Potassium dihydrogenorthophosphate

Boiling point

Link to relevant study record(s)

Reference

Endpoint:

boiling point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Between 30 September 2009 and 24 October 2009.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

.

Qualifier:

according to guideline

Guideline:

EU Method A.2 (Boiling Temperature)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of GLP inspection: 2009-09-15 Date of Signature on GLP certificate: 2009-11-26

Type of method:

differential scanning calorimetry

Key result

Boiling pt.:

> 723 K

Atm. press.:

101 325 Pa

Results

Thermographic data for Determinations 1 and 2 are shown below.

Thermographic Data – Determination 1

Thermal Event	Interpretation	Temperature
		ºC	K
Endotherm	Loss of volatiles	~200	~473

Thermographic Data – Determination 2

Thermal Event	Interpretation	Temperature
		ºC	K
Endotherm	Loss of volatiles	~200	~473

 The thermograms for determinations 1 to 3 can be seen in Attachment 1

Discussion

Identical thermographic profiles were obtained for the screening 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 as it ensured the absence of ambient moisture which may have been reabsorbed by the sample on cooling.

For the additional test determination, the presence of the endotherm during heating step 1, but its absence during reheating of the sample confirmed that the endothermic event seen in the definitive test was attributable to loss of volatiles of the sample.

Additionally, the change in sample appearance during the tests has been attributed to the test material partially dissolving in the volatile material released on heating, and not due to a phase transition (e.g. melting, boiling) of the test material.

Conclusions:

The test material was determined to have a boiling temperature greater than 723 K. Although the test material was identified as undergoing loss of volatiles from approximately 473 K, this thermal event was not associated with a phase transition (i.e. melting, boiling) of the test material.
This study is considered to satisfy the guideline requirements for this endpoint and is therefore acceptable for use as a key study.

Executive summary:

 Method

The determination was carried out by differential scanning calorimetry (DSC) using the procedure specified in ASTM E537-86, Method A2 Boiling Temperature of Commission Regulation (EC) No 440/2008 of 30 May 2008.

 Conclusion

The test material was determined to have a boiling temperature greater than 723 K. Although the test material was identified as undergoing loss of volatiles from approximately 473 K, this thermal event was not associated with a phase transition (i.e. melting, boiling) of the test material.

Description of key information

One key study (Walker J, 2009) exists. This study is performed in accordance with an acceptable guideline and under the conditions of GLP. 

Additional information

The test material was determined to have a boiling temperature greater than 723 K. Although the test material was identified as undergoing loss of volatiles from approximately 473 K, this thermal event was not associated with a phase transition (i.e. melting, boiling) of the test material.