Registration Dossier

Diss Factsheets

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:
16 - 17 October 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 112 (Dissociation Constants in Water)
Deviations:
no
GLP compliance:
no
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Lead Registrant / 8-40099-56
- Expiration date of the lot/batch: 01 Jan 2019
- Purity test date:
- Purity: 95.7%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Store in a cool, dry place; protect from moisture
- Solubility and stability of the test substance in the solvent/vehicle: soluble

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Final preparation of a solid: Test substance Solution 20 g/L (for titration with HCl)
4.0000 g test substance was weighed into a 200 mL volumetric flask, deionised water was added and solved in the ultrasonic bath. After complete solution the volumetric flask was filled up to the mark with deionised water. No Tyndall effect (with a laser beam was not scattered when transmitted through the liquid) could be observed indicating that no colloidal dispersed particles were present.
Test substance Solution 10 g/L (for titration with NaOH)
1.0000 g test substance was weighed in a 100 mL volumetric flask, filled half with deionised water and then the volumetric flask was set into the ultrasonic bath. After complete solvation the volumetric flask was filled to the mark and no Tyndall effect (with a laser beam was not scattered when transmitted through the liquid) could be observed indicating that no colloidal dispersed particles were present.

FORM AS APPLIED IN THE TEST (if different from that of starting material) : solution

Dissociating properties:
yes
No.:
#1
pKa:
4.696
Temp.:
20.5 °C
Remarks on result:
other: with HCl
No.:
#2
pKa:
4.7
Temp.:
20.5 °C
Remarks on result:
other: with HCl
No.:
#3
pKa:
4.72
Temp.:
20.5 °C
Remarks on result:
other: with HCl
No.:
#1
pKa:
7.738
Temp.:
20.5 °C
Remarks on result:
other: with NaOH
No.:
#2
pKa:
7.751
Temp.:
20.5 °C
Remarks on result:
other: with NaOH
No.:
#3
pKa:
7.74
Temp.:
20.5 °C
Remarks on result:
other: with NaOH

Table 5. Calculated pKa and pKb values with HCl (EQP1)

Determination

Volume half consumption in mL*

pKa

pKb

Main test 1

1.488

4.696

9.304

Main test 2

1.499

4.700

9.300

Main test 3

1.494

4.720

9.280

Mean

-

4.705

9.295

Standard Deviation

-

0.013

0.013

Table 6. Calculated pKa and pKb values with NaOH (EQP2)

Determination

Volume half consumption in mL*

pKa

pKb

Main test 1

0.062

7.738

6.262

Main test 2

0.067

7.751

6.249

Main test 3

0.089

7.740

6.260

Mean

-

7.743

6.257

Standard Deviation

-

0.007

0.007

* In these tables only the extrapolated half consumptions were stated. The calculations are stated in the test report.

Note: All calculations are performed with unrounded values. Therefore, recalculation with rounded values may lead to slightly different results.


Conclusions:
The standard deviation of three independent performances of the determination of the dissociation con-stant was within ± 0.1 log units. The validity criterion was met.
The three evaluated main determinations showed good correlation.
The calculated pKa and pKb values of Phoskadent Na 211 are stated:
pKa of EQP1= 4.705
pKb of EQP1= 9.295

pKa of EQP2= 7.743
pKb of EQP2= 6.257

Description of key information

Study performed according to OECD 112.

Key value for chemical safety assessment

Additional information

The standard deviation of three independent performances of the determination of the dissociation constant was within ± 0.1 log units. The validity criterion was met.

The three evaluated main determinations showed good correlation.

The calculated pKaand pKbvalues of Phoskadent Na 211 are stated:

pKof EQP1= 4.705

pKbof EQP1= 9.295

 

pKof EQP2= 7.743

pKbof EQP2= 6.257