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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:
29-05-2017 to 07-06-2018
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: July 2017 ; signature: November 2017
Type of method:
gas saturation method
Temp.:
20 °C
Vapour pressure:
0.75 Pa
Temp.:
25 °C
Vapour pressure:
0.987 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]

A

25

3.49 x10^4

3.08 x10^3

5.83

3.08 x10^3

1.13

0.975 ± 0.162

B

4.52 x10^4

2.85 x10^3

8.02

2.86 x10^3

0.806

C

5.86 x10^4

4.55 x10^3

6.63

4.55 x10^3

0.991

A

35

3.37 x10^4

4.33 x10^3

4.53

4.33 x10^3

1.70

1.75 ± 0.114

B

4.31 x10^4

5.44 x10^3

4.15

5.45 x10^3

1.67

C

5.61 x10^4

7.98 x10^3

7.61

7.99 x10^3

1.88

A

45

3.48 x10^4

6.47 x10^3

3.61

6.47 x10^3

2.53

2.66 ± 0.200

B

4.51 x10^4

9.58 x10^3

5.11

9.58 x10^3

2.89

C

5.87 x10^4

1.10 x10^4

7.66

1.11 x10^4

2.56

*: 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 0.987 Pa.

The linearity of the detector response with respect to concentration was assessed over the concentration range of 10.0 to 1.0 x10^3 mg/L (n=7). This was satisfactory with a correlation coefficient of ≥ 0.99 being obtained.

Conclusions:
The vapour pressure of the test item was determined to be 0.750 Pa at 20°C (293K) and 0.987 Pa at 25°C (298K), respectively.
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 item under the conditions of the test. The mean vapour pressure was 25°C: 0.975 Pa;  35°C: 1.75 Pa and 45°C: 2.66 Pa, respectively. The vapour pressure of the test item was interpolated from the vapour pressure curve (ln Pvp versus 1/T) and was determined to be 0.750 Pa at 20°C (293K) and 0.987 Pa at 25°C (298K).

Description of key information

Vapour Pressure: 0.987 Pa at 25 °C, EU Method A.4 - Gas Saturation Method, 2018

Key value for chemical safety assessment

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

Additional information

Key study : EU Method A.4, 2018 : 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 item under the conditions of the test. The mean vapour pressure was 25°C: 0.975 Pa;  35°C: 1.75 Pa and 45°C: 2.66 Pa, respectively. The vapour pressure of the test item was interpolated from the vapour pressure curve (ln Pvp versus 1/T) and was determined to be 0.750 Pa at 20°C (293K) and 0.987 Pa at 25°C (298K).