.2 to 506 mg/L. This was satisfactory with a correlation coefficient of ≥ 0.999 being obtained.

Conclusions:
The vapour pressure of the test substance has been determined to be 0.168 Pa at 25 °C.
Executive summary:

The vapour pressure was determined using EU Method A.4 and OECD TG 104 using the gas saturation method under GLP. To ensure saturation control, three different flow rates were used at each temperature. In the determination higher flow rates did not lead to lower vapour pressures, which means that the nitrogen was saturated with test substance under the conditions of the test. The mean vapour pressure was 25°C: 0.168 Pa;  35°C: 0.524 Pa and 45°C: 1.46 Pa respectively. The vapour pressure of the test substance was interpolated from the vapour pressure curve (ln Pvp versus 1/T) and was calculated to be 0.168 Pa at 25°C.

Description of key information

Vapour Pressure: 0.168 Pa at 25 °C, EU Method A.4 - Gas Saturation Method, 2017

Key value for chemical safety assessment

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

Additional information

Key study: EU Method A.4, 2017 : The vapour pressure was determined using EU Method A.4 and OECD TG 104 using the gas saturation method under GLP. To ensure saturation control, three different flow rates were used at each temperature. In the determination higher flow rates did not lead to lower vapour pressures, which means that the nitrogen was saturated with test substance under the conditions of the test. The mean vapour pressure was 25°C: 0.168 Pa;  35°C: 0.524 Pa and 45°C: 1.46 Pa respectively. The vapour pressure of the test substance was extrapolated from the vapour pressure curve (ln Pvp versus 1/T) and was calculated to be 0.168 Pa at 25°C.