Disodium L-cystinate

Boiling point

Administrative data

Endpoint:

boiling point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

09 February 2018 - 20 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

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 103 (Boiling Point)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method A.2 (Boiling Temperature)

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7220 (Boiling Point / Boiling Range)

GLP compliance:

no

Type of method:

differential scanning calorimetry

Test material

Test material information

Constituent 1

Reference substance name:

Disodium L-cystinate

EC Number:

265-025-3

EC Name:

Disodium L-cystinate

Cas Number:

64704-23-0

Molecular formula:

C6H10N2Na2O4S2.H2O

IUPAC Name:

disodium (2R)-2-amino-3-{[(2R)-2-amino-2-carboxyethyl]disulfanyl}propanoate

Test material form:

solid: particulate/powder

Results and discussion

Boiling point

Key result

Decomposition:

yes

Decomp. temp.:

> 100 °C

Remarks on result:

other: no boiling temperature

Any other information on results incl. tables

Interpretation: The standard boiling temperature is defined as the temperature at which the vapor pressure of a liquid is the same as the standard pressure (i.e. 1013.25 hPa).

 Preliminary Test: The TGA curve of the test item is shown in Figure 1, see attached. Starting at 125°C, the weight of the sample decreased significantly. At 238°C, the sample weight had decreased by 25%. After the experiment, black residue was observed on the lid of the sample container and a black molten residue remained in the sample container (original color: off-white). The sample container had expanded. The change of the color indicated reaction and/or decomposition of the test item.

Main Study: The DSC curve obtained with Experiment 1 is shown in Figure 2, see attached. An endothermic peak was observed between 25°C and 100°C. Based on the weight loss observed during the preliminary test and the purity of the test item, the endothermic effect was probably due to evaporation of volatile components. The second endothermic peak was observed between 100°C and 175°C. The endothermic effect was probably due to evaporation of water since test item contains water (approximately 6% based on molecular weight). During the preliminary test a weight loss of approximately 6% was also observed from 100°C, indicating the loss of water. Two endothermic peaks were observed between 175°C and 238°C. These effects were due to reaction and/or decomposition of the test item. After the experiment, a dark brown residue remained in the sample container (original color: off-white). The change of the color indicated reaction and/or decomposition of the test item. 

Applicant's summary and conclusion

Conclusions:

Reaction and/or decomposition of the test item was observed during DSC experiment at temperatures of > 100°C (> 373K). Boiling of the test item was not observed below the temperature at which reaction and/or decomposition started. Based on this, the test item has no boiling temperature.

Executive summary:

Reaction and/or decomposition of the test item was observed during DSC experiment at temperatures of > 100°C (> 373K). Boiling of the test item was not observed below the temperature at which reaction and/or decomposition started. Based on this, the test item has no boiling temperature.