L-Arginine, N2-(2,3-dihydroxypropyl)-, monohydrochloride

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:

18 March 2020 to 14 July 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method A.1 (Melting / Freezing Temperature)

Version / remarks:

2008

Deviations:

yes

Remarks:

The pour point method was modified due to the viscosity of the test item

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Version / remarks:

1995

Deviations:

yes

Remarks:

The pour point method was modified due to the viscosity of the test item

Principles of method if other than guideline:

The pour point method was modified due to the viscosity of the test item. It would have required too high a temperature to transfer it to a typical pour point vessel without the test item solidifying during the transfer and sticking to the sides of the vessel. Previous transfer attempts of the test item had come across this issue including trapped air pockets/bubbles. Also, heating too high may have affected the result as the test item was expected to decompose >130°C. Therefore, it was decided to perform the test in the clear glass container it was supplied in and heat it up in increments of 3 °C from 46 °C (the starting temperature specified in the test guidelines).

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of Inspection: 21 August 2018; Date of Issue: 19 November 2018

Type of method:

differential scanning calorimetry

Remarks:

A modified pour point method was followed in addition to the DSC method

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature, in the dark

Melting / freezing pt.:

58 °C

Remarks on result:

other: pour point

Key result

Melting / freezing pt.:

>= 32.8 - <= 86.6 °C

Table 2 Thermographic Data

Thermal Event	Interpretation	Temperature (°C)
		Determination 1	Determination 2
Endotherm	Onset of softening event	32.83	32.87
	Endset of softening event	84.37	86.62

Atmospheric pressure: 100 kPa

After heating to 100°C, the samples had lost ≤ 2% of their original weight

Melting temperature: over the range 32.8 to 86.6°C (306 to 360 K)

 

Pour Point Method

The results of the main test are shown in the following table:

Table 3 

Observation	Determination 1	Determination 2
Stationary point (°C)	55	55
Pour point (°C)	58	58

Overall pour point result: 58 ± 3°C (331 ± 3 K)

Conclusions:

The melting point of the test item has been determined by differential scanning calorimetry to be over the range of 32.8 to 86.6 °C (306 to 360 K).
Additionally, the melting point of the test item has been determined by a modified pour point method to be 58 ± 3 °C (331 ± 3 K).

Executive summary:

As the substance was a extremely immobile viscous liquid at room temperature, the melting point was investigated in accordance 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, using both differential scanning calorimetry and a modified pour point method.

From the DSC, a shallow endotherm attributed to test item softening was observed over the range of 32.8 to 86.6°C (306 to 360 K). The pour point was determined to be 58 ± 3°C (331 ± 3K), which confirmed that the shallow endotherm was indicative of the temperature range in which the test item becomes more mobile. 

Description of key information

Melting range 32.8 to 86.6°C; OECD 102; Fox, J. M. (2020)

Additional information

No key value for chemical safety assessment is reported as no single value was identified for melting point and instead a melting range and a pour point value was determined.