LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
Results: The average Log Koc values over the four DHS materials (Aldrich-HA,
Carlisle-WSOC, Carlisle-HA, and SRHA) for each LAS chain length tested
are:
Log Koc (C10 LAS): 4.02 L/kg
Log Koc (C12 LAS): 4.83 L/kg
Log Koc (C14 LAS): 5.49 L/kg
The data for Ca-saturated Aldrich-HA was linear over the entire
concentration range of DHS, whereas some curvatura was present in the data
from the Ca-saturated SRHA, and considerable deviation from linearity was
apparent in many of the Na-saturated DHS solutions.
Test Substance: C10 LAS (98% purity), C12 LAS (93% purity), and C14 LAS (88% purity),
each synthesized at Procter and Gamble. Uniformly 14 C-ring labeled C10-,
C12- and C14-LAS were obtained from New England Nuclear and were 93.8,
96.3 and 92.5% pure, with specific activities of 26.6, 68.2, and 34.3 µCi/mg,
respectively.
Remarks: Good agreement was obtained with both of the analytical methods, indicating
that both techniques can be used to quantify the effects of DHS on speciation
of LAS in natural waters with certain limitations. LAS-DHS partition
coefficients increased with increasing length of the alkyl chain in the LAS.
These data indicate the significance of nonpolar forces in LAS-organic
matter interactions. Good agreement was found between the partition
coefficients obtained from the two analytical techniques and those calculated
from the response of uptake and depuration studies conducted with fathead
minnows.
Reference: Traina, S.J., McAvoy, D.C. and Versteeg, D.J. 1996. Association of LAS
with dissolved humic substances and its effect on bioavailability. Env. Sci.
Technol. 30:1300-1309.
Reliability: 2 Valid with restrictions
(d)
Type: Adsorption [X]; Desorption [ ]; Volatility [ ]; Other [ ]
Media: water - activated sludge
Method: estimation of Kd with Freundlich equation
Results: The Kd of commercial LAS was between 660 and 5200 L/kg (6 citations),
dependant on organic carbon content and other characteristics of the solid
phase.
Remarks: Concentration in liquid phase between 1 and 80 mg/L.
Reference: Painter, H.A. and Zabel, T.F. 1988. Review of the environmental safety of
LAS. Wrc Medmendham, UK. Report No. CO 1659-M/1/EV 8658.
Reliability: 4 Not assignable
(e)
Type: Adsorption [X]; Desorption [ ]; Volatility [ ]; Other [ ]
Media: water - activated sludge and water - river sediment
Method: Comparison of Kd for LAS C10 to C14 - Year 1982
Results: Adsorption coefficients (L/kg) in activated sludge and river sediment,
respectively, for LAS homologues:
C10: 220 and 41
C11: 1000 and 100
C12: 3070 and 330
C13: 9330 and 990
C14: 2950 (for river sediment – not determined for activated sludge)
Remarks: Kd is highly dependent on the alkyl chain length of LAS with approximately
a factor of 3 increase per carbon and on the position of the phenyl group on
the alkyl chain. The organic carbon content is also an important factor,
varying by a factor of 10 between activated sludge and river sediment.
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