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Adsorption / desorption

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Description of key information

Log Koc = 3.5 - 3.9 

Key value for chemical safety assessment

Koc at 20 °C:
3 273

Additional information

Since no reliable adsorption tests are available for C16-18 and C18–unsatd. AS Na (CAS 1394155-71-5), in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read-across to another structurally related category members was conducted. Read-across data are available for the pure AS homologues: C8AS Na (CAS 142-31-4), C10AS Na (CAS 142-87-0), C12AS Na (CAS 151-21-3), C14AS Na (CAS 1191-50-0). In the publication by Marchesi et al. (1991), the experimental sediment sorption data for several alkyl sulfates with different carbon chain lengths are presented. The Koc values for the longer homologues: C16AS Na (CAS 1120-01-0) and C18AS Na (CAS 1120-04-3) were extrapolated from the available data on C8-14 alkyl sulfates.

The determined Koc values are:

- for C8AS Na (CAS 142-31-4) between 75 and 100 which corresponds to log Koc values in the range of 1.88 and 2.0.

- for C10AS Na (CAS 142-87-0) between 122 and 178 which corresponds to log Koc values in the range of 2.09 and 2.25.

- for C12AS Na (CAS 151-21-3) between 316 and 446 which corresponds to log Koc values in the range of 2.5 and 2.65.

- for C14AS Na (CAS 1191-50-0) between 1337 and 1567 which corresponds to log Koc values in the range of 3.13 and 3.19.

- for C16AS Na (CAS 1120-01-0) the extrapolated value of Koc equals 3273 which corresponds to log Koc 3.515.

- for C18AS Na (CAS 1120-04-3) the extrapolated value of Koc equals 8166 which corresponds to log Koc 3.912.

Based on the log Koc values determined for pure C16 and C18 homologues, the log Koc range of C16-18 and C18–unsatd. AS Na (CAS 1394155-71-5) is between 3.515 and 3.912 (Koc values between 3273 and 8166). For the PNEC sediment and soil derivation according to the equilibrium partitioning method (EPM), the lower boundary of the range (Koc = 3273) was taken into account, since this value represents the worst case scenario for the chemical safety assessment.

[LogKoc: 3.5]