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Dissociation constant

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Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2011/04/20-2011/06/01
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Study report in Japanese
Qualifier:
no guideline followed
Principles of method if other than guideline:
No guideline followed but data is required for CSCL-LVE registration
GLP compliance:
no
Specific details on test material used for the study:
- Name of test material (as cited in study report): DMP
- Analytical purity: 99.82 wt %
- Lot/batch No.: 1901/2011

The HPLC method was carried out at various pH values (pH 5.0, 7.0, 9.0, 10.0 and 11.0)

The retention time obtained its maximum value and became stable in equal to and above pH10.

Conclusions:
The retention time obtained its maximum value and became stable in equal to and above pH10.
Endpoint:
dissociation constant
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2013-10-21
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:
yes
Specific details on test material used for the study:
- Name of test material (as cited in study report): Dimethyl Piperazine
- Substance type: Clear liquid
- Physical state: Liquid
- Lot/batch No.: 1903-3/2012
Dissociating properties:
yes
No.:
#1
pKa:
9.78
Temp.:
20 °C
Remarks on result:
other: No details on temperature are provided, however ambient temperature is anticipated
No.:
#2
pKa:
8.31
Temp.:
20 °C
Remarks on result:
other: No details on temperature are provided, however ambient temperature is anticipated

During the preliminary test, inflection points were observed after 2 mL and 34 mL of titrant had been added. The mid-points of 1 mL and 17 mL of titrant addition were investigated for full testing.

Conclusions:
The dissociation constants of the substance were determined to be 9.78 and 8.31 at ambient temperature.

Description of key information

The dissociation constants of the test substance were determined to be 9.78 and 8.31 at ambient temperature following a GLP study conducted in accordance with guideline OECD 112 using the titration method (Younis, 2013) which was assigned as key study.

Key value for chemical safety assessment

Additional information

The pKa values were determined to be 9.78 and 8.31 at 20°C.

The supporting study (K4) showed that the retention time obtained its maximum value and became stable in equal to and above pH10 using the HPLC method.