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Linear alkylbenzenesulfonate (LAS) surfactants in a simple test to detect refractory organic carbon (ROC): Attribution of recalcitrants to impurities in LAS
Author(s) -
Kölbener Pius,
Baumann Urs,
Leisinger Thomas,
Cook Alasdair M.
Publication year - 1995
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620140404
Subject(s) - chemistry , impurity , total organic carbon , biodegradation , high performance liquid chromatography , organic matter , carbon fibers , chromatography , environmental chemistry , dodecane , dissolved organic carbon , undecane , degradation (telecommunications) , refractory (planetary science) , organic chemistry , materials science , composite material , telecommunications , computer science , composite number
The standard procedure to examine the biodegradability of a (group of) compound(s) in a trickling filter is a continuous‐flow system. In this test, nondegraded metabolites from a commercial linear alkylbenzenesulfonate (LAS) surfactant are detected (Kölbener, Baumann, Leisinger, and Cook; accompanying paper). This procedure has now been augmented by two phases in closed cycle to give a test for refractory organic carbon (ROC test). First, the concentration of nondegraded metabolites was increased by readdition of LAS to the solution being cycled through the filter. Second, the concentrated residues were further recycled till the net dissolved organic carbon (DOC) stabilised at a finite value and the net released CO 2 stabilised at about zero. The organic compounds remaining at this phase of the experiment were considered recalcitrant and could be examined by global (e.g., DOC) and specific (e.g., HPLC) assays. Four different commercial preparations of LAS were examined, as were the (4‐sulfophenyl)undecane homologue (C 11 ‐LAS), the (4‐sulfophenyl)dodecane homologue (C 12 ‐LAS), and some related compounds. The four commercial LAS preparations contained different levels of impurities (2% to about 17%, according to the producers), which were largely dialkyltetralinesulfonates (DATS) and branched‐chain alkylbenzenesulfonates (bABS). The refractory organic carbon (ROC) remaining after biodegradation varied from 3 to 14%. The results were a characteristic of the LAS under study and were independent of the source of the biomass used in the experiment. Residues were examined by HPLC, and 50 to 100 peaks were observed, which were usually characteristic of the LAS studied. No peak has been conclusively identified. We consider the recalcitrants to represent carboxylated DATS and carboxylated bABS.