Peptones, soybean

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:

2018-04-05

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.:

>= 120 °C

Melting and Boiling Point (DSC)

In the temperature range of 50 – 80 °C, a small endothermic effect was observed. Between 120 – 180 °C an exothermic effect could be detected, with a mean energy of ‑30 J/g.

In the temperature range of 400 – 430 °C a second endothermic effect occurred, directly followed by a second exothermic effect, with a mean energy of -160 J/g.

 

Sample weight / mg	Onset of Effect / °C	Range of effect / °C	Weight loss / mg	Atmospheric pressure / hPa
4.58	51.83 -- 405.67 --	50 – 80 (endo) 120 – 180 (exo) 400 – 430 (endo) 430 – 500 (exo)	3.64	998.4
6.44	46.49 -- 391.75 --	50 – 80 (endo) 120 – 160 (exo) 400 – 430 (endo) 430 – 500 (exo)	3.98	1000.0

 

For a verification of the DSC measurement the capillary method was performed. The test item changed its color from light yellow to yellow at a temperature of 103.8 °C and ascended in the capillary to the top at 124.9 °C. At 141.5 °C the color of the test item changed to brown and at 162.3 °C to black. No melting of the test item could be observed. Combining the results of the DSC measurements and of the capillary method, none of the endothermic effects can be assigned to the melting of the test item. The test item started to decompose at approx. 120 °C.

Conclusions:

The substance decompose at 120 °C before melting.

Executive summary:

A study was conducted according to OECD test guideline 102, Regulation (EC) No 440/2008 method A.1 and EPA OCSPP test guideline 830.7200 to determine the melting point of the test item using differential scanning calorimetry. The test item was weighed out into an aluminium crucible under an inert atmosphere (nitrogen). Two tests with about 5 – 6 mg of the test item were performed. As reference crucible, an empty aluminium crucible was used. The substance is a solid at ambient conditions. In the temperature range of 50 – 80 °C, a small endothermic effect was observed. Between 120 – 180 °C an exothermic effect could be detected, with a mean energy of 30 J/g. For a verification of the DSC measurement the capillary method was performed. The test item changed its colour from light yellow to yellow at a temperature of 103.8 °C and ascended in the capillary to the top at 124.9 °C. At 141.5 °C the color of the test item changed to brown and at 162.3 °C to black. No melting of the test item could be observed. It was concluded that the test item started to decompose at approx. 120 °C.

Description of key information

The substance decompose at 120 °C before melting.

Additional information

The substance as an UVCB consisting of different peptides. Peptides are known to denaturate at non-physiological temperatures, i. e. beyond 60 °C or even less (H. Robert Horton et al.: Biochemie. Pearson Deutschland GmbH, 2008, ISBN 978-3-827-37312-0, S. 144–146). Secondary and tertiary structures are crucial regarding the peptides function and visual appearence. They are mainly configured by non-covalent bonds such as hydrogen bonds or van der waals forces. These bonds become destroyed and/or altered at elevated temperatures. Consequntley, denatured peptides lose their native 3D-structure and with this their functionality.

In order to support the above consideration, a study was conducted according to OECD test guideline 102, Regulation (EC) No 440/2008 method A.1 and EPA OCSPP test guideline 830.7200 to determine the melting point of the test item using differential scanning calorimetry (reference 4.2 -1). The test item was weighed out into an aluminium crucible under an inert atmosphere (nitrogen). Two tests with about 5 – 6 mg of the test item were performed. As reference crucible, an empty aluminium crucible was used. The substance is a solid at ambient conditions. In the temperature range of 50 – 80 °C, a small endothermic effect was observed. Between 120 – 180 °C an exothermic effect could be detected, with a mean energy of 30 J/g. For a verification of the DSC measurement the capillary method was performed. The test item changed its colour from light yellow to yellow at a temperature of 103.8 °C and ascended in the capillary to the top at 124.9 °C. At 141.5 °C the color of the test item changed to brown and at 162.3 °C to black. No melting of the test item could be observed. It was concluded that the test item started to decompose at approx. 120 °C.