Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Remarks:

adsorption

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE
Estimation Programs Interface (EPI) Suite for Microsoft Windows, v4.11 (US EPA, 2012)

2. MODEL (incl. version number)
KOCWIN v2.00

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See section 'Test Material'.

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF.

5. APPLICABILITY DOMAIN
See attached QPRF.

6. ADEQUACY OF THE RESULT
- The model is scientifically valid (see attached QMRF).
- The model estimates the KOC for the uncharged molecule at 25 °C; screening information on adsorption (and desorption) is required for substances manufactured or imported in quantities of 10 t/y or more (see also attached QPRF).
- See attached QPRF for reliability assessment.

Principles of method if other than guideline:

The estimation for soil adsorption of the test material was performed with US-EPA software EPWIN/KOCWIN v2.00. Two different models are used for this estimation: the Sabljic molecular connectivity (MCI) method as well as the so-called traditional method, which is based on the LogPow of either 5.38 (lower range value) or 7.44 (higher range value).

GLP compliance:

no

Type of method:

other: QSAR by KOCWIN (v2.0)

Media:

soil

Test temperature:

25 °C (MCI method)

Details on study design: HPLC method:

Not relevant for QSAR

Analytical monitoring:

not required

Details on sampling:

Not relevant for QSAR

Details on matrix:

Not relevant for QSAR

Details on test conditions:

Not relevant for QSAR

Type:

log Koc

Value:

4.22 L/kg

Remarks on result:

other: valid for LogKow of 5.38, for the representative structure. Traditional method

Remarks:

The substance is within the applicability domain of the modelKOCWIN, v2.0.

Type:

log Koc

Value:

5.36 L/kg

Remarks on result:

other: valid for LogKow of 7.44, for the representative structure. Traditional method

Remarks:

The substance is within the applicability domain of the modelKOCWIN, v2.0.

Type:

log Koc

Value:

13.96 L/kg

Remarks on result:

other: for both LogKow values, for the representative structure.

Remarks:

The substance is within the applicability domain of the modelKOCWIN, v2.0. The results obtained with the MCI Method will not be taken into account for the PNEC derivation where the values calculated with the traditional method will be used, as the experimentally determined LogPow is included in this equation.

Details on results (HPLC method):

Not relevant for QSAR

Adsorption and desorption constants:

Not relevant for QSAR

Recovery of test material:

Not relevant for QSAR

Concentration of test substance at end of adsorption equilibration period:

Not relevant for QSAR

Concentration of test substance at end of desorption equilibration period:

Not relevant for QSAR

Transformation products:

not measured

Details on results (Batch equilibrium method):

Not relevant for QSAR

Statistics:

Not relevant for QSAR

For the UVCB substance a representative structure of Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts was used to calculate the organic-normalized sorption coeffcient. The MCI method gives a Koc of 13.96 L/kg for both LogKow values used (lower range value of 5.38 and higher range value of 7.44), whereby the traditional method reveals a value of 4.22 and 5.36 L/kg as result.

A QPRF report has been created for one prediction: Corrected LogKoc (MCI method): 13.96 (Estimated Koc = 1.674e+004 L/kg wet-wt) because summary of the KOCWIN prediction result by LogKow methodology is presented in the QPRF report. The test chemical was assigned as "FALLS within applicability domain" for each prediction.

Validity criteria fulfilled:

not applicable

Conclusions:

The study report describes a scientifically accepted calculation method to determine the soil adsorption coefficient using the US-EPA software KOCWIN v2.00. No GLP criteria are applicable for the usage of this tool and the QSAR estimation is easily repeatable.
The estimation of Koc value, based on LogKow was 4.22 and 5.36 L/kg. Moreover, the value estimated using the MCI method revealed a value of 13.96.

Executive summary:

Log Koc

Experimental Data Was Unable to Attain:

The determination was not carried out using the HPLC screening method, designed to be compatible with Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001 and Method C.19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 as the method was shown not to be applicable.

The HPLC method is not applicable to strong acids. Although calciumsulfonate target substance (Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts)is not an acid, the sulphonate group is the conjugate base to sulphonic acid. When dissolved in a polar solution, the substance will dissociate since it requires an anion exchange column to obtain consistent retention times.However, under environmental conditions, dissociation of the substance is not possible (only in presence of a strong acid).Trial injections were attempted on a cyanopropyl (CN) column with a mobile phase of methanol:water (55:45 v/v) but the peak detected varied in the retention time for each injection separately. It can be assumed, that secondary interactions occurred.

Anionic sulphonate components would need to be analyzed at a pH far below the limits of the test (pH 4.5 to 8.5). However, the adsorption coefficient would then be determined for the dissociated organic component and not for the full, nondissociated structure.

Based on this consideration, the adsorption coefficient of the non-dissociated test substance can be expected to be significantly higher than the value which would result by a HPLC determination.

Therefore, thesoil adsorption was calculated with the computer program KOCWIN. 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 logKow.

Estimate Using Chemical Structures:

For the representative structure of the UVCB substanceReaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts, the traditional method gives 4.22 and 5.36 L/kg as result for the lower range LogKow value of 5.38 and the higher range LogKow value of 7.44, respectively. The MCI method reveals a value of LogKoc of 13.96 L/kg for both LogPow values. The MCI method is taken more seriously into account due to the fact, that it includes improved correction factors.

Estimate Using EUSES while Performing Environmental Risk Assessment

When conduct EUSES modeling, "Predominately hydrophobics" was selected as chemcal class for Koc-QSAR and different results were obtained. The EUSES estimates were used to conduct environmental risk assessment.

The results obtained with the MCI Method will not be taken into account for the PNEC derivation where the values calculated with the traditional method will be used, as the experimentally determined LogPow is included in this equation. As the Log Pow results give a range of 5.38 to 7.44 for the calcium sulfonate target substance, the value of 4.22 L/kg - the Log Koc value calculated using the lower range Log Pow value of 5.38 - will be used for derivation of PNECs as a worst case value.

Description of key information

Experimental procedure is technically not feasible. Prediction with KOCWINv2.00:

logKoc for the representative structure of the calcium sulfonate target substance (Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts):

- 4.22 and 5.36 L/kg (the traditional method, using the lower range LogKow value of 5.38 and the higher range LogKow value of 7.44, respectively).

- 13.96 L/kg (MCI method, using both LogKow values)

The results obtained with the MCI Method will not be taken into account for the PNEC derivation where the values calculated with the traditional method will be used, as the experimentally determined LogPow is included in this equation.

As the Log Pow results give a range of 5.38 to 7.44 for the calcium sulfonate target substance, the value of 4.22 L/kg - the Log Koc value calculated using the lower range Log Pow value of 5.38 - will be used for derivation of PNECs as a worst case value.

Key value for chemical safety assessment

Koc at 20 °C:

91 201 083 935 591

Additional information

Experimental Data Was Unable to Attain:

The determination was not carried out using the HPLC screening method, designed to be compatible with Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001 and Method C.19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 as the method was shown not to be applicable.

The HPLC method is not applicable to strong acids. Although calcium sulfonate target substance (Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts) is not an acid, the sulphonate group is the conjugate base to sulphonic acid. When dissolved in a polar solution, the substance will dissociate since it requires an anion exchange column to obtain consistent retention times. However, under environmental conditions, dissociation of the substance is not possible (only in presence of a strong acid). Trial injections were attempted on a cyanopropyl (CN) column with a mobile phase of methanol:water (55:45 v/v) but the peak detected varied in the retention time for each injection separately. It can be assumed, that secondary interactions occurred.

Anionic sulphonate components would need to be analyzed at a pH far below the limits of the test (pH 4.5 to 8.5). However, the adsorption coefficient would then be determined for the dissociated organic component and not for the full, nondissociated structure.

Based on this consideration, the adsorption coefficient of the non-dissociated test substance can be expected to be significantly higher than the value which would result by a HPLC determination.

Therefore, the soil adsorption was calculated with the computer program KOCWIN. 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 logKow.

Estimate Using Chemical Structures:

For the representative structure of the UVCB substance Reaction products of benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs. para-, calcium salts, the traditional method gives 4.22 and 5.36 L/kg as result for the lower range LogKow value of 5.38 and the higher range LogKow value of 7.44, respectively. The MCI method reveals a value of LogKoc of 13.96 L/kg for both LogPow values. The MCI method is taken more seriously into account due to the fact, that it includes improved correction factors.

Estimate Using EUSES while Performing Environmental Risk Assessment

However, when conduct EUSES modeling, "Predominately hydrophobics" was selected as chemcal class for Koc-QSAR and different results were obtained. The EUSES estimates were used to conduct environmental risk assessment.

[LogKoc: 14.0]