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Environmental fate & pathways

Adsorption / desorption

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Description of key information

log Koc: > 3

Key value for chemical safety assessment

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No studies investigating the adsorption/desorption behaviour of Reaction products resulting from esterification of sucrose with saturated C16-18 (even numbered) fatty acids are available. Due to this complexity and the high variability in the physicochemical properties of the components it is rather difficult to measure a reliable adsorption coefficient. A calculation of a single Koc for the UVCB substance is also not feasible. Thus, log Koc values for main components were calculated using the MCI method of the KOCWIN Program (v2.00), in order to extrapolate the adsorption potential of the UVCB substance based on this data. 

Log Koc values of 3.54 and 4.1 were calculated for two of the main components palmitic acid (CAS 57-10-3) and sucrose monopalmitate (CAS 26446-38-8), respectively (BASF 2014a,b). Palmitic acid showed to be within the applicability domain of the model. The model is only valid for undissociated substances. The pKa of palmitic acid and stearic acid are 4.75 and 4.75, respectively, indicating that these components will exist almost entirely in the anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts.

Sucrose monopalmitate passed the molecular weight and log Kow criterion but failed to be within the applicability domain regarding the maximum number of instances of identified correction factors. Thus, the definite values may not be fully reliable. However, the results indicate a high adsorption potential of the free acids as well as the sucrose monoester components. The adsorption potential of the sucrose di- and triesters is expected to be even higher, due to the greater number of hydrocarbon side chains, which indicate a higher lipophilicity of these components.

Based on this information, it can be assumed that the adsorption potential of Reaction products resulting from esterification of sucrose with saturated C16 -18 (even numbered) fatty acids is high.