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EC number: 204-625-1 | CAS number: 123-41-1
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
pH
Administrative data
- Endpoint:
- pH
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2013-03-11
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: well-documented study, data were gained within the water solubility determination of the test item according the preliminary test from the OECD 105 guideline
Cross-referenceopen allclose all
- Reason / purpose for cross-reference:
- reference to same study
Reference
- Endpoint:
- melting point/freezing point
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2013-03-06 to 2013-03-07
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Well documented guideline study in accordance with OECD 102
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 102 (Melting point / Melting Range)
- Deviations:
- no
- GLP compliance:
- yes
- Type of method:
- method to determine freezing temperature
- Melting / freezing pt.:
- < -20 °C
- Atm. press.:
- ca. 100 kPa
- Remarks on result:
- other: The test substance was not frozen, after overnight storage at -20 °C.
- Conclusions:
- The freezing point of a 45 % solution of choline hydroxide was determined in an OECD 102 guideline study and consideration of guidance given in ECHA Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7a: Endpoint Specific Guidance December 2016 Section R.7.1.2.1., classified as reliable without restrictions. On removal from the freezer, a visual assessment of the physical state of the test substance was performed and an observation that the test substance was not frozen was recorded. A full study does not need to be conducted below a lower limit of -20 °C. Hence the freezing point of the test item was determined to be < -20 °C in this study. The outcome of this study is considered reasonable and within the scientifically expected ranges.
- Executive summary:
The freezing point of a 45 % aqueous solution of choline hydroxide was determined according to OECD Guideline 102 (Melting point / Melting Range). The freezing point of the test item was determined to be < -20 °C in this study.The study was classified as Klimisch 1 (reliable without restriction) and fully satisfies the requirements of OECD 102.
- Reason / purpose for cross-reference:
- reference to same study
Reference
- Endpoint:
- relative density
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2013-03-18
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Well documented guideline study (OECD 109) without restrictions.
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 109 (Density of Liquids and Solids)
- Deviations:
- no
- GLP compliance:
- no
- Type of method:
- pycnometer method
- Type:
- relative density
- Density:
- 1.08
- Temp.:
- 20 °C
- Remarks on result:
- other: The relative density was determined to be 1.08 ± 0.01
- Conclusions:
- The density of a 45% solution of choline hydroxide was determined in an OECD 109 guideline study, classified as reliable without restrictions. Hence, the results in general are considered as reliable and can be used for further risk assessment. Although the salt choline hydroxide is a solid compound, it is very hygroscopic and cannot be kept water-free under normal environmental conditions. Furthermore, it is marketed as an 45 % aqueous solution and is therefore the predominantly available form. Hence, it is justified out of scientific reasons and exposure considerations to regard choline hydroxide as aqueous solution. The outcome of this study is considered reasonable and within the scientifically expected ranges, the results are considered as valid because of their reproducibility.
- Executive summary:
The relative density D(20/4) of a 45 % aqueous solution of choline hydroxide was determined according to OECD Guideline 109 (Density of Liquids and Solids / pycnometer method) to be 1.08 ± 0.001 at 20 °C ± 0.9 °C. D(20/4) describes the density of the substance at 20 °C in proportion to the density of water at 4 °C. The determination of the density of the aqueous solution of choline hydroxide is justified out of scientific reasons and exposure considerations and the results are within the scientifically expected range. The study was classified as Klimisch 1 and meets fully the OECD 109 guideline requirements.
Determination of the relative density
Measurements
Density of water at 20°C = 0.99821 g/mL (X); Density of water at 4°C = 1g/mL (Y)
|
Test 1 |
Test 2 |
Weight of pycnometer (A) g |
20.4521 |
22.9409 |
Weight of pycnometer + water (B) g |
44.9200 |
47.8684 |
Weight of pycnometer (A1) g |
20.4518 |
22.9407 |
Weight of pycnometer + test substance (C) g |
46.9254 |
49.8688 |
Calculations Used to Determine Relative Density
Volume of pycnometer (mL) V = (B - A) / X
Density of test substance (g/mL) D1 = (C - A1) / V
Relative density D (20/4) = D1 / Y
Results
Using the values and equations above, the relative density for Tests 1 and 2 were calculated.
Test1 |
Test2 |
|
Volume of pycnometer (mL) (V) |
24.5118 |
24.9722 |
Density of test substance (D1) |
1.0800 |
1.0783 |
Relative Density (D1/Y) |
1.0800 |
1.0783 |
Mean relative density reported as 1.08 ± 0.01 at 20°C ± 0.5°C.
- Reason / purpose for cross-reference:
- reference to same study
Reference
- Endpoint:
- vapour pressure
- Type of information:
- calculation (if not (Q)SAR)
- Remarks:
- Estimated by calculation
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Scientifically accepted calculation method
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- according to guideline
- Guideline:
- other: REACH guidance on QSAR R.6, May 2008
- Deviations:
- not applicable
- Principles of method if other than guideline:
- MPBPWIN program (v 1.43): scientifically accepted calculation method for organic chemicals
- GLP compliance:
- no
- Remarks:
- not applicable
- Type of method:
- other: estimated by calculation
- Key result
- Temp.:
- 25 °C
- Vapour pressure:
- 0 Pa
- Remarks on result:
- other: Modified Grain Method (MPBPWIN v1.43), calculated for pure choline hydroxide
- Temp.:
- 25 °C
- Vapour pressure:
- 2 828.4 Pa
- Remarks on result:
- other: Modified Grain Method (MPBPWIN v1.43), calculated for 45 % aqueous solution of choline hydroxide
- Conclusions:
- The vapour pressure of the pure choline hydroxide was calculated to be 1.43 * E-7 Pa at 25 °C using the Modified Grain method of MPBPWIN program v1.43. For the calculation an estimated boiling point of 415.48 °C (Adapted Stein and Brown method) was used.
As the substance is marketed as an 45 % aqueous solution, the vapour pressure was calculated using Raoult´s law and an experimental vapor pressure value for water of 3172.5 Pa at 25 °C, resulting in a calculated vapour pressure of 2828.4 Pa at 25 °C which is in the scientifically expected range as it is close to the vapour pressure of water. - Executive summary:
Intertek estimated the Vapour presure (as well as melting and boiling point) of Choline hydroxide in 2013 (Intertek, 2013) using MPBPWIN program (v 1.43) made available by the U.S. Environmental Protection Agency. This program requires just the input of the chemical structure of the desired compound by SMILES notation. The calculation is done by three different methods: Antoine, Modified Grain and Mackay, whereby the Modified Grain method is preferentially utilized. By taking this method into account and using an estimated boiling point of 415.48 °C, pure choline hydroxide has a vapour pressure of 1.43 * E-7 Pa at 25 °C.
Using Raoult´s law and an experimental vapor pressure value for water of 3172.5 Pa at 25 °C, the vapour pressure of a 45 % solution of choline hydroxide can be calculated to 2828.4 Pa at 25 °C. The result was gained by a scientifically accepted calculation method.
Results
Running Choline Hydroxide (CAS: 123-41-1) through the EPISUITEMPBPWINtool gave the following:
Predicted BP = 415.48 °C (Adapted Stein and Brown method)
Predicted MP = 160.24 °C (Weighted method derived from 285.48 for Adapted Joback method and 128.93 for Gold and Ogle method)
Predicted VP = 1.43x10-7 Pa at 25 °C (Modified Grain method using the predicted BP and MP).
The EPISUITEMPBPWINdata file is given in Figure 1.
As the Choline base is a 45 % solution of Choline Hydroxide in water, the individual vapour pressure values for each of the components was used to estimate the vapour pressure of the mixture by multiplying the predicted value by the mole fraction for each of the components and then summing together, with a vapour pressure value used for water of 3172.5 Pa at 25 °C.
moles choline hydroxide = 45/121.18 = 0.3713
moles water = 55/18.02 = 3.0522
total moles = 3.4235
mole fraction choline hydroxide = 0.3713/3.4235 = 0.1085
mole fraction water = 3.0522/3.4235 = 0.8915
VPmix = 0.1085*1.43x10-7+ 0.8915*3172.5 = 2828.4 Pa at 25 °C.
- Reason / purpose for cross-reference:
- reference to same study
Reference
- Endpoint:
- partition coefficient
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2013-03-21 to 2013-03-22
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Well-documented guideline study according to OECD 107. The fact that Choline hydroxide was tested as 45 % aqueous solution is not expected to influence the outcome of the partition coefficient testing.
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
- Deviations:
- no
- GLP compliance:
- no
- Type of method:
- shake-flask method to: flask method
- Partition coefficient type:
- octanol-water
- Analytical method:
- other: potentiometric titration
- Type:
- log Pow
- Partition coefficient:
- -2.25
- Temp.:
- 25 °C
- pH:
- 11.3
- Remarks on result:
- other: average out of 6 determinations
- Type:
- log Pow
- Partition coefficient:
- -2.301
- Temp.:
- 25 °C
- pH:
- 11.61
- Remarks on result:
- other: Weight of sample: 18.039 mg, ratio n-octanol:water (ml:ml) = 18:18
- Type:
- log Pow
- Partition coefficient:
- -2.523
- Temp.:
- 25 °C
- pH:
- 11.6
- Remarks on result:
- other: Weight of sample: 18.039 mg, ratio n-octanol:water (ml:ml) = 18:18
- Type:
- log Pow
- Partition coefficient:
- -2.222
- Temp.:
- 25 °C
- pH:
- 11.38
- Remarks on result:
- other: Weight of sample: 12.026 mg, ratio n-octanol:water (ml:ml) = 24:12
- Type:
- log Pow
- Partition coefficient:
- -2.097
- Temp.:
- 25 °C
- pH:
- 11.39
- Remarks on result:
- other: Weight of sample: 12.026 mg, ratio n-octanol:water (ml:ml) = 24:12
- Type:
- log Pow
- Partition coefficient:
- -2.097
- Temp.:
- 25 °C
- pH:
- 10.81
- Remarks on result:
- other: Weight of sample: 3.006 mg, ratio n-octanol:water (ml:ml) = 12:24
- Type:
- log Pow
- Partition coefficient:
- -2.398
- Temp.:
- 25 °C
- pH:
- 10.92
- Remarks on result:
- other: Weight of sample: 3.006 mg, ratio n-octanol:water (ml:ml) = 12:24
- Conclusions:
- The partition coefficient of a 45 % aqueous solution of choline hydroxide was determined according to OECD 107 without restrictions to be -2.25 at 25 °C ± 1 °C. The quality criterion is fulfilled, i.e. the determined values of the partition coefficient of all six replicates expressed as their common logarithms fall within a range of ± 0.3 log units. Due to the ionic structure and rather small molecular weight of the substance, this result is in the scientifically expected range and can be used for further risk assessment.
In addition, the only difference between the test item and the registered substance is an additional amount of 55 % water. This addition is not considered relevant as i.a. the distribution of the compound in water is measured after the establishment of the equilibrium, and hence the logPow of the test item and pure Choline hydroxide are considered be identical (-2.25). - Executive summary:
The water/octanol partition coefficient of a 45 % aqueous solution of choline hydroxide was determined according to OECD 107, shake flask method, without restrictions to be -2.25 at 25 °C ± 1 °C.
The only difference between the test item and the registered substance is an additional amount of 55 % water. This addition is not considered relevant as i.a. the distribution of the compound in water is measured after the establishment of the equilibrium, and hence the logPow of the test item and pure Choline hydroxide are considered be identical (-2.25).
As such, the study was classified as Klimisch 1, fulfills the guideline requirements and the results meet the quality criterion therein.
The stability of Stock Solutions 1, 2, and 3 from which the test solutions were prepared was checked alongside the sample analysis. These solutions were analysed at the end of the partition coefficient test experimental work and the concentration of test substance present was determined. These values were then compared with the theoretical concentrations of the solutions.
A value of 1036 mg/L was determined for Stock Solution 1. Comparison of this value with the theoretical concentration of the solution (1002.15 mg/L) indicates a 103.4 % recovery.
A value of 520 mg/L was determined for Stock Solution 2. Comparison of this value with the theoretical concentration of the solution (501.08 mg/L) indicates a 103.8 % recovery.
A value of 260 mg/L was determined for Stock Solution 3. Comparison of this value with the theoretical concentration of the solution (250.54 mg/L) indicates a 103.8 % recovery.
These values were deemed to show that there has been no significant degradation of the stock solutions in terms of concentration over the test period and therefore the solutions used in the test were considered to have been stable for the duration of the test.
The pH of the water layers and the presaturated water blank was measured on completion of the partition coefficient shake flask test period, using a Sirius GLpH automatic pH meter which was calibrated prior to measurements being performed.
Table 1: Summary of Results
Calculation of Partition Coefficient (SOP 049.02) |
|
|
|
|
|
|
| TEST 1A | TEST 1B | TEST 2A | TEST 2B | TEST 3A | TEST 3B |
Weight of Sample mg | 18.039 | 18.039 | 12.026 | 12.026 | 3.006 | 3.006 |
|
|
|
|
|
|
|
Volume of n-Octanol Saturated Water mLs | 18 | 18 | 24 | 24 | 12 | 12 |
Volume of Water Saturated n-Octanol mLs | 18 | 18 | 12 | 12 | 24 | 24 |
|
|
|
|
|
|
|
Dilution of n-Octanol Layers (If examined neat enter 1) | 1 | 1 | 1 | 1 | 1 | 1 |
Concentration in n-Octanol phase mg/L | 5 | 3 | 3 | 4 | 2 | 1 |
Concentration in n-Octanol phase x dilution mg/L | 5 | 3 | 3 | 4 | 2 | 1 |
Number of mg in n-Octanol phase | 0.090 | 0.054 | 0.036 | 0.048 | 0.048 | 0.024 |
|
|
|
|
|
|
|
Dilution of Water Layers (If examined neat enter 1) | 1 | 1 | 1 | 1 | 1 | 1 |
Concentration in Water phase mg/L | 1058.000 | 1064.000 | 522.000 | 526.000 | 264.000 | 268.000 |
Concentration in Water phase x dilution mg/L | 1058.000 | 1064.000 | 522.000 | 526.000 | 264.000 | 268.000 |
Number of mg in Water phase | 19.044 | 19.152 | 12.528 | 12.624 | 3.168 | 3.216 |
Total Number of mg recovered | 19.134 | 19.206 | 12.564 | 12.672 | 3.216 | 3.240 |
|
|
|
|
|
|
|
p = conc in octanol/conc in water | 0.005 | 0.003 | 0.006 | 0.008 | 0.008 | 0.004 |
Mean P for each test condition | 0.004 |
| 0.007 |
| 0.006 |
|
Mean P for all determinations | 0.006 |
|
|
|
|
|
Standard deviation of individual P from mean P | 0.002 |
|
|
|
|
|
Log P | -2.301 | -2.523 | -2.222 | -2.097 | -2.097 | -2.398 |
Log mean P for all determinations (2dp) | -2.25 |
|
|
|
|
|
|
|
|
|
|
|
|
pH of aqueous layer | 11.61 | 11.66 | 11.38 | 11.39 | 10.81 | 10.92 |
The quality criterion in Guideline 107 for repeatability of results states that the determined values of the partition coefficient expressed as their common logarithms should fall within a range of ± 0.3 log units. All six replicates reported above meet this criterion.
- Reason / purpose for cross-reference:
- reference to same study
Reference
- Endpoint:
- water solubility
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2013-03-11
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: well-documented study (preliminary test / OECD 105 guideline) without deviations
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 105 (Water Solubility)
- Deviations:
- no
- GLP compliance:
- no
- Type of method:
- other: visual inspections
- Water solubility:
- > 90 vol%
- Temp.:
- 22 °C
- pH:
- 14.2
- Remarks on result:
- other: Referring to a 45 % aqueous solution of choline hydroxide; the test item was confirmed as fully miscible
- Water solubility:
- > 486 g/L
- Temp.:
- 22 °C
- pH:
- > 14.2
- Remarks on result:
- other: recalculated via the density of the 45 % solution, which was possible because the test item did not reveal any precipitation from visual inspection
- Conclusions:
- Interpretation of results: very soluble (> 10000 mg/L)
The test substance and all test solutions were observed to contain no precipitate.
The water solubility of test substance Choline Base (as a 45 % aqueous solution) was confirmed as miscible in all proportions. It is therefore reasonable to calculate the water solubility of Choline Base assuming that the test substance is fully soluble in water as a 45 weight % solution in water:
45 weight % is equivalent to 450 g/kg x 1.08 g/L (Density of Test Solution) = 486 g/Litre.
This will be reported as a minimum solubility value of >486 g/Litre. - Executive summary:
The water solubility of a 45 % choline hydroxide (CB) solution was determined in a OECD 105 guideline study by visual inspection. All tested proportions ranging from 1:9 to 9:1 were reported fully miscible and no phase separation occured. Also, choline base as a 45 % solution did not exhibit any visual precipitation. This allows the conclusion that the water solubility of choline hydroxide is > 486 g CB / 1L water, so choline hydroxide is very soluble.
Table 1: All test solution weighings, measurements and observations
Wt sample (g) | Soluble? | % w/w | Miscible? | pH |
1.0019 | 9.0145 | 10.00 | Yes | 13.10 |
2.0218 | 8.0179 | 20.14 | Yes | 13.35 |
3.0082 | 7.0246 | 29.98 | Yes | 13.51 |
4.0043 | 6.0252 | 39.93 | Yes | 13.62 |
5.0325 | 5.0037 | 50.14 | Yes | 13.73 |
6.0116 | 4.0157 | 59.95 | Yes | 13.83 |
7.0120 | 3.0171 | 69.92 | Yes | 13.94 |
8.0046 | 2.0251 | 79.81 | Yes | 14.06 |
9.0044 | 1.0001 | 90.00 | Yes | 14.20 |
pH of distilled water blank = 7.72
In addition the test substance and all test solutions were observed to contain no precipitate.
The water solubility oftest substance Choline Base was confirmed as miscible in all proportions as a 45 weight % solution in water. It is therefore reasonable to calculate the water solubility of Choline Base assuming that the test substance is fully soluble in water as a 45 weight % solution in water:
45 weight % is equivalent to 450 g/kg x 1.08 kg/L (Density of Test Solution) = 486 g/Litre.
This will be reported as a minimum solubility value of >486 g/Litre.
- Reason / purpose for cross-reference:
- reference to same study
Reference
- Endpoint:
- dissociation constant
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- 2013-03-06 to 2013-03-07
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Well documented guideline study (OECD 112) without restrictions.
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 112 (Dissociation Constants in Water)
- Deviations:
- no
- GLP compliance:
- no
- Dissociating properties:
- yes
- No.:
- #1
- pKa:
- 11.2
- Temp.:
- 21.5 °C
- Conclusions:
- The dissociation constant of Choline hydroxide was determined in a OECD 112 guideline study without deviations by titration to be pKa = 11.2 at 21.5 °C. So in general, the results are considered as reliable. However, the results obtained show a strong concentration dependence causing significant variation in the individual pKa results obtained and therefore the calculation of the ideal pKa by extrapolation to zero concentration was performed. As the true pKa value assumes infinite dilution i.e. is a measure of the activity of hydrogen ions, and therefore should not be influenced by surrounding ions, the pKa value to be reported will be that obtained using 0.1M HCl and therefore calculated using the lowest concentrations.
Since due to the alkaline properties of choline base (pH = 14.9 of a 45 % solution), the pKb value is the more relevant one and can be assumed to be pKb = 14.1 – pKa = 2.9, indicating dissociating properties. - Executive summary:
The dissociation constant of Choline hydroxide was determined in a OECD 112 guideline study by titration to be pKa = 11.2 at 21.5 °C.
Results (0.5M sulphuric acid)
As often happens when titrating hydroxides, two end points were detected with a small difference between the two. For the purpose of determination of the dissociation constant, a single equivalence point, to be used to determine the appropriate bracketing measurements, was used, at the mid-point of the curve between the two end points.
Table 1. End Point Titre
Wt. of test substance (g) | Titre (mL) |
0.9918 | 3.7355 |
1.6384 | 6.1741 |
2.4684 | 9.3115 |
Calculation of pKa
The pKa was given by the pH value corresponding to half the volume of titre required to attain the equivalence point. This was calculated in triplicate from the titre/pH value tables generated by the auto-titrator by using the pH of the volumes bracketing the half volume of the end point (4 data points) to prepare a graph and then using the graph to determine the pH at half volume.
Table 2. Raw data for calculation of pKa
Test | End Point Volume (mL) | Half Volume (mL) | Bracketing Volume (mL) | pH |
1 | 3.7355
| 1.8677 | 1.1170 | 12.532 |
1.7070 | 12.419 | |||
2.2230 | 12.281 | |||
2.6430 | 12.131 | |||
2 | 6.1741
| 3.0870 | 1.7960 | 12.668 |
2.4660 | 12.585 | |||
3.0880 | 12.506 | |||
3.7030 | 12.396 | |||
3 | 9.3115 | 4.6557 | 3.9480 | 12.739 |
4.6270 | 12.675 | |||
5.2830 | 12.606 | |||
5.9260 | 12.519 |
Calculation of pKa for Test 1: Y= -0.2606 x 1.8677 + 12.842 = 12.36
Calculation of pKa for Test 2: Y= -0.1409 x 3.0870 + 12.928 = 12.49
Calculation of pKa for Test 3: Y= -0.1105 x 4.6557 + 13.181 = 12.67
Table 3. calculated pKa values
Test | Weight sample (g) | pKa measured |
1 | 0.9918 | 12.36 |
2 | 1.6384 | 12.49 |
3 | 2.4684 | 12.67 |
To calculate the pKa at ideal (zero) weight, a graph is plotted of the pKa values determined versus the weight of test substance and extrapolated to the intercept on the x-axis: extrapolated to zero weight = 12.15, reported as 12.2.
The individual results do vary considerably in accordance with the weight taken indicating a significant concentration dependence. Because of this, it was decided to perform a further triplicate test using lower weights of test substance and using a titrant of 0.1M hydrochloric acid.
Results (0.1M hydrochloric acid)
Again two end points were detected with a small difference between the two. For the purpose of determination of the dissociation constant, a single equivalence point, to be used to determine the appropriate bracketing measurements, was used, at the mid-point of the curve between the two end points.
Table 4: End Point Titre
Wt. of test substance (g) | Titre (mL) |
0.0760 | 2.7602 |
0.1600 | 5.8044 |
0.2934 | 10.5923 |
Calculation of pKa
The pKa was given by the pH value corresponding to half the volume of titre required to attain the equivalence point. This was calculated in triplicate from the titre/pH value tables generated by the auto-titrator by using the pH of the volumes bracketing the half volume of the end point (4 data points) to prepare a graph and then using the graph to determine the pH at half volume.
Table 5. Raw data for calculation of pKa
Test | End Point Volume (mL) | Half Volume (mL) | Bracketing Volume (mL) | pH |
1 | 2.7602
| 1.3801 | 0.7380 | 11.493 |
1.2800 | 11.358 | |||
1.7740 | 11.178 | |||
2.0920 | 10.998 | |||
2 | 5.8044
| 2.9022 | 2.0660 | 11.756 |
2.7270 | 11.641 | |||
3.2000 | 11.569 | |||
3.7770 | 11.472 | |||
3 | 10.5923 | 5.2961 | 3.9580 | 11.919 |
4.6620 | 11.867 | |||
5.3540 | 11.811 | |||
6.0310 | 11.746 |
Calculation of pKa for Test 1: Y= -0.3573 x 1.3801 + 11.782 = 11.29
Calculation of pKa for Test 2: Y= -0.1651 x 2.9022 + 12.095 = 11.62
Calculation of pKa for Test 3: Y= -0.0832 x 5.2961 + 12.252 = 11.81
Table 6: calculated pKa values
Test | Weight sample (g) | pKa measured |
1 | 0.0760 | 11.29 |
2 | 0.1600 | 11.62 |
3 | 0.2934 | 11.81 |
Result extrapolated to zero weight = 11.17, reported as 11.2.
Summary of Results
The results obtained show a strong concentration dependence causing significant variation in the individual pKa results obtained and therefore the calculation of the ideal pKa by extrapolation to zero concentration. As the true pKa value assumes infinite dilution i.e. is a measure of the activity of hydrogen ions, and therefore should not be influenced by surrounding ions, the pKa value to be reported will be that obtained using 0.1M HCl and therefore calculated using the lowest concentrations.
Dissociation constant:11.2 at 21.5 °C
- Reason / purpose for cross-reference:
- reference to same study
Reference
- Endpoint:
- viscosity
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2013-03-06
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: Well documented guideline study (OECD 114) without restrictions.
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- according to guideline
- Guideline:
- OECD Test Guideline 114 (Viscosity of Liquids)
- Deviations:
- no
- GLP compliance:
- no
- Type of method:
- other: rotational rheometer
- Temp.:
- 20°C
- Parameter:
- dynamic viscosity (in mPa s)
- Value:
- 25.3
- Remarks on result:
- other: At 20 °C, the behaviour of the test substance was found to be Newtonian over the measured shear range of 10 to 200 1/s.
- Temp.:
- 40°C
- Parameter:
- dynamic viscosity (in mPa s)
- Value:
- 10.6
- Remarks on result:
- other: At 40 °C, the behaviour of the test substance was found to be Newtonian over the measured shear range of 10 to 200 1/s.
- Conclusions:
- The viscosity of a 45 % solution of choline hydroxide was determined in an OECD 114 guideline study, classified as reliable without restrictions. Hence, the results in general are considered as reliable and can be used for further risk assessment. Although the salt choline hydroxide is a solid compound, it is very hygroscopic and cannot be kept water-free under normal environmental conditions. Furthermore, it is marketed as an 45 % aqueous solution and is therefore the predominantly available form. Hence, it is justified out of scientific reasons and exposure considerations to regard choline hydroxide as aqueous solution, which requires to perform the testing for viscosity instead of a particle size distribution. The outcome of this study is considered reasonable and within the scientifically expected ranges.
- Executive summary:
The viscosity of a 45 % aqueous solution of Choline hydroxide was determined according to OECD Test Guideline 114 (Viscosity of Liquids / rotational viscometer) to be 25.3 mPa.s at 20 °C and 10.6 mPa.s at 40 °C. The determination of the viscosity is justified out of scientific reasons and exposure considerations and the results are within the scientifically expected range. The study was classified as Klimisch 1 and meets fully the OECD 114 guideline requirements.
Raw data of the individual tests
Table 1. Test 1 at 20 °C, Individual Test Result = 25.20 mPa.s
1329003 10468749 T1 @ 20 °C |
|
|
| ||
Time s | Temperature °C | Shear Stress Pa | Shear Rate 1/s | Viscosity Pas | Target Shear Rate 1/s |
50.0 | 20.0 | 0.2498 | 9.955 | 0.02510 | 10.00 |
100.1 | 20.0 | 0.3189 | 12.16 | 0.02623 | 12.21 |
150.1 | 20.0 | 0.3726 | 14.84 | 0.02511 | 14.91 |
200.2 | 20.0 | 0.4550 | 18.12 | 0.02511 | 18.21 |
250.3 | 20.0 | 0.5562 | 22.13 | 0.02513 | 22.23 |
300.4 | 20.0 | 0.6794 | 27.02 | 0.02514 | 27.14 |
350.5 | 20.0 | 0.8303 | 33.00 | 0.02516 | 33.14 |
400.6 | 20.0 | 1.007 | 40.29 | 0.02499 | 40.47 |
450.6 | 20.0 | 1.239 | 49.20 | 0.02518 | 49.42 |
500.7 | 20.0 | 1.517 | 60.07 | 0.02525 | 60.34 |
550.8 | 20.0 | 1.847 | 73.35 | 0.02518 | 73.68 |
600.9 | 20.0 | 2.256 | 89.57 | 0.02519 | 89.97 |
651.0 | 20.0 | 2.757 | 109.4 | 0.02521 | 109.9 |
701.1 | 20.0 | 3.365 | 133.5 | 0.02520 | 134.1 |
751.2 | 20.0 | 4.105 | 163.1 | 0.02518 | 163.8 |
801.3 | 20.0 | 5.024 | 199.1 | 0.02523 | 200.0 |
Table 2. Test 2 at 20 °C, Individual Test Result = 25.43 mPa.s
1329003 10468749 T2 @ 20 °C |
|
|
| ||
Time s | Temperature °C | Shear Stress Pa | Shear Rate 1/s | Viscosity Pas | Target Shear Rate 1/s |
50.02 | 20.0 | 0.2518 | 9.955 | 0.02529 | 10.00 |
100.1 | 20.0 | 0.319 | 12.16 | 0.02624 | 12.21 |
150.2 | 20.1 | 0.3757 | 14.84 | 0.02531 | 14.91 |
200.3 | 20.0 | 0.4585 | 18.12 | 0.02530 | 18.21 |
250.4 | 20.0 | 0.5596 | 22.13 | 0.02528 | 22.23 |
300.5 | 20.0 | 0.6838 | 27.02 | 0.02531 | 27.14 |
350.6 | 20.0 | 0.8353 | 33.00 | 0.02531 | 33.14 |
400.6 | 20.0 | 1.024 | 40.29 | 0.02542 | 40.47 |
450.7 | 20.0 | 1.247 | 49.20 | 0.02535 | 49.42 |
500.8 | 20.0 | 1.528 | 60.07 | 0.02544 | 60.34 |
550.9 | 20.0 | 1.864 | 73.35 | 0.02541 | 73.68 |
601 | 20.0 | 2.276 | 89.57 | 0.02541 | 89.97 |
651.1 | 20.0 | 2.78 | 109.4 | 0.02542 | 109.9 |
701.2 | 20.0 | 3.399 | 133.5 | 0.02545 | 134.1 |
751.3 | 20.0 | 4.153 | 163.1 | 0.02547 | 163.8 |
801.4 | 20.0 | 5.071 | 199.1 | 0.02547 | 200.0 |
Table 3. Test 1 at 40 °C, Individual Test Result = 10.57 mPa.s
1329003 10468749 T1 @ 40 °C |
|
|
| ||
Time s | Temperature °C | Shear Stress Pa | Shear Rate 1/s | Viscosity Pas | Target Shear Rate 1/s |
50.0 | 40.0 | 0.1047 | 9.955 | 0.01052 | 10.00 |
100.1 | 40.0 | 0.1129 | 12.16 | 0.009289 | 12.21 |
150.1 | 40.0 | 0.156 | 14.84 | 0.01051 | 14.91 |
200.2 | 40.0 | 0.1899 | 18.12 | 0.01047 | 18.21 |
250.3 | 40.0 | 0.2316 | 22.13 | 0.01047 | 22.23 |
300.4 | 40.0 | 0.2843 | 27.02 | 0.01052 | 27.14 |
350.5 | 40.0 | 0.3467 | 33.00 | 0.01051 | 33.14 |
400.6 | 40.0 | 0.4352 | 40.29 | 0.01080 | 40.47 |
450.7 | 40.0 | 0.5181 | 49.20 | 0.01053 | 49.42 |
500.8 | 40.0 | 0.6374 | 60.07 | 0.01061 | 60.34 |
550.9 | 40.0 | 0.7769 | 73.35 | 0.01059 | 73.68 |
601.0 | 40.0 | 0.9473 | 89.57 | 0.01058 | 89.97 |
651.1 | 40.0 | 1.158 | 109.4 | 0.01059 | 109.9 |
701.2 | 40.0 | 1.413 | 133.5 | 0.01058 | 134.1 |
751.3 | 40.0 | 1.722 | 163.1 | 0.01056 | 163.8 |
801.4 | 40.0 | 2.111 | 199.1 | 0.01060 | 200.0 |
Table 4. Test 2 at 40 °C, Individual Test Result = 10.56 mPa.s
1329003 10468749 T2 @ 40 °C |
|
|
| ||
Time s | Temperature °C | Shear Stress Pa | Shear Rate 1/s | Viscosity Pas | Target Shear Rate 1/s |
50.02 | 40.0 | 0.1035 | 9.955 | 0.01039 | 10.00 |
100.1 | 40.0 | 0.1399 | 12.16 | 0.01151 | 12.21 |
150.1 | 40.0 | 0.1549 | 14.84 | 0.01043 | 14.91 |
200.2 | 40.0 | 0.1898 | 18.12 | 0.01047 | 18.21 |
250.3 | 40.0 | 0.2321 | 22.13 | 0.01049 | 22.23 |
300.4 | 40.0 | 0.2828 | 27.02 | 0.01047 | 27.14 |
350.5 | 40.0 | 0.3451 | 33.00 | 0.01046 | 33.14 |
400.6 | 40.0 | 0.4308 | 40.29 | 0.01069 | 40.47 |
450.7 | 40.0 | 0.5161 | 49.20 | 0.01049 | 49.42 |
500.8 | 40.0 | 0.6367 | 60.07 | 0.0106 | 60.34 |
550.9 | 40.0 | 0.7745 | 73.35 | 0.01056 | 73.68 |
601 | 40.0 | 0.9434 | 89.57 | 0.01053 | 89.97 |
651 | 40.0 | 1.152 | 109.4 | 0.01054 | 109.9 |
701.1 | 40.0 | 1.408 | 133.5 | 0.01054 | 134.1 |
751.2 | 40.0 | 1.723 | 163.1 | 0.01057 | 163.8 |
801.3 | 40.0 | 2.103 | 199.1 | 0.01056 | 200.0 |
Data source
Reference
- Reference Type:
- study report
- Title:
- Unnamed
- Year:
- 2 013
- Report date:
- 2013
Materials and methods
Test guideline
- Qualifier:
- according to guideline
- Guideline:
- other: OECD 105 water solubility
- Deviations:
- not applicable
- GLP compliance:
- no
Test material
- Reference substance name:
- Choline hydroxide
- EC Number:
- 204-625-1
- EC Name:
- Choline hydroxide
- Cas Number:
- 123-41-1
- Molecular formula:
- C5H14NO.HO
- IUPAC Name:
- choline hydroxide
- Test material form:
- other: liquid
- Details on test material:
- - Name of test material (as cited in study report): Choline Base / Ethanaminium, 2-hydroxy-N,N,N-trimethyl-, hydroxide
- Substance type: Aqueous solution of the pure substance
- Physical state: liquid solution
Constituent 1
Results and discussion
pH valueopen allclose all
- pH value:
- 13.1
- Temp.:
- 21.5 °C
- Concentration:
- 10 other: %(w/w)
- Remarks on result:
- other: %(w/w) referring to a 45 % solution of choline base
- pH value:
- 13.35
- Temp.:
- 21.5 °C
- Concentration:
- 20 other: %(w/w)
- Remarks on result:
- other: %(w/w) referring to a 45 % solution of choline base
- pH value:
- 13.51
- Temp.:
- 21.5 °C
- Concentration:
- 30 other: %(w/w)
- Remarks on result:
- other: %(w/w) referring to a 45 % solution of choline base
- pH value:
- 13.62
- Temp.:
- 21.5 °C
- Concentration:
- 40 other: %(w/w)
- Remarks on result:
- other: %(w/w) referring to a 45 % solution of choline base
- pH value:
- 13.73
- Temp.:
- 21.5 °C
- Concentration:
- 50 other: %(w/w)
- Remarks on result:
- other: %(w/w) referring to a 45 % solution of choline base
- pH value:
- 13.83
- Temp.:
- 21.5 °C
- Concentration:
- 60 other: %(w/w)
- Remarks on result:
- other: %(w/w) referring to a 45 % solution of choline base
- pH value:
- 13.94
- Temp.:
- 21.5 °C
- Concentration:
- 70 other: %(w/w)
- Remarks on result:
- other: %(w/w) referring to a 45 % solution of choline base
- pH value:
- 14.06
- Temp.:
- 21.5 °C
- Concentration:
- 80 other: %(w/w)
- Remarks on result:
- other: %(w/w) referring to a 45 % solution of choline base
- pH value:
- 14.2
- Temp.:
- 21.5 °C
- Concentration:
- 90 other: %(w/w)
- Remarks on result:
- other: %(w/w) referring to a 45 % solution of choline base; this value corresponds to approx. 486 g/L choline base.
Any other information on results incl. tables
Table 1: All test solution weighings, measurements and observations
Wt sample (g) |
Wt water |
% w/w |
Miscible? |
pH |
1.0019 |
9.0145 |
10.00 |
Yes |
13.10 |
2.0218 |
8.0179 |
20.14 |
Yes |
13.35 |
3.0082 |
7.0246 |
29.98 |
Yes |
13.51 |
4.0043 |
6.0252 |
39.93 |
Yes |
13.62 |
5.0325 |
5.0037 |
50.14 |
Yes |
13.73 |
6.0116 |
4.0157 |
59.95 |
Yes |
13.83 |
7.0120 |
3.0171 |
69.92 |
Yes |
13.94 |
8.0046 |
2.0251 |
79.81 |
Yes |
14.06 |
9.0044 |
1.0001 |
90.00 |
Yes |
14.20 |
pH of distilled water blank = 7.72
Applicant's summary and conclusion
- Conclusions:
- The pH value of various choline hydroxide solutions, i.e. different ratios of a 45 % aqueous Choline hydroxide (CB) solution and water, was determined within the water solubility determination of the test item according the preliminary test from the OECD 105 guideline. Although the exact concentrations of choline hydroxide are not known, they can be approximated, for example for the highest concentration tested: A mixture of 90 % of a 45 % choline base solution contains approx. 440 g/L Choline base, which revealed a pH of 14.2.
Consequently, choline base solutions, especially the 45 % Choline hydroxide solution, which is the form placed on the market, are expected to have a very high pH value and can be classified as corrosive without further testing, which has various impacts on risk assessment and necessity of the performance of various testings, which will be individually discussed. - Executive summary:
The pH value of various Choline hydroxide solutions, i.e. different ratios of a 45 % aqueous Choline hydroxide (CB) solution and water, was determined within the water solubility determination of the test item according the preliminary test from the OECD 105 guideline. The exact concentrations of choline hydroxide could be approximated, a mixture of 90 % of a 45 % choline base solution contains approx. 440 g/L choline base, which revealed a pH of 14.2.
The determined pH values are ranging from 13.10 (10 %(w/w) of a 45 % CB solution) to 14.20 (90 %(w/w) of a 45 % CB solution, corresponding to approx. 440 g/L).
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