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Administrative data

Endpoint:
melting point/freezing point
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Experimental Starting Date: 20 July 2012; Experimental Completion Date: 23 January 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not effect the quality of the relevant results.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
EU Method A.1 (Melting / Freezing Temperature)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 102 (Melting point / Melting Range)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 830.7200 (Melting Point / Melting Range)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
other: differential scanning calorimetry

Test material

Constituent 1
Test material form:
other: solid

Results and discussion

Melting / freezing point
Melting / freezing pt.:
132 °C
Decomposition:
yes
Decomp. temp.:
ca. 132 °C
Remarks on result:
other: The test item melted, with decomposition, from approximately 132 °C (405 K)

Any other information on results incl. tables

Results

Thermograms and thermographic data for determinations 1 and 2 are shown in Figure 3.1 and Figure 3.2 (attached background material), and in the following tables.

 

Table 3.2        Thermographic Data – Determination 1

 

Thermal Event

Interpretation

Temperature

ºC

K

Approximate endotherm onset temperature.

Approximate onset of melting with decomposition.

131.70

405

Table 3.3        Thermographic Data – Determination2

 

Thermal Event

Interpretation

Temperature

ºC

K

Approximate endotherm onset temperature.

Approximate onset of melting with decomposition.

136.24

409

Overall result: The test item melted, with decomposition, from approximately 132 °C (405 K)

Discussion:

Assignment of the thermographic data was performed with the assistance of observations recorded during a simplified liquid bath apparatus assessment of the test item. The test item was initially observed to be a beige paste-like consistency at the start of the assessment and then was observed to melt over a very broad range of approximately 100 to 160°C, discolouring with melting. Once liquefied, the test item continued to discolour as heating continued.

It can therefore be concluded that the test item decomposed during melting. Due to the initial low rate of enthalpy change during the melting/decomposition process, the onset temperature could only be approximated. Differences between the approximate onset temperatures observed by DSC and visual techniques may be attributable to the extremely subjective nature of the visual assessment for a substance of this physical state and/or the influence of heating rate on the decomposition process. However as the DSC heating rate is automated and repeatable, and quantification is taken from a defined thermal event, this has been taken as the definitive test result.

Typically a heating rate of 1 °C/minute would be used for definitive quantification of a melting temperature. However in this case, no definitive melting temperature was identified. The elevated heating rate of 20 °C/minute used in the reported determinations was considered optimal in this case as it aided integration of the onset reported (the low rate of enthalpy change observed would be further reduced with a decreased heating rate) and also, it minimized the influence of decomposition on the experimental results. At a reduced heating rate, the test item would be exposed to an elevated temperature for a longer time period which could potentially decrease the onset temperature of any thermal decomposition.

Applicant's summary and conclusion

Conclusions:
The test item melted, with decomposition, from approximately 132 °C (405 K).
Executive summary:

Method

The determination was carried out using a differential scanning calorimetry procedure designed to be compatible with Method A1 Melting/Freezing Temperature of Commission Regulation (EC) No 440/2008 of 30 May 2008, Method 102 of the OECD Guidelines for Testing of Chemicals, 27 July 1995, and Method 830.7200 of the OPPTS Guidelines, March 1998.

Result

The test item melted, with decomposition, from approximately 132 °C (405 K).