Choline hydroxide

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption, other

Remarks:

adsorption

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Study period:

18 AUG 2022

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE
OECD QSAR toolbox v4.5

2. MODEL (incl. version number)
KOCWIN v2.01

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
OCCN(O)(C)(C)C

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Please refer to the QMRF attached under 'Attached justification'.

5. APPLICABILITY DOMAIN
Please refer to the QPRF attached under 'Attached justification'.

Guideline:

other: REACH guidance on QSAR R.6

Version / remarks:

May 2008

Principles of method if other than guideline:

Software tool(s) used including version: OECD QSAR toolbox v4.5, EPI Suite v4.11
- Model(s) used: KOCWIN v2.01
- Model description: see field 'Attached justification'
- Justification of QSAR prediction: see field 'Justification for type of information', 'Attached justification'

Specific details on test material used for the study:

OCCN(O)(C)(C)C

Key result

Type:

log Koc

Remarks:

MCI method

Value:

0.158

Remarks on result:

other: no details of temp and pH values

Key result

Type:

Koc

Remarks:

MCI method

Value:

1.438 L/kg

Remarks on result:

other: no details of temp and pH values

Type:

log Koc

Remarks:

Traditional method

Value:

0.829

Remarks on result:

other: log Koc value: - 0.8291. no details of temp and pH values

Type:

Koc

Remarks:

Traditional method

Value:

0.148 L/kg

Remarks on result:

other: no details of temp and pH values

Validity criteria fulfilled:

no

Remarks:

Scientifically accepted calculation method. However, the training set does not include any Quarternary Ammonium salts, therefore the estimation is outside the prediction domain of the program.

Conclusions:

The study report describes a scientifically accepted calculation method to determine the soil adsorption coefficient using the US-EPA software KOCWIN v2.01. No GLP criteria are applicable for the usage of this tool and the QSAR estimation is easily repeatable. The Koc from MCI method is estimated to be 1.438 L/kg, Koc estimation from traditional method calculated to be 0.1482 L/kg.
However, the training set does not include any Quarternary Ammonium salts, therefore the estimation is outside the prediction domain of the program.

Executive summary:

The organic-normalized sorption coefficient for soil (soil adsorption, Koc) of Choline hydroxide was determined with the computer program from US-EPA (EPIWIN software KOCWIN v2.01). This tool estimates the organic carbon-normalized sorption coefficient for soil (and also for sediment), which is designated as Koc. Two different models are used for this estimation: the Sabljic molecular connectivity (MCI) method as well as with the traditional method which is based on logPow. For the substance Choline hydroxide the traditional method gives a Koc of 0.1482 L/kg, whereby the MCI method reveals a value of 1.438 L/kg as result. The MCI method is taken more seriously into account due to the fact, that it includes improved correction factors. 

However, due to the fact that Choline hydroxide is a Quaternary Ammonium Compound (QAC), the adsorption will depend on the cation-exchange capacity of the sorbent and a variety of other parameters. The training set of the KOCWIN software does not include any QACs, therefore, the estimation is outside the prediction domain of the program.

Description of key information

Calculation according to Franco and Trapp (2008): Koc = 137.3 (logKoc = 2.14)

Prediction with KOCWIN v2.01 (EPIWIN software by US-EPA): MCI Method Koc = 1.438 L/kg, MCI Method log Koc: 0.1576. Traditional method Koc = 0.1482 L/kg, Traditional Method log Koc: -0.8291. Low soil adsorption potential. Substance is a QAC, thus adsorption will depend on the cation-exchange capacity of the sorbent and other parameters
RA_CAS 67-48-1_Prediction with SRC PCKOWIN v1.66: Koc = 2.34, logKoc = 0.37 - low soil adsorption potential

Key value for chemical safety assessment

Koc at 20 °C:

137.3

Additional information

At environmentally relevant conditions, choline hydroxide will be present in ionized form (pKa= 11.2 at 21.5 °C, see IUCLID Ch 4.21). Therefore, the adsorption coefficient was calculated according to Franco & Trapp (2008, 2009, 2010) to correct for the charged molecule at pH 5, 7, and 8. This pH range is representative for 98 % of the European soils. The model is not yet validated; in addition, the applicability domain is not clearly defined. Nevertheless, the Koc values of the Franco & Trapp method give a good indication on the adsorption potential of a substance depending on the pH conditions of soil. The method is based on the dissociation constant pKa and the logKow for the uncharged molecule.

The resulting Koc at pH 5-8 is 137.3 L/kg (log Koc: 2.14).

 

The organic-normalized sorption coefficient for soil (soil adsorption, Koc) of Choline hydroxide was determined with the computer program from US-EPA (EPIWIN software KOCWIN v2.01). This tool estimates the organic carbon-normalized sorption coefficient for soil (and also for sediment), which is designated as Koc. Two different models are used for this estimation: the Sabljic molecular connectivity (MCI) method as well as with the traditional method which is based on logPow. For the substance Choline hydroxide the traditional method gives a Koc of 0.1482 L/kg, whereby the MCI method reveals a value of 1.438 L/kg as result. The MCI method is taken more seriously into account due to the fact, that it includes improved correction factors. However, due to the fact that Choline hydroxide is a Quaternary Ammonium Compound (QAC), the adsorption will depend on the cation-exchange capacity of the sorbent and a variety of other parameters. The training set of the KOCWIN software does not include any QACs, therefore, the estimation is outside the prediction domain of the program.

 

Supporting information to confirm a low adsorption potential is given by OECD SIDS Report for the reliable read-across substance Choline chloride (CAS 67-48-1). Both substances are similar in their chemical structure and properties, thus read-across is justified. Please refer to the separate read-across statement (Chemservice S.A., 2013) for further details. In this report, the Koc of Choline chloride was predicted with SRC PCKOWIN v1.66, resulting in Koc value of 2.34 with a corresponding logKoc of 0.37 (BASF AG, 2003). In conclusion, for both, Choline hydroxide as well as for the read-across substance Choline chloride, a low potential for soil adsorption can be expected.

 

[LogKoc: 0.16]