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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:
19 Oct 2012 to 26 Oct 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
no
GLP compliance:
yes
Type of method:
gas saturation method
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Name of test item (as cited in study report): Butyl Zimate
- Chemical name: zinc bis (dibutyldithiocarbamate)
- Batch no.: 2010472517
- Purity: 98%

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
A single preparation of the test substance was prepared by weighing approximately 0.02 g of the test substance accurately into a 100 mL volumetric flask. Approximately 60 mL of dichloromethane was added to the flask and the flask was shaken to dissolve. The flaks was filled to the mark when the solution had equilibrated to room temperature and left overnight to ensure dissolution. The stock solution was called Standard 1.
The actual weight of Standard 1 was 0.0230 g. Stock 1 Solution was diluted by pipetting 1.0 mL into a 25 mL volumetric flask and making up to the mark with dichloromethane. This solution was named Standard 1A. (9.2 mg/L). When the absorbance at 264.23 nm was calculated using the linearity graph previously prepared during verification of the test method, the value corresponded to a concentration of 8.26 ppm. i.e. recovery of standard is 89.8%, which is deemed acceptable for the analysis being undertaken. The collected test solutions were analysed without further dilution.
Key result
Temp.:
25 °C
Vapour pressure:
< 0 Pa

RESULTS:

- 25 °C temperature data: The maximum temperature was 25.2°C, the minimum temperature was 24.6°C and the mean temperature was 24.9°C. All data points were within the ± 0.5°C criteria used for this test, the results obtained are deemed acceptable and will be quoted as ± 0.5°C.

- Actual weight Standard 1: 0.0230 g

- Calculated Theoretical calculation Vapour pressure: No analyte was observed in the test solutions. The vapour pressure at 25°C ± 0.5°C was determined to be< 1 x 10-4Pa based onthetheoretical calculation detailed below assuming that theconcentrationin each test solution was lower than the LOO of 0.17 mg/L.Where:

Theoretical Amount in solution = 0.17 mg/Lx 100 mL (dilution)/1000000 (conversion to g).

Total Time of Gas Flow (mins) = duration of test from start to finish.

Average Gas Flow (seconds/100 mL) = Time taken for gas flow to travel 100 mL.

Gas Flow (L) = Flow that travels through the system in one minute converted from mL to litres.

Total Gas Flow (m3-volume of saturated gas) = Gas flow (L) in one minute x total time of gas flow/ 1000 to convert to m3 for use in calculation below:

Vapour Pressure is calculated as:(W/V) * (RT / M), where:

W = mass of evaporated test substance (g)

V = volume of saturated gas (m3)

R = universal gas constant (8.314 J/mol/K)

T = temperature (K)

M = molar mass of test substance (g/mol)

OBSERVATIONS

The direct measurement of vapour pressure using the Gas Saturation method of determination has not been possible. The test substance was analysed in triplicate and no analyte was detected in any of the test solutions.

An estimated value has been determined based on the LOD of the quantitative UV method. Since no analyte was determined by UV analysis, the sample has a vapour pressure lower than 1E-04 Pa at 25 °C. No experimental evaluation of vapour pressure at 20 °C using this method has been performed as results would not be significantly different and would not lower than those obtained at 25 °C. A value of < 1E-04 Pa at 20 °C will be reported as inferred.

The estimate analyte concentration quoted, based on the analysis conditions, assumed the following:

- Gas saturation was achieved

For gas saturation to be achieved, the extreme gas flow rates have to be > 30 % different (which they were for this analysis, 49.8 % difference in extreme gas flow rate) and the calculated vapour pressure be < 30 % different. As no actual analyte concentration is determined, it is not possible to assess repeatability of the calculated vapour pressure accurately.

- The analyte is stable in dichloromethane during the analysis.

There is no indication of instability in the testing performed. The results do not prove, definitively, that gas saturatuon had occurred (as no analyte was detected and as a consequence all subsequent calculations were carried out using a "less than LOD" value) and therefore it has been assumed.

Description of key information

The vapour pressure of the test substance was determined to be < 1E-04 Pa at 25 °C (± 0.5 °C).

Key value for chemical safety assessment

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

Additional information

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