Amides, from C8-10-fatty acids and tetraethylenepentamine

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

06 November 2015 to 26 July 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

Principles of method if other than guideline:

Preliminary solubility work demonstrated that an emulsion was formed when TEPA C8-10 FA was stirred with water and could not be removed by filtration. This meant that the water solubility was impossible to determine by any of the methods laid down in OECD 105.
An alternative approach to calculate the water solubility was used to give an estimation of the water solubility of TEPA C8-10 FA. The water solubility values were estimated using Estimation Program Interface (EPI Suite™, Ver. 4.11) software developed by the United States Environmental Protection Agency.

The water solubility was calculated for all constituents of the test substance that were stated at 4% of composition or above.
The EPI Suite™, Ver. 4.11software uses two models to predict the water solubility:

WSKOW (v 1.42): this first predicts the partition coefficient, Kow, and then uses this value to estimate the water solubility. Any errors in the prediction of the Kow are carried through to the estimation of water solubility so this method is generally considered the less accurate one.

WATERNT (v 1.01): this uses a fragment method, it breaks the compound (in this case each constituent of the test substance) into different fragments. The solubility of the test substance is then calculated as the sum of the solubilities of the fragments. This method generally gives better predictions of water solubility.

GLP compliance:

yes (incl. QA statement)

Type of method:

other: Preliminary solubility work demonstrated that an emulsion was formed. This meant that the water solubility was impossible to determine by any of the methods laid down in OECD 105.

Key result

Water solubility:

> 0.001 - < 278 750 mg/L

Conclusions:

In conclusion the water solubility of the components within the test substance was considered to range from negligible to very soluble

Executive summary:

Preliminary solubility work demonstrated that an emulsion was formed when TEPA C8-10 FA was stirred with water and could not be removed by filtration. This meant that the water solubility was impossible to determine by any of the methods laid down in OECD 105. An alternative approach to calculate the water solubility was used to give an estimation of the water solubility of TEPA C8-10 FA. The water solubility values were estimated using Estimation Program Interface (EPISuite™, Ver. 4.11) software developed by the United States Environmental Protection Agency.

The water solubility was calculated for all constituents of the test substance that were stated at 4% of composition or above.

The EPISuite™, Ver. 4.11software uses two models to predict the water solubility:

WSKOW (v 1.42): this first predicts the partition coefficient, K_ow, and then uses this value to estimate the water solubility. Any errors in the prediction of the K_oware carried through to the estimation of water solubility so this method is generally considered the less accurate one.

WATERNT (v 1.01): this uses a fragment method, it breaks the compound (in this case each constituent of the test substance) into different fragments. The solubility of the test substance is then calculated as the sum of the solubilities of the fragments. This method generally gives better predictions of water solubility.

General classifications based on water solubility in EPISuite™, Ver. 4.11 are as follows:

Water solubility (mg/L)	Water solubility classification
> 10,000	Very soluble
> 1,000 - 10,000	Very soluble
> 1,000 - 10,000	Soluble
> 100 - 1,000	Moderate solubility
> 0.1 - 100	Slightly soluble
< 0.1	Negligible solubility

Due to these technical issues the water solubility was estimated using EPIWIN software. Several values were calculated for the water solubility based on the different constituents of the test substance.

The stated constituents of the test substance are:

C8FA-TEPA-C10FA (Imidazolines): Typical concentration 22%

C8FA-TEPA-C8FA (Imidazolines): Typical concentration 12%

C10FA-TEPA- C10FA (Imidazolines): Typical concentration 11%

C10FA-TEPA (Imidazoline): Typical concentration 5%

C8FA-TEPA-C10FA (Imidazoline/amide): Typical concentration 4%

C8FA-TEPA-C10FA (Imidazoline/Amide): Typical concentration 5%

C8FA-TEPA (Imidazoline): Typical concentration 6%

C10FA-TEPA (Imidazoline): Typical concentration 5%

C8FA-TEPA (Imidazoline): Typical concentration 4%

C10FA-TEPA-C10FA: Typical concentration 4%

Based on the WATERNT v 1.01 predicted water solubility values, which are generally considered the more reliable, the estimated water solubility values ranged from 0.0014739 mg/L for C10FA-TEPA-C10FA (Imidazolines), which gives a general classification of negligible solubility, to 278750 mg/L for C10FA-TEPA (Imidazoline), which gives a general classification of very soluble.

Description of key information

Study reference SN 321390 shows that the test substance produces emulsions when added to water which could not be removed by centrifugation or filtration. The water solubility was therefore determined on the individual components known in this UVCB using a calculation approach by software EPISUITE (ver. 4.11). This approach led to a wide range of results (0.0014739mg/L to 278750mg/L) which do not accurately describe the properties of the substance.

The study performed on FA TEPA (CAS: 68555 -22 -6) (a structural analogue) showed that this substance forms micelles in water and so the solubility was determined using the critical micelle concentration (CMC) which was 19.0mg/L (pH 7, 23°C). This study has been used as a surrogate as Aradur contains 54% of C18 FA.

Key value for chemical safety assessment

Water solubility:

19 mg/L

at the temperature of:

23 °C