β,β-carotene

Melting point / freezing point

Administrative data

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Experimental starting date: 12 January 2018 Experimental completion date: 08 March 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

GLP compliance:

yes (incl. QA statement)

Type of method:

differential scanning calorimetry

Test material

Test material information

Constituent 1

Reference substance name:

β,β-carotene

EC Number:

230-636-6

EC Name:

β,β-carotene

Cas Number:

7235-40-7

Molecular formula:

C40H56

IUPAC Name:

β,β-carotene

Details on test material:

Identification: Beta-Carotene
Appearance/Physical state: brown-red crystalline powder
Lot No: WC01607211
Purity: 100.4% by UV Assay (USP 851)
97.4% by LC Method (USP 621)
Expiry date: 19 July 2018
Storage conditions: Approx. 4 °C, in the dark, under nitrogen

Results and discussion

Melting / freezing point

Melting / freezing pt.:

174 °C

Decomposition:

yes

Decomp. temp.:

240 °C

Any other information on results incl. tables

ThermographicData

 

ThermalEvent	Interpretation	Temperature (°C)
		Det 1	Det 2	Det 3	Det 4	Det 5	Det 6
Endotherm	Onset of melting	164.77	163.51	166.76	167.83	163.06	162.02
	Extrapolated onset of melting	180.97	180.90	173.88	174.02	181.50	181.36
n/a	Loss in mass of original weight	62%	60%	2%	2%	65%	64%

After heating, Determinations 7 to 9 had lost approximately 5%, 0% and 59% of their original weight respectively.

 

Mean melting temperature (Determinations 3and 4):           174 ± 0.5 °C (447 ± 0.5K)

 

 Discussion

The main endothermic event was considered to be related to the test item melting. This occurred at 174°C when the heating rate was 5 °C/min but at a slightly higher temperature of 181 °C when the heating rate was at a higher rate of 20 °C/min.

 

To investigate whether this was a definitive melting point for the test item, Determination 7 incorporated the test item being heated so that it melted, cooled to solidify and then heated again. However, when heated for a second time there was no repeat of the phase change. On the chance that the test item had not solidified on cooling, a second procedure was performed that left the sample over night at ambient temperature to give enough time to solidify. The following day the sample was reheated. This second procedure is shown in Determinations 8 and 9. Again, no melting endotherm was observed on re-heating.

The above investigative work indicated, even though the test item melted, that the test item must have undergone decomposition or reaction before or during the melting phase. As only a small amount of the original sample weights were lost up to 190 °C and 220 °C, it suggests signification decomposition had not occurred. In contrast, following the melting phase the test item underwent decomposition which accounted for approx. 60% loss in weight. This was evident in the thermograms by an exotherm event which started from approx. 240 °C.

 

Additionally, there is a small exothermic event in Determinations 1, 2, and 5 to 8 that starts from approx. 50 °C.

Similar thermographic profiles were obtained using air and nitrogen atmospheres. This suggested that the decomposition was probably thermal and not oxidative.

Applicant's summary and conclusion

Conclusions:

The test item has been determined to melt at 174 ± 0.5 °C (447 ± 0.5 K). However, decomposition or a reaction occurred prior to and/or during the melting. Significant decomposition occurred from approx. 240 °C (513 K).

Executive summary:

Melting/Freezing Point.174 ± 0.5 °C (447 ± 0.5 K), by differential scanning calorimetry, designed to be compatible with Method A.1 Melting/Freezing Temperature of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 102 of the OECD Guidelines for Testing of Chemicals, 27 July 1995. However, decomposition or a reaction occurred prior to and/or during the melting. Significant decomposition occurred from approx. 240 °C (513 K).