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Endpoint:
adsorption / desorption
Remarks:
adsorption
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
Sorption experiments with sediment from artificial pond (organic carbon content 22%). Determination of alkyl sulfates using methylene blue assay.
GLP compliance:
no
Type of method:
HPLC estimation method
Media:
sediment
Radiolabelling:
no
Test temperature:
25 °C
Details on study design: HPLC method:
IDENTIFICATION AND QUANTIFICATION OF TEST SUBSTANCE/PRODUCT
- Separation method (e.g. HPLC, GC): Gas chromatography (Perkin-Elmer-F33-Chromatograph with FID)
- Conditions (column, mobile phase, etc.): Glass column (1.5 m x 5 mm), packed with 15% (w/w) ethylene glycol succinate silicone (EGSS-X) on 80-100 mesh Chromosorb
- Detection method (e.g. ECD, UV, MS, ICP-AES, ICP-MS): Injector and detector temperatures 225 °C, carrier gas N2 at a pressure of 280 kN/m2
Analytical monitoring:
yes
Details on matrix:
- Details on collection (e.g. location, depth, contamination history, procedure: obtained from artificial pond through which part of a stream at the Institute of Freshwater Ecology, River Laboratory site may be directed, collection on 20 Nov 1988 and 23 March 1989; using fine mesh sieve (2 mm), dried at 85 °C and passed successively through sieves of 2, 0.319 and 0.125 mm size, organic carbon removed, then treatment of 250 g sediment with 500 mL 0.1M NaOH for 24 hours, filtration of supernatant and subsequent acidification with concentrated HCl to final pH of 1.5
- Textural classification (i.e. %sand/silt/clay): clay, particles <0.125 mm, humic fraction used
- Organic carbon (%): 22.2% by weight, however removed by pretreatment with hydrogen peroxide, resulting in humic fraction
- Specific surface area: 8.24 m2/g with BET c constant of 56.0
- Mineral composition: quartz and calcite, some feldspars and mica
Details on test conditions:
TEST SYSTEM
- Type, size and further details on reaction vessel: Adsorption apparatus: solution in contact with suspended adsorbent was circulated via syringe pump (through 0.1 µm cellulose nitrate filter) via valve K, operated by stepper motor, PTFE tubing was flushed thoroughly before sample was directed to fraction collector J; 200 mL 10 mM NaHCO3 was weighed into the adsorption cell and allowed to come to thermal equilibrium with CO2/N2 mixture to give a pH of 7.6 ± 0.02; Adsorbent was added to the cell and left for 1 h before a sample was removed for analysis; stock solution of AS added from autoburette and after 20 min a sample was removed for analysis; Procedure was repeated with successive additions of AS. Isotherm computed from data retrieved from the autoburette and the surfactant.
Type:
Koc
Value:
> 122 - < 178 dimensionless
Temp.:
25 °C
% Org. carbon:
22
Type:
log Koc
Value:
> 2.09 - < 2.25 dimensionless
Temp.:
25 °C
% Org. carbon:
22

Experimentally derived sediment-water partition coefficients (kd) and sorption coefficients for alkyl sulfates on sediment (Marchesi et al. 1991):

CAS

Chain-length

Kd

Koc

142-31-4

C8

16.7-22.3

75-101

1072-15-7

C9

26.1-32.6

118-147

142-87-0

C10

27.1-39.5

122-178

Not available

C11

76.7-81.7

346-368

151-21-3

C12

70.2-99.1

316-446

3026-63-9

C13

135.0-142.7

608-642

1191-50-0

C14

296.7-347.9

1337-1567

 

Endpoint:
adsorption / desorption: screening
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Remarks:
Summary of available data used for the endpoint assessment of the target substance
Adequacy of study:
key study
Justification for type of information:
Refer to the Category Approach Justification document provided in IUCLID6 Section 13.
Reason / purpose:
read-across source
Type:
Koc
Value:
> 122 - < 178 dimensionless
Temp.:
25 °C
% Org. carbon:
22
Remarks on result:
other: Source, key, 142-87-0, 1991
Type:
log Koc
Value:
> 2.09 - < 2.25 dimensionless
Temp.:
25 °C
% Org. carbon:
22
Remarks on result:
other: Source, key, 142-87-0, 1991

Description of key information

log Koc = 2.09 (experimental data)

Key value for chemical safety assessment

Koc at 20 °C:
122

Additional information

Since no reliable sorption tests are available for Sulfuric acids, C9-11-iso-C10 rich, alkyl esters, sodium salt, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5, a read-across to another structurally related substance was conducted.

In the publication of Marchesi et al. (1991), sediment sorption data for several alkyl sulfates with different carbon chain lengths are presented. The C10AS Na (CAS 142-87-0) is indicated to be of low sorption potential. The determined Koc values are between 122 and 178 which corresponds to log Koc values in the range of 2.09 and 2.25. For the PNEC sediment and soil derivation, according to the equilibrium partitioning method (EPM), the lower boundary of the range (Koc = 122) was taken into account, since this value represents the worst case scenario for the chemical safety assessment.

Due to structural and property similarities with the tested substances it can be concluded that the above results apply also to Sulfuric acids, C9-11-iso-C10 rich, alkyl esters, sodium salt.