Reaction mass of sodium (methylbutyl and pentyl) sulfonate and sodium 1,2-bis(pentyloxycarbonyl)ethanesulphonate

Dissociation constant

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

dissociation constant

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP compliant study according to EU guideline.

Qualifier:

according to guideline

Guideline:

OECD Guideline 112 (Dissociation Constants in Water)

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Dissociating properties:

yes

pKa:

< 3

Remarks on result:

other: Temperature not explicidly provided, but based on the study design it can be assumed that the test was performed at 20°C.

When using citric acid, no inflection point was obtained therefore the Dissociation Constants in Water of the test item cannot be determined by the Titration Method. The pKa is < 3. During the A.6 Water Solubility analysis, UV spectra revealed no absorption maxima therefore the UV method is also not suitable.

Conclusions:

pKa < 3; When using citric acid, no inflection point was obtained therefore the Dissociation Constants in Water of the test item cannot be determined by the Titration Method. The pKa is < 3. During the A.6 Water Solubility analysis, UV spectra revealed no absorption maxima therefore the UV method is also not suitable.

Executive summary:

In the GLP Klimisch 1 study from Younis (2014) the dissociation constant of the registered substance was determined according to test method OECD 112. When using citric acid, no inflection point was obtained therefore the Dissociation Constants in Water of the test item cannot be determined by the Titration Method. The pKa is < 3. During the A.6 Water Solubility analysis, UV spectra revealed no absorption maxima therefore the UV method is also not suitable.

This value will be used for the risk assessment.

Reference 2

Endpoint:

dissociation constant

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

structural similarity

Reason / purpose for cross-reference:

read-across source

Dissociating properties:

no

No.:

#1

pKa:

-0.75

Remarks on result:

other: QSAR ChemAxon

The source substance has the same functional groups when compared to the target substance. Hence, the result is considered relevant for the target substance as well.

Conclusions:

pKa is outside pH 5 to 9.

Executive summary:

The dissociation constant of docusate sodium as calculated with the QSAR ChemAxon is given as -0.75. Based on the same functional groups of the source and target substance the result is considered to be relevant for the target substance as WoE approach.

The pkA can be predicted to be outside the range of 5 - 9 which is given as criterion in R.7.a. Hence, the study is not needed.

Reference 3

Endpoint:

dissociation constant

Type of information:

not specified

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Principles of method if other than guideline:

Assessment of the pKa based on the molecular structure of the registered substance.

GLP compliance:

no

Dissociating properties:

no

Remarks:

The registered substance has no dissociating groups.

The registered substance has no dissociating groups. Hence, a study for the determination of the dissociation constant is not needed.

Conclusions:

The registered substance has no dissociating groups.

Executive summary:

The registered substance has no dissociating groups.Hence, a study for the determination of the dissociation constant is not needed.

Reference 4

Endpoint:

dissociation constant

Type of information:

not specified

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Principles of method if other than guideline:

Assessment of the pKa based on the molecular structure of the registered substance.

GLP compliance:

no

Dissociating properties:

yes

Remarks on result:

other: The registered substance is a salt. Salts are reaction products of acids and bases that retain their ionic character.  So salts are never undissociated. The dissociation constant is only relevant for substances with a acid or basic character.

The dissociation constant study does not need to be conducted as the substance is a salt. Salts are reaction products of acids and bases that retain their ionic character.  So salts are never undissociated. The dissociation constant is only relevant for substances with a acid or basic character.

For salts, the pkA can be predicted to be outside the range of 5 - 9 which is given as criterion in R.7.a. Hence, the study is not needed.

Conclusions:

The dissociation constant is not relevant since the substance is a salt.

Executive summary:

The dissociation constant study does not need to be conducted as the substance is a salt. Salts are reaction products of acids and bases that retain their ionic character.  So salts are never undissociated. The dissociation constant is only relevant for substances with a acid or basic character.

For salts, the pkA can be predicted to be outside the range of 5 - 9 which is given as criterion in R.7.a. Hence, the study is not needed.

Reference 5

Endpoint:

dissociation constant

Type of information:

not specified

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Principles of method if other than guideline:

Assessment of the pKa based on the molecular structure of the registered substance.

GLP compliance:

no

Dissociating properties:

no

Remarks:

The registered substance has no dissociating groups.

The registered substance is a salt. As stated in Guidance R.7a section R.7.1.17.1 "It is important to note that the dissolution of salts from their crystal lattice into individual ions is not intended to be covered by the endpoint dissociation constant. Therefore this section refers only to acid dissociation (pKa)."

Conclusions:

The registered substance is a salt. As stated in Guidance R.7a section R.7.1.17.1 "It is important to note that the dissolution of salts from their crystal lattice into individual ions is not intended to be covered by the endpoint dissociation constant. Therefore this section refers only to acid dissociation (pKa)."

Executive summary:

The registered substance is a salt. As stated in Guidance R.7a section R.7.1.17.1 "It is important to note that the dissolution of salts from their crystal lattice into individual ions is not intended to be covered by the endpoint dissociation constant. Therefore this section refers only to acid dissociation (pKa)."

Description of key information

pKa < 3;  When using citric acid, no inflection point was obtained therefore the Dissociation Constants in Water of the test item cannot be determined by the Titration Method. During the A.6 Water Solubility analysis, UV spectra revealed no absorption maxima therefore the UV method is also not suitable.

Additional information

In the GLP Klimisch 1 study from Younis (2014) the dissociation constant of the registered substance was determined according to test method OECD 112. When using citric acid, no inflection point was obtained therefore the Dissociation Constants in Water of the test item cannot be determined by the Titration Method. The pKa is < 3. During the A.6 Water Solubility analysis, UV spectra revealed no absorption maxima therefore the UV method is also not suitable.

This value will be used for the risk assessment.