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Dissociation constant

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Reference
Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
Batch number: 23ADB/50
Manufacturing date: November 22nd, 2018
Expiry date: November 21st, 2023
Name: Trisodium (2S)-2,6-bis (3- carboxylatopropanamido) hexanoate_Disuccinyl lysine sodium salt
Appearance: Liquid
Colour: Brown
Odour: Characteristic
Container: n/a
Dissociating properties:
no
Remarks on result:
not determinable
Remarks:
A definitive equivalence point could not be determined, but there was evidence of an acidic pKa over the pH range of approximately 3 to 6.

Temperature during the preliminary tests ranged from 19.3 to 20.1°C.

The preliminary test indicated there was no difference between the curves generated from titration of water with the base titrant compared to the titration of the test substance solution (aq) with the base titrant, which means the test substance does not have a dissociation constant in basic conditions. The titration of the test substance with acid titrant did indicate a difference. A definitive equivalence point could not be determined, but there was evidence of an acidic pKa over the pH range of approximately 3 to 6.

Conclusions:
The test substance, disuccinyl lysine sodium salt, showed evidence of an acidic pKa over the pH range of approximately 3-6.
Executive summary:

An experimental test has been conducted to determine the pKa of the test substance, disuccinyl lysine sodium salt, by potentiometric titration (according to test method OECD 112). A definitive equivalence point could not be determined, but there was evidence of an acidic pKa over the pH range of approximately 3-6.

Description of key information

The test substance, disuccinyl lysine sodium salt, showed evidence of an acidic pKa over the pH range of approximately 3-6.

Key value for chemical safety assessment

Additional information

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