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Boiling point

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Reference
Endpoint:
boiling point
Type of information:
experimental study
Adequacy of study:
key study
Study period:
May 22 to June 27, 2014
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Justification for type of information:
The study was conducted according to an internationally recognised method, and under GLP.
Restrictions apply considering the difficulty to interprete the result obtained for such complex substance and to determine the initial boiling point & temperature of decomposition of the substance. The substance is considered to be adequately characterised. Therefore a validation with restrictions applies.
Qualifier:
according to
Guideline:
OECD Guideline 103 (Boiling point/boiling range)
Version / remarks:
dated 27. Jul. 1995
Deviations:
yes
Remarks:
A Cottrell vessel with three openings and an additional thermometer in the sample was used instead of a vessel with two openings. It allows to detect the temperature of the substance in the Cottrell vessel.
Qualifier:
according to
Guideline:
EU Method A.2 (Boiling Temperature)
Version / remarks:
Regulation (EC) n°761/2009, dated 23. Jul.2009
Deviations:
yes
Remarks:
A Cottrell vessel with three openings and an additional thermometer in the sample was used instead of a vessel with two openings. It allows to detect the temperature of the substance in the Cottrell vessel.
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. certificate)
Remarks:
inspected on 29 and 30 November 2010 / signed on 11 April 2011
Type of method:
dynamic method
Key result
Decomposition:
ambiguous
Remarks on result:
other: No defined boiling point of the test item could be determined using this method.

Two experiments were performed using the dynamic method and the following observations were made:

At a sample temperature of approxametly 125 °C, boiling and formation of a colourless condensate were observed.

However, the Cottrell pump didn’t pump at this temperature. This might be due to higher volatile components of the test item or to decomposition of the substance.

Then, boiling, indicated by pumping of the Cottrell pump, was observed at 247.8 °C (first determination, at 99514 Pa) and 251.7 °C (second determination, at 99792 Pa), while the temperature measured in the sample fluctuated between 338 and 370 °C.

The observed fluctuated temperatures measured in the sample might be caused through dropping back of the condensate which cooled down the test vessel.

The thermometer in the Cottrell pump showed a much lower temperature than the temperature in the sample. If a liquid boils, the measured temperatures of the thermometers should be similar. Therefore, the temperature difference between the thermometers is considered as a sign of decomposition.

After cooling down, the test item appeared visually unchanged, but the odour had changed to burned sugar. This change of odour indicated also decomposition of the test item during the experiment.

Finally no initial boiling point of the test item could be determined using the dynamic method and initial temperature of decomposition of the test item is not clearly determined.

No observations were made which might cause doubts on the validity of the study outcome.Therefore, the result of the study is considered valid.

Conclusions:
No clear initial boiling point of the test item could be determined using the dynamic method. In addition, signs of decomposition were observed when the substance is heated up to 370°C.
Executive summary:

A study was conduted to determine the initial boiling point of the test substance under GLP according to EU Method A.2 and OECD 103 following the dynamic method.

Two experiments were conducted but no clear initial boiling point of the test item could be determined using this method and considering the complex nature of the substance. In addition, signs of decomposition were observed when the substance is heated up to 370°C : a colourless condensate observed at a sample temperature of approximately 125°C might be due to the higher volatile components of the test item (minor part of the substance) or to the decomposition of the substance. In addition, a significant difference was observed between the sample temperature and the temperature of the Cottrell pump when a boiling is detected and the odour changed to burned sugar after cooling down of the sample. 

Description of key information

No clear initial boiling point of the test item could be determined using the dynamic method.

In addition, signs of decomposition were observed when the substance is heated up to 370°C.

Key value for chemical safety assessment

Additional information

A reliable experimental study, conducted according to a recognized OECD/EC, following the dynamic method and under GLP, is available. It is considered as a key study. However, no clear initial boiling point or initial decomposition temperature could be determined using the dynamic method. Considering the complex nature of the substance, no key value is retained for this endpoint.