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vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
16 - 18 April, 1991
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP Study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 104 (Vapour Pressure Curve)
GLP compliance:
Type of method:
static method

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Unspecified example: C18.3H46.8O5.8Si4.1
Details on test material:
Identification: DC 5067
Description: Clear, light brown liquid
Lot Number: AB 090122
Purity: >99%
Storage conditions: In the original container at room temperature in the dark
Stability under storage conditions: Stab1e
Expiry date: December 1, 1991

Results and discussion

Vapour pressure
25 °C
Vapour pressure:
ca. 32 Pa
Remarks on result:
other: 29 - 35 Pa

Any other information on results incl. tables

The vapour pressure at 25°C was determined using the Static Technique. During the measurements 1-7 at 26.78°C, a relatively large decrease in vapour pressure could be observed. Therefore the sample was evacuated for 10 s after each measurement. This decrease in vapour pressure is probably caused by the presence of a volatile impurity. Because the sample was re-exposed to a fresh vacuum at the start of each measurement, the most volatile impurity was removed gradually. This impurity was removed after approximately 7 measurements, indicating that the amount of this impurity was relatively low. Therefore the 10 s evacuation step between the measurements was stopped. Although the vapour pressure was nearly stable at the end of the measurements, the test substance behaviour was not ideal. The consequence of this is that it is more difficult to determine "the vapour pressure" of the test substance because the composition of the vapour in the sample cell continuously changed. In order to obtain the vapour pressure at each temperature, the results of the vapour pressure readings were extrapolated (when necessary) to a theoretical initial measurement in each series. The results are shown in Table 1 below.

Measurements Temperature of measurement ln(p) (PA) Vapour pressure1)(Pa)
8 - 42  26.78  3.57  35.5 
43 - 93  32.71  3.93  51 
96 - 1032)  39.90  4 .27 +- 0.03  71.4 +- 2.1 

1): After extrapolation to the measurements of series 3

2): The vapour pressure was nearly stable

In order to obtain the vapour pressure, the results at each temperature were calculated relative to the vapour pressure measured at 38.90°C (see Table l), taking into account the vapour pressure rise caused by the rise in temperature.

Applicant's summary and conclusion

The vapour pressure of the main components in the test substance at 25°C was determined to be
P(25°C) = 32 +- 3Pa
= 0.24 +- 0.02 mm Hg
Executive summary:

The determination of the vapour pressure of DC 5067 was based on the following guidelines: European Economic Community (EEC),EEC directive 841449 EEC, Annex, Part A, Methods for the determination of physico-chemical properties, A.4: "Vapour pressuren, EEC Publication no. L251, September 1984 Organization for Economic Co-operation and Development (OECD), OECD guidelines for testing chemicals, Guideline No.104: *Vapour pressure curvew, adopted May 12, 1981. The vapour pressure curve was constructed using the determination of the vapour pressure of DC 5067 at 26.78, 32.71 and 38.90°C, using the Static Technique. The vapour pressure of DC 5067 at 25°C was extrapolated to be 32 Pa with an estimated error of +- 3 Pa, i.e. 0.24 +- 0.02 mm Hg.