Trimagnesium bis(orthophosphate)

Melting point / freezing point

Link to relevant study record(s)

Reference

Endpoint:

melting point/freezing point

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

Testing was conducted between 30 September 2009 and 30 October 2009.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study conducted in compliance with agreed protocols, with no deviations from standard test guidelines (EU Method A.1). The substance tested is a hydrated form of the substance to be registered and therefore in accordance with 'Data Submission Manual, Part 18 - How to report substance identity in IUCLID 5 for registration under REACH' the hydrated form is considered to be different to the anhydrous form. Read-across from trimagnesium phosphate-4-hydrate to the anhydrous trimagnesium bis(orthophosphate) is justified on the basis that the addition of water is unlikely to detrimentally affect the physicochemical or (eco)toxicological profile of the substance. The reliability has been amended in accordance with 'practical guide 6: How to report read-across and categories' which states that the maximum reliability for a read-across study is 2. The study is considered to be adequate and reliable for the purpose of registration under REACH (Regulation (EC) No. 1907/2006).

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of GLP inspection: 15 September 2009 Date of Signature on GLP certificate: 26 November 2009

Type of method:

thermal analysis

Remarks:

Differential scanning calorimetry (DSC)

Melting / freezing pt.:

> 723 K

Remarks on result:

other: .

Results

Definitive test

Thermal analysis data for Determinations 1 and 2 are shown in the following tables, respectively.

Table 3     Thermographic Data – Determination 1

Thermal Event	Interpretation	Temperature
		ºC	K
Endotherm	Loss of volatiles	185.35	459

 

Table 4      Thermographic Data – Determination 2

Thermal Event	Interpretation	Temperature
		ºC	K
Endotherm	Loss of volatiles	184.44	458

Thermograms are presented as an attachment.

Discussion

Identical thermographic profiles were obtained for the definitive test under both air and nitrogen atmospheres. However, as possible loss of volatiles was to be investigated by a cyclic heating program, nitrogen was used as the furnace atmosphere for the additional test determination as it would ensure the absence of ambient moisture which could have been reabsorbed by the sample on cooling.

For the additional test determination, the presence of the first endotherm during heating step 1, but its absence during reheating of the sample confirmed that this endothermic event was attributable to loss of volatiles. Additionally, the unchanged residue appearance confirmed that the thermal event did not originate from a phase transition (e.g. melting) of the test material.

Conclusions:

The test material was determined to have a melting temperature greater than 450°C. Although the test material was identified as undergoing loss of volatiles at approximately 458 K, this thermal event was not associated with a phase transition (i.e. melting) of the test material.

Executive summary:

Method

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

Conclusion

The test material was determined to have a melting temperature greater than 723 K. Although the test material was identified as undergoing loss of volatiles at approximately 458 K, this thermal event was not associated with a phase transition (i.e. melting) of the test material.

Description of key information

Melting point: > 450 °C (EU Method A.1, OECD 102, GLP) 

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

450 °C

Additional information

The melting/freezing temperature of trimagnesium bis(orthophosphate) was determined by differential scanning calorimetry (DSC) in a study conducted according to EU Method A.1 and GLP. The melting point of the test material was determined to be greater than 450 °C.