Magnesium bis(dihydrogenorthophosphate)

Melting point / freezing point

Link to relevant study record(s)

Reference

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Testing was conducted between 30 September 2009 and 2 December 2009.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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	77.69	351
Endotherm	Loss of volatiles	107.60	381
Endotherm	Loss of volatiles	259.88	533

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 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. This study is considered to be adequate and reliable for the purpose of registration under REACH (Regulation (EC) No. 1907/2006).

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 of Commission Regulation (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

The melting point of magnesium bis(dihydrogenorthophosphate) was determined according to EU Method A.1 (Melting / Freezing Temperature) and under the conditions of GLP. 

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

450 °C

Additional information

The test material was determined to have a melting temperature greater than 723 K (450°C).