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EC number: 231-509-8 | CAS number: 7601-54-9
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:
- 10 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 Regsitrant / 1733181
- Expiration date of the lot/batch: 01 Nov 2020
- Purity test date: not reported
STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Store in a cool, dry place and well ventilated place
- 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 10 g/L
1.0000 g test substance was weighed into a 100 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.
FORM AS APPLIED IN THE TEST (if different from that of starting material) : solution
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 11.476
- Temp.:
- 20.9
- Remarks on result:
- other: pKa of EQP1
- No.:
- #2
- pKa:
- 8.44
- Temp.:
- 20.9
- Remarks on result:
- other: pKa of EQP2
- Conclusions:
- 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 pKa and pKb values of Prayphos TSP TG are stated:
pKa of EQP1= 11.476
pKb of EQP1= 2.524
pKa of EQP2= 8.440
pKb of EQP2= 5.560
Reference
The calculation results of the pKa/ pKbare presented in the following table.
Table 4. Calculated pKaand pKbvalues of the Main Test EQP1
Determination |
Volume half consumption in mL* |
pKa |
pKb |
Main test 1 |
1.488 |
11.481 |
2.519 |
Main test 2 |
1.499 |
11.463 |
2.537 |
Main test 3 |
1.494 |
11.485 |
2.515 |
Mean |
- |
11.476 |
2.524 |
Standard Deviation |
- |
0.012 |
0.012 |
Table 5. Calculated pKaand pKbvalues of the Main Test EQP2
Determination |
Volume half consumption in mL* |
pKa |
pKb |
Main test 1 |
3.072 |
8.447 |
5.553 |
Main test 2 |
3.086 |
8.438 |
5.562 |
Main test 3 |
3.078 |
8.436 |
5.564 |
Mean |
- |
8.440 |
5.560 |
Standard Deviation |
- |
0.006 |
0.006 |
* In these tables only the extrapolated half consumptions were stated. The calculations are stated in the study 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 in accordance with 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 ofPrayphos TSP TGare stated:
pKa of EQP1= 11.476
pKbof EQP1= 2.524
pKa of EQP2= 8.440
pKbof EQP2= 5.560
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