LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals
LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals
LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals
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OECD SIDS <strong>LINEAR</strong> <strong>ALKYLBENZENE</strong> <strong>SULFONATE</strong> (<strong>LAS</strong>)<br />
which are well predicted on the basis of their calculated log P values by<br />
QSAR equations resembling those associated with the polar narcosis<br />
mechanism.<br />
Reference: 1) Roberts, D.W. 1991. QSAR issues in aquatic toxicity of surfactants. The<br />
Science of the Total Environment 10/110:557-568.<br />
2) Roberts, D.W. 1989. Aquatic toxicity of linear alkyl benzene sulphonates<br />
(<strong>LAS</strong>) – A QSAR Approach. Communicaciones presentadas a las Jornada<br />
del Comite Espanol de la Detergencia 20:35-43. Also in J.E. Turner, M.W.<br />
England, T.W. Schulz and N. J. Kwaak (Eds) QSAR 88. Proc. Third Int.<br />
Workshop on Quantitative Structure-Activity Relationships in<br />
Environmental Toxicology 22-26 May 1988, Knoxville, TN, pp. 91-98.<br />
Available from NTIS.<br />
3) Könemann, H. 1981. Quantitative structure-activity relationships in fish<br />
toxicity studies: Part I. Relationships for 50 industrial pollutants. Toxicology<br />
19:209-221.<br />
4) Leo, A.J. and Hansch, C. 1979. Substituent Constants for Correlation<br />
Analysis in Chemistry and Biology, New York.<br />
Reliability: 2 Valid with restrictions. Well documented QSAR analysis.<br />
2.6 WATER SOLUBILITY<br />
A. Solubility<br />
(a)<br />
Value: CMC = 0.1 g/L (C12 <strong>LAS</strong>)<br />
Description: Miscible in water<br />
Method: Surface tension of aqueous solutions of Na<strong>LAS</strong> was measured by an<br />
automated Lauda TE IC by the duNouy ring method. All solutions were<br />
prepared with water passed through a Nanopure water filter system and with<br />
sufficient salt to equalize the ionic strength. Solubility of commercial<br />
Na<strong>LAS</strong> was determined by slowly lowering the temperature in a Fisher<br />
Isotemp incubator over several days and recording the temperature at which<br />
the solutions first turned cloudy (cloud point). Clear points were determined<br />
by raising the temperature slowly over several days and recording when the<br />
solution cleared. The solubility of the C12 narrow-distribution phenyl isomers<br />
was determined by heating a saturated solution to 70°C for 0.5-3 h and then<br />
cooling to 5°C. After equilibrating to room temperature overnight, the<br />
cloudy mixture was centrifuged, and the clear supernatant drawn off,<br />
weighed, and dehydrated to determine percentage solids. The percentage<br />
dissolved was then calculated from the weight loss to the supernatant.<br />
GLP: Yes [ ] No [ ] ? [?]<br />
Test Substance: C12 <strong>LAS</strong> and commercial C11-13 <strong>LAS</strong> (sodium salts)<br />
Remarks: Surface activity increased with increasing average alkyl chain length. Some<br />
decrease in surface tension was observed with increasing phenyl isomer<br />
number, but the range of phenyl isomer distribution of commercial products<br />
is not large enough to significantly alter the surface tension vs. log<br />
concentration plot. Increasing the average alkyl chain length of <strong>LAS</strong><br />
decreases solubility (i.e., increases cloud point). The following table shows<br />
the critical micelle concentration (CMC) for various chain lengths <strong>LAS</strong><br />
tested.<br />
Chain length, isomer composition, dialkyltetralin<br />
sulfonate content<br />
CMC (g/L)<br />
C11 high 2-phenyl, low dialkyltetralinsulfonate 0.120<br />
C11 high 2-phenyl, high dialkyltetralinsulfonate 0.120<br />
<strong>UNEP</strong> PUBLICATIONS 126
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