Investigation of the fate of linear alkyl benzenesulfonates and coproductsin a laboratory biodegradation test by using liquid chromatography/mass spectrometry
A. Di Corcia et al., Investigation of the fate of linear alkyl benzenesulfonates and coproductsin a laboratory biodegradation test by using liquid chromatography/mass spectrometry, ENV SCI TEC, 33(22), 1999, pp. 4112-4118
Citations number
24
Categorie Soggetti
Environment/Ecology,"Environmental Engineering & Energy
Major coproducts of commercial mixtures of linear alkyl benzenesulfonate (L
AS) surfactants are dialkyl tetralin-sulfonates (DATS) and methyl-branched
isomers of LAS (iso-LAS). As a total, DATS and iso-LAS can account: for up
to 15% of LAS. Unlike LAS, little and contrasting information on the fate o
f OATS and iso-LAS is available. We have used liquid chromatography/mass sp
ectrometry with an electrospray interface to follow biotransformation of LA
S coproducts. Structure elucidation of their breakdown products was obtaine
d by in-source collision-induced decomposition (CID) spectra. However, meta
bolites of LAS and iso-LAS could not be distinguished from each other by th
eir CID spectra. According to the OECD 301 B protocol, a laboratory biodegr
adation experiment of LAS and coproducts was conducted. OATS were more resi
stant than iso-LAS. to primary biodegradation. Biotransformation of both LA
S-type compounds and DATS produced, besides expected sulfophenyl alkyl mono
carboxylated (SPAC) LAS and sulfoletralin alkylcarboxylated (STAC) DATS met
abolites, significant amounts of dicarboxylated (SPADC and STADC) species.
SPADCs were less persistent than STADCs. After more than 5 months from the
beginning of the experiment, 40% and 35% of the initial amounts of OATS and
iso-LAS, respectively, were not mineralized. About 64% of refractory SPACs
contained 2-5 alkanoyl carbons in the alkyl chain, while the number of alk
anoyl carbons in the free alkyl chains of refractory STACs and STADCs avera
ged respectively 2.4 and 1.1. On the basis of the results of this study and
LAS consumption, we roughly estimated that 200 000 ton of refractory organ
ics is each year dispersed in the environment as the result of use of the a
bove surfactants.