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EC number: 233-433-0 | CAS number: 10163-15-2
Dissociation constant
Administrative data
Link to relevant study record(s)
- 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
- 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
Reference
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.
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:
pKa of EQP1= 4.705
pKbof EQP1= 9.295
pKa of EQP2= 7.743
pKbof EQP2= 6.257
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