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Administrative data

Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Modern GLP study performed using an acceptable method for the determination of the dissociation constant. However, the test does not completely fulfill the OECD guideline 112. Limited measurements are taken to determine the pKa and no reference substances are employed.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1994

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
Principles of method if other than guideline:
Only two measurements are taken to determine the pKa using the titration method. No reference substances are employed.
GLP compliance:
yes

Test material

Constituent 1
Reference substance name:
PTH-decahydroamide
IUPAC Name:
PTH-decahydroamide
Constituent 2
Reference substance name:
Ro 31-9373/000
IUPAC Name:
Ro 31-9373/000
Details on test material:
The test material received from F. Hoffmann-La Roche Ltd was a white solid powder from lot no. 25927 with a purity of 99.8%.

Results and discussion

Dissociating properties:
not determined
Dissociation constant
No.:
#1
pKa:
8.64
Temp.:
24 °C
Remarks on result:
other: average of two measurements

Any other information on results incl. tables

The average pKa (two measurements) calculated by the Titrator processor was 8.64 ±0.07.

Applicant's summary and conclusion

Conclusions:
The average pKa (two measurements) calculated at 24 °C by the Titrator processor was 8.64 ±0.07.
Executive summary:

An aqueous solution of PTH-Decahydroamide was titrated by a 0.01 N solution of hydrochloric acid using a Mettler titrator, type DL25. The average pKa (two measurements) calculated at 24 °C by the Titrator processor was 8.64 ±0.07.

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