Registration Dossier

Administrative data

Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted to GLP in compliance with agreed protocols with no deviations from standard test guidelines and/or minor methodological deficiences which do not affect the quality of the relevant results

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report Date:
2009

Materials and methods

Test guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
Deviations:
not applicable
Remarks:
Test material impure, main component contained many dissociation constants outside normal practical pH range, two of three dissociation constants within practical pH rage were close enough to overlap, carboxylic acid group extremely variable results
Principles of method if other than guideline:
Estimates were obtained using CD/I-Lab Web Service (ACD/pKa 8.03), computer based estimation software.
GLP compliance:
yes (incl. certificate)
Remarks:
last page of document

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): INK BH11 M
- Substance type: dark red powder
- Lot/batch No.: MB-1A
- Storage condition of test material: room temperature in the dark

Results and discussion

Any other information on results incl. tables

 Dissociation Constant  Result  Functional Group
pKa1   13.47 +/- 0.70  Amide
 pKa 2 9.25*  Ammonium
  pKa3  7.88 +/- 0.20  Secondary amine
  pKa4 4.71 +/- 0.10   Carboxylic acid
  pKa5  -0.75 +/- 0.50  Sulphonic acid
  pKa6  -0.98 +/- 0.18  Sulphonic acid
  pKa7  -1.18 +/- 0.50  Sulphonic acid
  pKa8  -2.05 +/- 0.40  Amide

*  From Albert and Serjeant, Ionisation Constants of Acids and Bases, A Laboratory Manual, 1971 

Applicant's summary and conclusion

Conclusions:
No experimented testing was considered possible using Method 112 of the OECD Guidelines for Testing of Chemicals, 12 May 1981, for the following reasons:
The test material was relatively impure; practical testing is only really possible on pure, single substances.
The main component contained many dissociation constants outside of the normal practical pH range.
Of the three dissociation constants within the practical pH range, two of these were close enough to overlap.
Method development was carried out to attempt to determine the dissociation of the carboxylic acid group; however, the results were extremely variable.

Therefore, estimates were obtained using ACDII-Lab Web Service (ACD/pKa 8.03), computer based estimation software whioch ranged from 13.47 to -2.05 depending on the functional group in question
Executive summary:

No experimented testing was considered possible using Method 112 of the OECD Guidelines for Testing of Chemicals, 12 May 1981, for the following reasons:

The test material was relatively impure; practical testing is only really possible on pure, single substances.

The main component contained many dissociation constants outside of the normal practical pH range.

Of the three dissociation constants within the practical pH range, two of these were close enough to overlap.

Method development was carried out to attempt to determine the dissociation of the carboxylic acid group; however, the results were extremely variable.

Therefore, estimates were obtained using ACDII-Lab Web Service (ACD/pKa 8.03), computer based estimation software whioch ranged from 13.47 to -2.05 depending on the functional group in question