Disodium hydrogen citrate

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:

from 2017-03-22 to 2017-04-12

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

differential scanning calorimetry

Key result

Atm. press.:

1 013.25 hPa

Decomposition:

yes

Decomp. temp.:

> 158.03 °C

Sublimation:

no

Remarks on result:

other: Beginning of dehydration at 145.42 °C

Preliminary test for melting range

Table 1: Values and Observations from Pre-test melting range

Observations	Temperature
Slightly shrivelled	148 °C
Colour was slightly yellowish and getting darker	from 190 °C
Colour was yellow	220 °C
Colour was light brown	290 °C
Colour was brown, the test item expanded up to the opening of the capillary. The gas burner was turned down. Decomposition was considered	330 °C

Additional test

A colourless condensate was observed. The condensate dropped back and reacted with the still solid test item. The formed liquid turn to yellow and boiled.

DSC measurement

Interpretation and Evaluation of the measurements

Based on the observations of the pre-test and the additional test the first event (endothermic) was indicated as dehydration of the test item with following decomposition. The lowest onset (first event) of the three measurements is stated as start of the dehydration. The end is evaluated with the event marker function and the lowest value of the three measurements is stated as begin of decomposition.

Observations

Table 1: Values and Observations from DSC Measurements

	Mass test item	Mass crucible (before measurement)	Mass crucible (after measurement)	Observations
First Measurement	1.75 mg	46.89 mg	46.20 mg	After the test the crucible was visually unchanged, the crucible was opened and a brown residue was visible.
Second Measurement	1.73 mg	47.63 mg	46.97 mg	After the test the crucible was visually unchanged.
Third Measurement	1.77 mg	47.11 mg	47.49 mg	After the test the crucible was visually unchanged, the crucible was opened the test item was white and glassy solid.

Table 2: Results from DSC measurement

Dehydration	in °C	in K
1st Determination	145.42	418.57
2nd Determination	146.67	419.82
3rd Determination	145.66	418.81
Beginning of event	145.42	418.57
Decomposition	in °C	in K
1st Determination	158.80	431.95
2nd Determination	158.03	431.18
Beginning of event	158.03	431.18

For more information for the evaluation and because the deviation between the first and second determination was above 0.5 °C, a third measurement was performed from 15 °C to 160 °C.

Conclusions:

The substance decomposes before melting above 158.03 °C.

Executive summary:

A study was conducted according to OECD test guideline 102 and Regulation (EC) No 440/2008 method A.1 to determine the melting point of the test item usingdifferential scanning calorimetry(DSC). In the preliminary test, decomposition of the test item was observed. Furthermore, in an additional testcolourless condensate was observed. The condensate dropped back and reacted with the still solid test item. The formed liquid turned to yellow and boiled. The DSC method was performed with three measurements since the deviation between the first and second determination was above 0.5 °C. No melting point could be determined under these circumstances. Based on the observations of the pre-test and the additonal test, the first event (endothermic) was indicated as dehydration of the test item with following decomposition. The lowest onset (first event) of the three measurements was stated as start of the dehydration. The end was evaluated with the event marker function and the lowest value of the three measurements was stated as begin of decomposition. The dehydration temperature was determined to be 145.42 °C and the decomposition temperature 158.03 °C.

As the test item decomposed the validity criteria according to the guideline are not applicable for the determination of the decomposition temperature.

Description of key information

The substance decomposes before melting above 158.03 °C.

Additional information

A study was conducted according to OECD test guideline 102 and Regulation (EC) No 440/2008 method A.1 to determine the melting point of the test item using differential scanning calorimetry (DSC). In the preliminary test, decomposition of the test item was observed. Furthermore, in an additional test colourless condensate was observed. The condensate dropped back and reacted with the still solid test item. The formed liquid turned to yellow and boiled. The DSC method was performed with three measurements since the deviation between the first and second determination was above 0.5 °C. No melting point could be determined under these circumstances. Based on the observations of the pre-test and the additonal test, the first event (endothermic) was indicated as dehydration of the test item with following decomposition. The lowest onset (first event) of the three measurements was stated as start of the dehydration. The end was evaluated with the event marker function and the lowest value of the three measurements was stated as begin of decomposition. The dehydration temperature was determined to be 145.42 °C and the decomposition temperature 158.03 °C.

As the test item decomposed the validity criteria according to the guideline are not applicable for the determination of the decomposition temperature (reference 4.2-1).