Registration Dossier

Physical & Chemical properties

Dissociation constant

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
09-05-2012-10-05-2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
- Name of test material (as cited in study report): Jeffcat ZR50
- Physical state: Liquid
- Batch: PFW100207
- Composition of test material, percentage of components: contains 0.03% water
- Storage conditions: in cool, well-ventilated area
Dissociating properties:
yes
No.:
#1
pKa:
9.6
Temp.:
20 °C
Remarks on result:
other: No details on temperature are provided, however ambient temperature is anticipated
No.:
#2
pKa:
8.9
Temp.:
20 °C
Remarks on result:
other: No details on temperature are provided, however ambient temperature is anticipated

Estimation of pKa of Jeffcat ZR50:

The point of inflection of the reaction of Jeffcat ZR50 with the titrant was determined from the ratio of change in pH of the solution to change in volume after each addition of the acid; versus mean volume of the acid applied. From the point of inflection curve, two points at 30 mL and 48 mL were obtained as volumes of the titrant consumed.

The volumes were divided by 2 to obtain the mid-point of the neutralisation points.

The mid-point of the point of the neutralisation points was therefore obtained at the stage of the titration when 15mL and 24 mL of the titrant had been added to the test solution. The pKa of Jeffcat ZR50 was estimated as 9.54 (the pH when 16 mL of titrant had been added to test solution) and 8.88 (i.e. pH at addition of 24 mL of titrant).

In the formal determination, performed comparable to the estimation phase, the pKa of Jeffcat ZR 50 was determined as 9.6± 0.5 and 8.9±0.5.

Conclusions:
The dissociation constants of the substance were determined to be 9.6 and 8.9 at ambient temperature.

Description of key information

The dissociation constants of the test substance were determined to be 9.6 and 8.9 at ambient temperature following a GLP-compliant study conducted in accordance with guideline OECD 112 using the titration method (Younis S, 2012).

Key value for chemical safety assessment

Additional information

pKa1: 9.6 at 20°C

pKa2: 8.9 at 20°C