Benzene, mono-C10-13-alkyl derivs., distn. residues, sulfonated, barium salts

Adsorption / desorption

Description of key information

Experimental procedure is technically not feasible.

Prediction with KOCWINv2.00:

logKoc for the representative structure of the barium sulfonate target substance (Benzene, mono-C10-13-alkyl derivs., distn. residues, sulfonated, barium salts):

- 3.8809 L/kg (the traditional method, using the weighted mean LogKow value of 4.76).

- 14.39 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 weighted mean Log Pow result of 4.76 for the barium sulfonate target substance, the value of 3.8809 L/kg - the Log Koc value calculated using the weighted mean Log Pow value of 4.76 - will be used for derivation of PNECs as a worst case value.

Key value for chemical safety assessment

Koc at 20 °C:

7 601

Additional information

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 barium sulfonate target substance (Benzene, mono-C10-13-alkyl derivs., distn. residues, sulfonated, barium 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.

For the representative structure of the UVCB substance Benzene, mono-C10-13-alkyl derivs., distn. residues, sulfonated, barium salts, the traditional method gives 3.8809 L/kg as result for the weighted mean ange LogKow value of 4.76. The MCI method reveals a value of LogKoc of 14.391 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.

[LogKoc: 14.39 (MCI method]

[LogKoc: 3.8809 (Traditional method)]

[LogKoc: 3.88]