Lithium Citrate Tetrahydrate

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:

2016-11-29 to 2016-12-02

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Deviations:

no

GLP compliance:

no

Type of method:

differential scanning calorimetry

Key result

Melting / freezing pt.:

333 °C

Decomposition:

yes

Decomp. temp.:

333 °C

Sublimation:

no

Individual results

Melting point/ melting range: DSC measurement

A first DSC measurement in aluminium crucibles with a hole showed a multistage endothermal effect in the temperature range of 90 - 180 °C. A second endothermal effect was observed in the temperature range of 290 - 340 °C. This endothermal effect was directly followed by an exothermal effect in the temperature range 340 - 380 °C. The onset temperature (see table 1) was derived from the intersection of the tangent line with the highest slope of the endothermal peak with the baseline.

A second DSC measurement in aluminium crucibles with a hole showed an endothermal effect in the temperature range of 60 - 180 °C. This measurement was terminated at 250 °C. The mass loss was 25 %. This mass loss corresponds with the water content of the test item.

The results of the DSC measurements are summarized in table 1.

Table 1: Melting point (DSC measurements)

Ident no.	Test item/ mg	Starting temperature/  °C	Final test temperature/°C	Temperature range/ °C	Onset (melting)/ °C	Crucible	Observations after the measurement
35935	9.66	25	500	90 – 170 290 – 340	- 333.28	Aluminium with a hole	Black residue, mass loss: 52 %
35937	13.27	25	250	60 - 180	-	Aluminium with a hole	Test item was baked, mass loss: 25 %

An additional measurement with the capillary method was performed in order to clarify the melting range.

Melting point / melting range: capillary tube in a metal block

A measurement with the capillary method was performed to clarify the results of the DSC measurements. Since this measurement was performed only as a verifying screening a high heating rate of 10 K/min was chosen and therefore the absolute temperature values derived with the capillary method are not as accurate as the DSC results. The filling height of the test item was approximately 5 mm.

The results are summarized in table 2.

Table 2: Results of the capillary method

No.	Set point/ °C	Heating rate/ K/min	End point/ °C	Remarks
1	250	10	400	Start at 250 °C: Evaporation of water Approx. 320 °C: Test item started to melt Approx. 345 °C: Test item showed discolouring Approx. 365 °C: Test item showed discolouring to brown and was not completely melted Approx. 365 – 400 °C: no further change (test item not fully melted)

Under consideration of the results from the DSC measurements and the capillary method it was concluded that the test item melted under decomposition starting at 333 °C.

Conclusions:

The test item, lithium citrate tetrahydrate, melted under decomposition starting at 333 °C.

Description of key information

The test item, lithium citrate tetrahydrate, melted under decomposition starting at 333 °C.

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

333 °C

Additional information

The melting point range was determined by differential scanning calorimetry (DSC) according to EU method A.1 and OECD guideline 102 (Albemarle, 20160428.01, 2017). The test item, lithium citrate tetrahydrate, melted under decomposition starting at 333 °C.