Registration Dossier

Administrative data

Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
other information
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2004
Report Date:
2004

Materials and methods

Principles of method if other than guideline:
An aqueous solution of the test substance is titrated with acid or base producing a titration curve of pH versus volume of acid or base added.
The inflection point(s) on the curve are used to determine the dissociation constant(s) of the test substance.
The analysis was carried out using a solution of the test substance in water containing a small amount of methanol.
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent

Results and discussion

Dissosciation constant
pKa:
8.17
Temp.:
23 °C

Any other information on results incl. tables

Calculation of Individual Results
The pKa is given by the pH value corresponding to half the volume of titre required to attain the equivalence point.
The auto titrator calculated the titre during the course of each analysis and the pKa was therefore assessed using the
four data points around the half volume value calculated.
For each test and individual dissociation constant, the values given below were used to construct a linear regression curve, from which the intercept and gradient values were used to calculate the pKa for each half volume.

Test 1: pKa =8.179 Test 1: pKa =8.163 Test 3: pKa= 8.162

Calculation of Ideal pKa value
To calculate the ideal pKa values, a plot of individual pKa results versus sample weight for each test is used to
determine the ideal pKa value by extrapolation back to zero weight.

Applicant's summary and conclusion