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Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 January - 23 February 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

The study was conducted according to an internationally recognised method. Test substance is adequately characterised. Therefore full validation applies.

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Version / remarks:

2006

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

Version / remarks:

Commission Regulation (EC) No 761/2009 of 23. July 2009, published on 24. Aug. 2009

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Remarks:

inspected on 20 and 21 June 2017 / signed on 04 September 2017

Type of method:

static method

Key result

Temp.:

20 °C

Vapour pressure:

1 631 Pa

Temp.:

25 °C

Vapour pressure:

2 172 Pa

Temp.:

50 °C

Vapour pressure:

7 963 Pa

Individual results

20.5 g of the test item were filled into the measurement cell.

As the pressure didn’t increase or decrease during the first measurement phase, the apparatus was considered tight and no leak rate had to be taken into account.

The vapour pressure and system temperature respectively were measured at six temperature levels.

The vapour pressure was measured in the temperature range of 46 °C to 87 °C (the temperature range was chosen to preliminary information from DSC measurements (see melting/boiling point and explosive properties endpoints). The measured vapour pressures at the corresponding temperatures are listed in the table below.

Table 4.6/1.- Measured vapour pressures and corresponding temperatures

Temperature / °C	Vapour pressure / hPa
46.2	66.1
56.2	105.9
66.4	170.9
76.6	256.3
81.7	319.6
86.8	384.8

No measurement was performed at decreasing temperatures due to a slight drift at the highest temperatures indicating a starting change of the test item (e.g. decomposition). As the vapour pressures showed a very good behaviour over the temperature the measurement was evaluated as valid.

The vapour pressure (logarithmic scale) as a function of the inverse temperature (1/T, T in Kelvin) is repoted in the experimental report. Only for better readability the temperature is also reported in a centigrade scale. The values for 20, 25 and 50 °C are calculated, using the Antoine constants A, B and C as shown in table 4.6/2 below.

 

Table 6.4/2.- Antoine parameters and extrapolated vapour pressures

T / °C	p / hPa	log (p/hPa) = A + B/(C+T[°C])
20	16.3	A = 8.62968
25	21.7	B = -2174.35
50	79.6	C = 273.15

 

 

Final results

The following vapour pressure values for the test item were interpolated and extrapolated from the experimental data:

T / °C	p / hPa	p / Pa
20	16.3	1631
25	21.7	2172
50	79.6	7963

Conclusions:

The vapour pressure of the test item was calculated as 1631 Pa at 20.0 °C and 2172 Pa at 25 °C.
These values represent the component with the highest vapour pressure.

Executive summary:

The vapour pressure of the test substance was measured under GLP according to OECD 104 / EU A4 guideline, static method. 6 temperature/vapour pressure were used to calculate a regression in a temperature range of 46.2 – 86.8 °C,from which vapour pressure at ambient temperature could be estimated.

From the measured values, the vapour pressure of the test item was calculated as 1631 Pa at 20.0 °C and 2172 Pa at 25 °C.

These values represent the component with the highest vapour pressure.

Description of key information

The vapour pressure of the test item was calculated as 1631 Pa at 20.0 °C and 2172 Pa at 25 °C (extrapolation).  

These values represent the component with the highest vapour pressure.

Key value for chemical safety assessment

Vapour pressure:

1 631 Pa

at the temperature of:

20 °C

Additional information

A fully reliable experimental study, conducted according to a recognized OECD/EC method and under GLP, is available. Therefore, it is considered as a key study, and the result is retained as key data for purpose of CSA.