LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
(b)
Type: partition coefficient
Media: sludge
Method: QSAR analysis
Results: Kp (C11 LAS): 1000 L/kg (log Kp = 3.0)
Kp (C12 LAS): 3162 L/kg (log Kp = 3.5)
Kp (commercial C11.6 LAS mixture): 2,512 L/kg
Test Substance: Pure C11 and C12 LAS; and commercial C11.6 LAS
Remarks: The Kp values for C11 and C12 LAS are reported in this study as
experimentally determined by Games et al. (1982), although they actually
appear to be as reported in Games (1982; see 3.3.1 (d) for summary). The Kp
for the commercial C11.6 LAS mixture is calculated by Feijtel et al. using the
reported C11 and C12 values. Also cites as a model input the log Koc from
Traina et al. 1995 (see 3.3.1(b) for summary). These values are consistent
with the experimental results of Temmink and Kapwijk (see 3.3.1(a).
Reference: Feijtel, T.C.J., Struijs, J., and Matthijs, E. 1999. Exposure modelling of
detergent surfactants – Prediction of 90 th -percentile concentrations in The
Netherlands. Environ. Toxicol. Chem. 18:2645-2652.
Reliability: 4 Not assignable (see 3.3.1(e) for Games 1982)
(c)
Type: organic carbon partition coefficient
Media: dissolved humic substances
Method: The association of C10, C12 and C14 LAS with natural and specimen-grade
dissolved humic substances (DHS) was measured with fluorescence
quenching and with ultracentrifugation techniques. Water-soluble organic
carbon (Carlisle-WSOC) was obtained and extracted from 0-0.1 m depth of a
Carlisle muck in northwest Ohio. The acid-soluble fraction (Carlisle-HA)
was suspended, centrifuged, and dialyzed to remove Cl - and to reduce the
polyvalent cation content. The specimen-grade humic acid was purchased
from Aldrich Chemical Company (Aldrich-HA). Suwanee River humic acid
(SRHA) was obtained from the International Humic Substances Society. The
fluorescence quenching followed the method of Guathier et al. (1986).
Aliquots of the humic acid were placed in borosilicate bottles containing
either NaCl, CaCl2, or concentrated synthetic river water, capped and
incubated at 25°C for 18-24 hours, after which an aliquot of C10, C12 or C14
LAS was added and the solutions equilibrated at 25°C for 2 hours. All
treatments were prepared in triplicate. After 2 hours, 3 mL of each sample
solution was placed into cuvettes and the fluorescence of LAS measured with
a Perkin Elmer LS 5B spectrofluorometer. Ultraviolet absorption
measurements were made at 230 and 288 nm with a Beckman DU 6 UV-vis
spectrophotometer. For the second independent analytical method, a batch
ultracentrifugation method was developed. Aliquots of C12 LAS were added
to polyallomer utltracentrifuge tubes containing the humic acid in a
background electrolyte of either NaCl or CaCl2 and allowed to equilibrate at
25°C. All treatments were prepared in triplicate. After 2 hours, the samples
were centrifuged at 141,000 g for 6 hours at 25°C. The supernatants were
decanted and saved for analysis. The walls of the centrifuge tubes were
extracted with CH3OH, which was saved for analysis. The concentration of
C12 LAS in the supernatants and in the CH3OH extracts was determined by
exciting the solutions in cuvettes at 230 nm and the emission intensity
recorded at 288 nm with a Perkin Elmer LS-5B spectrofluorometer. The
quantity of C12 LAS associated with DHS was calculated from the difference
in the initial and final solution concentrations, following the correction for
the quantity of C12 LAS sorbed to the walls of the centrifuge tubes.
UNEP PUBLICATIONS 149