Registration Dossier

Diss Factsheets

Administrative data

Endpoint:
dissociation constant
Type of information:
calculation (if not (Q)SAR)
Remarks:
Migrated phrase: estimated by calculation
Adequacy of study:
key study
Study period:
16 Jan 2008 - 14 May 2008
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study has been performed according toOECD guidelines and according to GLP principles.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008
Report date:
2008

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Details on test material:
- Name of test material (as cited in study report): S-500
- Physical state: yellow powder
- Lot/batch No.: MF1456-2345
- Expiration date of the lot/batch: 18 August 2011
- Storage condition of test material: At room temperature in the dark
- Stability under storage conditions: Stable

Results and discussion

Any other information on results incl. tables

It proved not possible to determine the dissociation constants of S-500 experimentally. As an alternative, the pKa values were calculated using the pKalc version 5.0 computer program. Based on the calculation method, it was concluded that component A of the test substance has two basic pKa values, whereas the neutral species of component B has two acidic and two basic pKa values. For the major component A, two pKa values were calculated: 0.36 and 0.96. It was assumed that these pKa values derive from the subsequent protonation of the amide groups. For the neutral species of component B, four pKa values were calculated: -4.48, 0.13, 0.66 and 19.4. It was assumed that these pKa values derive from the subsequent protonation or deprotonation of the amide groups as well as the deprotonation of the sulfonic acid group.

Applicant's summary and conclusion

Conclusions:
It proved not possible to determine the dissociation constants of S-500 experimentally. As an alternative, the pKa values were calculated using the pKalc version 5.0 computer program. Based on the calculation method, it was concluded that component A of the test substance has two basic pKa values, whereas the neutral species of component B has two acidic and two basic pKa values.
For the major component A, two pKa values were calculated: 0.36 and 0.96. It was assumed that these pKa values derive from the subsequent protonation of the amide groups.
For the neutral species of component B, four pKa values were calculated: -4.48, 0.13, 0.66 and 19.4. It was assumed that these pKa values derive from the subsequent protonation or deprotonation of the amide groups as well as the deprotonation of the sulfonic acid group.