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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:
From 04 June to 10 July 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Deviations:
not specified
Qualifier:
according to
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
not specified
GLP compliance:
yes (incl. certificate)
Type of method:
effusion method: by loss of weight or by trapping vaporisate
Test material information:
Composition 1
Key result
Temp.:
ca. 20 °C
Vapour pressure:
ca. 0 Pa
Key result
Temp.:
ca. 25 °C
Vapour pressure:
ca. 0 Pa

Results:   

The mass of sample in the respective cell is presented in the following table:

Parameter

Cell empty

Cell + test item

Cell + test item + cap

Test item

Unit

g

g

g

g

Knudsen-cell 1

2.58775

3.14483

3.39341

0.55708

Knudsen-cell 2

2.57872

3.08412

3.32713

0.50540

Knudsen-cell 3

2.61015

3.14597

3.39075

0.53582

Knudsen-cell 4

2.62388

3.17814

3.42128

0.55426

Experiments 1 - 5 (nominal temperatures 30, 45, 60, 75, and 90 °C) showed no significant and/or reproducible weight loss. In experiment 9 (nominal temperature 150 °C), the test item showed signs of decomposition and irreproducible weight loss. Therefore, these experiments were not included in the evaluation and the measured data are not included in this report. They will be stored together with the other raw data of the study under GLP conditions.

The data of the evaluated experiments is presented in the following tables:

Measurement Data Experiment 6:

Experiment

6

 

 

 

Nom. Temperature

105°C

 

 

 

Date and time START

 

28.June 2012 14:45

29.June 2012 14:50

30.June 2012 10:05

Date and time END

 

29.June 2012 13:45

30.June 2012 09:15

01.July 2012 08:30

Parameter

Weight m

Weight m

Weight m

Weight m

Unit

g

g

g

g

Knudsen-cell 1

3.38904

3.38795

3.38731

3.38686

Knudsen-cell 2

3.32305

3.32208

3.32156

3.32108

Knudsen-cell 3

3.38659

3.38568

3.38522

3.38466

Knudsen-cell 4

3.41665

3.41562

3.41480

3.41452

Measurement Data Experiment 7:

Experiment

7

 

 

 

Nom. Temperature

120°C

 

 

 

Date and time START

 

01.July 2012 09:30

02 July.2012 14:30

03.July 2012 16:00

Date and time END

 

02.July 2012 13:25

03.July 2012 15:00

04.July 2012 13:15

Parameter

Weight m

Weight m

Weight m

Weight m

Unit

g

g

g

g

Knudsen-cell 1

3.38686

3.38481

3.38367

3.38268

Knudsen-cell 2

3.32108

3.31935

3.31844

3.31744

Knudsen-cell 3

3.38466

3.38290

3.38183

3.38072

Knudsen-cell 4

3.41452

3.41226

3.41099

3.40991

Measurement Data Experiment 8:

Experiment

8

 

 

 

Nom. Temperature

135°C

 

 

 

Date and time START

 

04.July 2012 14:30

05.July 2012 15:30

06.July 2012 14:10

Date and time END

 

05.July 2012 13:00

06.July 2012 13:10

07.July 2012 07:40

Parameter

Weight m

Weight m

Weight m

Weight m

Unit

g

g

g

g

Knudsen-cell 1

3.38268

3.37995

3.37685

3.37487

Knudsen-cell 2

3.31744

3.31556

3.31274

3.31121

Knudsen-cell 3

3.38072

3.37898

3.37615

3.37459

Knudsen-cell 4

3.40991

3.40680

3.40367

3.40168

At 135 °C, the test item began to change its colour on the surface to a faint orange.

At 150 °C, the upper part of the test item was completely red orange, which is a sign of oxidation. Therefore, the values at 150 °C were not evaluated.

Conclusions:
Under the study conditions, for the test item zinc methacrylate, the following vapour pressures at 20 °C and at 25 °C were calculated from the regression equation: Vapour pressure at 20 °C: 7.84 * 10-06 Pa and at 25°C: 1.22 * 10-05 Pa.
Executive summary:

This study was performed in order to determine the vapour pressure of zinc methacrylate according to the OECD 104 and the EU method A.4. The vapour pressure is one of the physico-chemical properties of a substance and needed for risk assessments. The method is based on the estimation of the mass of test item flowing out per unit of time of a Knudsen cell in the form of vapour, through a micro-orifice under ultra-vacuum conditions. The mass of effused vapour was obtained by determining the loss of mass of the cell. The vapour pressure was calculated by applying the Hertz-Knudsen relation.

The vapour pressure of the test substance zinc methacrylate was determined at nine different temperatures (30, 45, 60, 75, 90, 105, 120, 135 and 150 °C) following EU A.4 using the effusion method (weight loss). Experiments 1 - 5 (nominal temperatures 30, 45, 60, 75, and 90 °C) showed no significant and/or reproducible weight loss. Experiments of Three temperatures ( 105,120,135) could be evaluated as they showed significant and reproducible weight loss. All measured values of the evaluated experiments showed medium reproducibility caused as only minimal weight losses were measured, giving relative standard deviations of less than 40 %. Nevertheless, a straight line with a correlation coefficient of -0.9996 was obtained. Under the study conditions, for the test item zinc methacrylate, the following vapour pressures at 20 °C and at 25 °C were calculated from the regression equation: Vapour pressure at 20 °C: 7.84 * 10-06 Pa and at 25°C: 1.22 * 10-05 Pa (Henke, 2012).

Description of key information

Determination of the vapour pressure according to the OECD Guideline 104 and EU Method A.4 (Henke, 2012).

Key value for chemical safety assessment

Vapour pressure:
0 Pa
at the temperature of:
20 °C

Additional information