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Melting point / freezing point

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melting point/freezing point
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Testing was conducted between 31 March 2010 and 24 August 2010.
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive and done to a valid guideline.
according to guideline
EU Method A.1 (Melting / Freezing Temperature)
equivalent or similar to guideline
EU Method A.1 (Melting / Freezing Temperature)
Version / remarks:
ASTM E537-86
GLP compliance:
Type of method:
differential scanning calorimetry
Key result
Melting / freezing pt.:
>= 723 K
Remarks on result:
other: No atmospheric pressure was recorded for this endpoint.


Please see Attachment 1 for Thermograms and thermographic data for Determinations 1 and 2.

The melting/freezing temperature of HEDP-H has been determined to be not less than 450°C (723K) at 1013 hPa. The result is considered to be reliable.
Executive summary:


General physico-chemical properties of the test item have been determined.

Methods employed are designed to be compatible with those specified in Commission Regulation (EC) No 440/2008 of 30 May 2008, Part A: Methods for the determination of physico-chemical properties.


The determination was carried out by differential scanning calorimetry (DSC) using the procedure specified in ASTM E537-86 designed to be compatible with Method A1 Melting/Freezing Temperature ofCommissionRegulation (EC) No 440/2008 of 30 May 2008.


The melting/freezing temperature of the test item has been determined to be not less than 450°C (723K).

Description of key information

Melting point: The acid form [HEDP-H] was observed to have a melting/freezing temperature of >450°C (>723 K). This conclusion is read across to the salt to indicate that HEDP (2-3Na) will also have a melting temperature of >450 °C (>723 K).

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:
450 °C

Additional information

The melting point of the anhydrous form of the parent acid (HEDP-H) was determined using differential scanning calorimetry (DSC) in accordance with ASTM E537-86 test method and in compliance with GLP. HEDP-H (anhydrous form) was observed to have a melting/freezing temperature of >450°C (>723 K). The DSC thermograms show evidence of loss of water at about 100°C.

This result is read-across to the salt, HEDP (2-3Na); the salt will have a higher melting point than the parent acid. Salts would be expected to melt at a higher temperature than the parent acid, and to decompose on heating.

This conclusion is supported by available data for HEDP-4Na which indicates that the test substance shows no melting up to 500°C at 1013 hPa.