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Physical & Chemical properties

Vapour pressure

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Administrative data

Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
21 October 1996 - 9 January 1997
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: done under GLP and OECD method

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report Date:
1997

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: Directive 92/69/EEC, Method A4, Vapour pressure balance method.
Principles of method if other than guideline:
The vapour pressure was determined using a vapour pressure balance based on a CI Electronics micro-balance with a sensitivity of approximately
D 1 µg. The temperature of the sample was controlled electronically
(+/-1°Cl over the range ambient to 250°C. The mass readings and temperature were recorded directly onto a 2 channel chart recorder.

The construction of the vapour pressure balance is shown in figure 1. On opening the slide across the orifice in the temperature controlled evaporation furnace. the escaping vapour jet was directed at the scale
pan. The vapour pressure was determined directly from the pressure on the scale pan by measuring the difference of mass readings when the slide across the orifice was open and closed and also when efficient
condensation occurs from the rate of the latter onto the pan. The vapour
pressure of the sample was measured at several temperatures to yield vapour pressure curves for subsequent extrapolation to give 298.15K values.
GLP compliance:
yes
Type of method:
effusion method: vapour pressure balance

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
Appearance: White Powder
Date recieved: 2 October 1996

Results and discussion

Vapour pressure
Temp.:
10.6 °C
Vapour pressure:
0 Pa
Remarks on result:
other: First vapour pressure

Any other information on results incl. tables

The vapour pressure of Test Material UK-143.108 was determined on the 8- 9" January 1997 using the vapour pressure balance. The solid sample was maintained below 195.5°C during experiments and showed no signs of melting or decomposition. The sample condensed onto the balance pan at the highest temperatures (see Section 4.2) and some data were corrected for this. The substance melting point is 205°C. The initial measured mass difference of Run 1 was 0.24µg at 10.6°C (equivalent to about 3.1 X io Pascals) with values rising to a maximum of 190µg (equivalent to around 2.5 X 101 Pascals) at 194°C. Condensation was Gbserved at and above 78.0°C. Run l measured mass difference data gave a distorted vapour pressure relationship (see graphical plot of Run 1) and were not pursued further. After pumping during recooling overnight. the initial measured mass differ nce of Run 2 was 0.4µg at 33.6cC (equivalent to about 5.2 X ioPascals) with values rising ultimately to 153µg at 195.25°C and increasing to beyond 250µg at around the same temperature after some 5 minutes. Condens2tion was observed at and above 156.0°C. Run 2 measured mass difference data gave a distorted vapour pressure relationship (see graphical plot of Run 2) but the corrected data segment (Run 2A) yielded the rounded value VpC25°Cl = 4.1 +3.5/-2.0 x io12 Pascals as the extrapolated vapour pressure.

Applicant's summary and conclusion

Conclusions:
After pumping during recooling overnight. the initial measured mass differ nce of Run 2 was 0.4µg at 33.6 c (equivalent to about 5.2 X 10^-4
Pascals) with values rising ultimately to 1 3µg at 195.25°C and increasing to beyond 250µg at around the same temperature after some 5 minutes. Condensation was observed at and above 156.0°C .' Run 2 measured mass difference data gave a distorted vapour pressure relationship (see graphical plot of Run 2) but the corrected data segment (Run 2A) yielded the rounded value

Vp(25°C) = 4.1 +3.5/-2.0 X 10^12 Pascals as the extrapolated vapour pressure.