Dipotassium hydrogenorthophosphate

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 05 November 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)

Type of method:

other: Differential scanning calorimetry (DSC)

Melting / freezing pt.:

> 723 K

Decomposition:

no

Sublimation:

no

Remarks on result:

other: Atm pressure not reported

Thermographic data for Determinations 1 and 2 are shown in the following tables respectively:

Thermographic Data – Determination 1

Thermal Event	Interpretation	Temperature
		ºC	K
Endotherms	Start of loss of volatiles End of loss of volatiles	~48.81 ~147.22	~322 ~420
Endotherm	Semi-reversible, possible crystal form transition	308.53	582

Thermographic Data – Determination 2

Thermal Event	Interpretation	Temperature
		ºC	K
Endotherms	Start of loss of volatiles End of loss of volatiles	~48.19 ~148.81	~321 ~422
Endotherm	Semi-reversible, possible crystal form transition	308.39	582

The thermographic data is shown in attachment - Thermograms

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 from approximately 321 K to approximately 422 K and a semi-reversible, possible crystal form transition at 582 K, none of these thermal events were associated with a phase transition (i.e. melting) of the test material.

This study is conducted according to an appropriate guideline and under the conditions of GLP and therefore the study is considered to be acceptable and to adequately satisfy both the guideline requirement and the regulatory requirement as a key study for this endpoint.

Executive summary:

The test material was determined to have a melting temperature greater than 723 K, by differential scanning caloritry, using ASTM E537-86, Method A1 Melting/Freezing Temperature of Commission Regulation (EC) No 440/2008 of 30 May 2008. Although the test material was identified as undergoing loss of volatiles from approximately 321 K to approximately 422 K and a semi-reversible, possible crystal form transition at 582 K, none of these thermal events were associated with a phase transition (i.e. melting) of the test material.

Description of key information

One key study exists. This study (Walker J, 2010) was conclusive, done to a valid guideline (EU Method A.1) and the study was conducted under GLP conditions. It is therefore scientifically justified for use as a key study under Regulation (EC) No. 1907/2006.

Additional information

The test material was determined to have a melting temperature greater than 723 K (450°C). Although the test material was identified as undergoing loss of volatiles from approximately 321 K to approximately 422 K and a semi-reversible, possible crystal form transition at 582 K, none of these thermal events were associated with a phase transition (i.e. melting) of the test material.