Sulfophenyl Carboxylates Research Articles

Occurrence and fate of linear and branched alkylbenzenesulfonates and their metabolites in surface waters in the Philippines

Laguna de Bay in the Philippines is one of the largest freshwater lakes in Asia and is considered a primary source of drinking water, but also receives daily discharges of effluent from both domestic and industrial activities. Branched alkylbenzenesulfonates (ABS), which were banned in Europe and withdrawn from the market in the U.S. since the mid-1960s, but not in Southeast Asia, and linear alkylbenzenesulfonates (LAS) are anionic surfactants used in detergent formulations and are therefore main components of effluent discharges. The presence of both LAS and ABS in several water streams in the catchment area of Laguna de Bay was determined using liquid chromatography-mass spectrometry (LC-MS). The concentration levels of LAS (1.2–73 and 2.2–102 μg l −1) and ABS (1.1–75 and 1–66 μg l −1) in some tributaries of Laguna de Bay and its outlet (Pasig River) to Manila Bay were assessed in December 1999 and March 2000, respectively. The LAS/ABS ratio was calculated as an indication of the extent of the distribution and fate of these surfactants in the surface water. The nearer the location to the metropolitan area of Manila, the higher the levels of LAS and ABS detected in the waters. Moreover, the extent of biodegradation was investigated by monitoring their alkyl homologue distribution and the presence of sulfophenylcarboxylate (SPC) metabolites. Similarly, differences in the levels of SPC and the homologues were apparent at the different sampling points. Presumably, even the quite recalcitrant ABS form SPCs under the conditions present in Southeast Asia. Since wastewater treatment facilities are not well established in developing countries like the Philippines, the call for the use of environmentally friendly chemicals is of even higher significance.

Sperm cell toxicity test using sea UrchinParacentrotus lividuslamarck (Echinodermata: Echinoidea): Sensitivity and discriminatory ability toward anionic and nonionic surfactants

A reliable sperm cell toxicity test procedure has been developed for the Mediterranean sea urchin Paracentrotus lividus. The sensitivity and discriminatory ability of the test were investigated with regard to surfactants and their biotransformation products. Aromatic and aliphatic surfactants of anionic (linear alkylbenzene sulfonates [LAS]) and nonionic (alcohol polyethoxylates [AE] and nonylphenol polyethoxylates [NPE]) types and their aerobic biodegradation products, i.e., sulfophenylcarboxylates (SPC), polyethylene glycols (PEG), carboxylated polyethylene glycols (PEGC), carboxylated AE (AEC), and nonylphenol (NP), were examined in order to elucidate the influence of their molecular structure on toxicity. Experimental results reveal that the sperm cell test showed good discriminatory ability among all tested compounds, median effective concentration (EC50) values differing by about four orders of magnitude. The toxicity of anionic surfactants depends on the length of the alkyl chain and that of nonionic surfactants is due to their length and branching. Much lower toxicity was shown by aerobic biodegradation products in comparison with that of their parent compounds, with the exception of NP. The obtained EC50s were comparable with available literature data and constitute new toxicity data regarding surfactants for sea urchins.

Biotransformation of linear alkylbenzene sulfonate (LAS) by Phanerochaete chrysosporium: oxidation of alkyl side-chain.

The white rot fungus Phanerochaete chrysosporium, which generally mineralizes substituted aromatics to CO2, transformed linear alkylbenzene sulfonate (LAS) surfactants mainly at their alkyl side chain. Degradation of LAS was evidenced by a zone of clearing on LAS-containing agar plates and colorimetric analysis of liquid cultures. Disappearance of LAS was virtually complete within 10 days in low nitrogen (2.4 mM N), high nitrogen (24 mM N) and malt extract (ME) liquid media. After 5 days of incubation in ME medium, transformation of LAS was complete at concentrations < or = 4 mg l(-1), but decreased at higher concentrations. The LAS degradation was not dependent on lignin peroxidases (LiPs) and manganese-dependent peroxidases (MnPs). Mineralization of 14C-ring-LAS to 14CO2 by P. chrysosporium was < 1% regardless of the culture conditions used. Thin layer chromatography and mass spectral analyses indicated that P. chrysosporium transformed LAS to sulfophenyl carboxylates (SPCs) through oxidative shortening of the alkyl side-chains. While LAS disappearance in the cultures was not dependent on LiPs and MnPs, transformation of the parent LAS moieties to SPCs was more extensive in low N medium that favors expression of these enzymes. The SPCs produced in LN cultures were shorter in chain- length than those produced in ME cultures. Also there was a notable shift in the relative abundance of odd and even chain length metabolites compared to the starting LAS particularly in the low N cultures suggesting the possible involvement of processes other than or in addition to beta-oxidation in the chain-shortening process.

Investigations into the formation of sulfophenylcarboxylates (SPC) from linear alkylbenzenesulfonates (LAS) by liquid chromatography/mass spectrometry

Investigations into the formation of sulfophenylcarboxylates (SPC) from linear alkylbenzenesulfonates (LAS) by liquid chromatography/mass spectrometry

Linear Alkylbenzene Sulfonates and Intermediate Products from their Degradation are not Estrogenic

A number of natural and man-made chemicals possess estrogenic activity, i.e., they induce receptor-mediated estrogen dependent responses in vertebrates. Recently, high concentrations of linear alkylbenzene sulfonates (LAS) and intermediate products of LAS biodegradation, sulfophenyl carboxylates (SPC), have been found in the Bay of Cádiz, Spain. Due to their similar chemical properties with the estrogenic alkylphenolpolyethoxylates (APnEO) it has been speculated that LAS and their metabolites have estrogenic effects. The present work addresses the question upon the possible estrogenicity of LAS and LAS metabolites by two in vitro assays: the yeast estrogen receptor assay and the vitellogenin assay with cultured trout hepatocytes. With both bioassays no estrogenic effects were observed for any of the compounds tested.

Determination of parts per trillion level of carboxylic degradation products of linear alkylbenzenesulfonates in coastal water by solid-phase extraction followed by liquid chromatography/ionspray/mass spectrometry using negative ion detection

Long-chain sulfophenyl carboxylate compounds (SPC) with more than five carbon atoms, which are degradation products of linear alkylbenzenesulfonates (LAS), have been isolated by solid-phase extraction (SPE) followed by identification with liquid chromatography/ ionspray—mass spectrometry (LC/ISP-MS). The isolation procedure involved extraction in a C18 minicolumn and subsequently in a strong anionic exchange (SAX) column, the final determination was accomplished by Negative Ion LC/ISP/MS using a two step approach. First, a chromatographic run at a cone voltage of 80 V was performed. At this voltage the major fragment ion corresponded either to m/z 183 (C11 SPC and LAS) or to m/z 170 (C6SPC to C10SPC), and permitted the confirmation of LAS and SPC. The second step involved an extraction cone voltage of 20 V. In this case [M-H]− ion was the base peak for all the studied compounds (LAS and SPC) and was used as a quantitative ion. The linear range of the proposed method varied from 0.4 to 10 ppb with a limit of detection ranging from 2–20 ppt when 250 mL of coastal water were preconcentrated. The present method represents an important advancement for the unequivocal trace determination of the polar degradation products of LAS, SPC, since current established protocols involve either the use of derivatization/gas chromatography-mass spectrometry and/or liquid chromatography with UV detection. By using the protocol described the direct confirmation and quantitative trace determination of both LAS and their polar metabolites SPC is feasible.

Biodegradation of Coproducts of Commercial Linear Alkylbenzene Sulfonate

Dialkyltetralin sulfonate (DATS) and single methyl-branched isomers of linear alkylbenzene sulfonate (iso-LAS) are coproducts that together can range from 1 to 10% of com mercial LAS depending on the manufacturing process. Biodegradation studies using radiolabeled DATS and iso-LAS showed mineralization by indigenous microbial populations in laboratory simulations of aquatic and soil environments. Half-lives ranged from 2 to 20 days, which is rapid enough to suggest that accumulation would not occur in these environments. Upon exposure to laboratory activated sludge treatment, most model iso-LAS compounds showed greater than 98% parent compound removal, extensive mineralization (>50%), and 79−90% ultimate biodegradation (mineralization plus conversion to biomass). Activated sludge treatment of DATS and one of the iso-LAS isomers (methyl group attached to the benzylic carbon of the alkyl chain) resulted in >98% removal, 3−12% ultimate biodegradation and apparent formation of carboxylated biodegradation intermediates that accounted for 88−97% of the original material. These DATS and iso-LAS biodegradation intermediates continued to mineralize in simulated receiving water and soil environments at rates similar to that of sulfophenyl carboxylate (SPC) intermediates of a standard LAS.

Estrogenic activity of surfactants and some of their degradation products assessed using a recombinant yeast screen

AbstractAn estrogen‐inducible screen was developed in yeast (Saccharomyces cerevisiae) in order to assess whether surfactants and their major degradation products are estrogenic. The DNA sequence of the human estrogen receptor (hER) was integrated into the yeast genome, which also contained expression plasmids carrying estrogen‐responsive sequences (ERE) controlling the expression of the reporter gene lac‐Z (encoding the enzyme β‐galactosidase). Thus, in the presence of estrogens, β‐galactosidase is synthesized and secreted into the medium, where it causes a color change from yellow to red. This recombinant strain was used to determine whether representatives of major surfactant classes and some of their principal degradation products possess estrogenic activity. The results were compared to the effects of the main natural estrogen 17β‐estradiol. None of the parent surfactants tested possessed estrogenic activity. However, one class of surfactants, the alkylphenol polyethoxylates, degrade to persistent metabolites that were weakly estrogenic. Another group of degradation products, the sulfophenyl carboxylates, which are derived from the biodegradation of linear alkylbenzene sulfonates, do not appear to possess estrogenic activity.

Submitochondrial particle response to linear alkylbenzene sulfonates, nonylphenol polyethoxylates and their biodegradation derivatives

AbstractThe effects on mitochondrial respiratory parameters of linear alkylbenzene sulfonates (LAS), nonylphenol polyeth‐oxylates (NPEO), and some of their biotransformation products, namely sulfophenyl carboxylates (SPCs), nonylphenol (NP), and nonylphenoxy acetic acid (NP1EC), were recorded by using the in vitro response of submitochondrial particles (SMP) from beef heart. The toxicity of these compounds was estimated by determining their effects on the energy‐coupled reverse electron transfer (RET), which is induced by ATP and succinate at the first site level of the respiratory chain and reduces exogenous NAD+ to NADH. The toxicity of the substances, expressed as the toxicant concentration decreasing the reduction rate of NAD+ to an extent of 50% (EC50), ranged from 0.61 mg/L for a commercial LAS mixture to 18,000 mg/L for individual SPCs; from 1.3 mg/L for NPEO, with an average of 10 ethoxy units, to 8.2 and 1.8 mg/L for NP1EC and NP, respectively. These results were related to the molecular structure of each compound class and compared with the toxicity values obtained by a variety of biological systems currently used for toxicity testing. The acute toxicity data have demonstrated that (a) the SMP bioassay is suitable for reproducing the toxicological response of whole organisms, such as fishes and invertebrates, to the tested chemicals; and (b) the hydrophobic moiety of these compounds plays a significant role in eliciting their toxic effects. From a toxicological standpoint, attention must be paid to the occurrence in natural waters of residual LAS, whereas in the case of NPEO both unaltered surfactant and all biotransformation products need to be identified and quantified.

LAS removal and biodegradation in a wastewater treatment plant

AbstractLinear alkylbenzene sulfonate (LAS) biodegrades easily and loses its tensioactive properties quickly through a primary biodegradation process, as many works of literature testify. Many studies have been carried out in laboratories or in pilot plants, whereas few have been undertaken in a wastewater treatment plant (WWTP). In Italy, unlike in other countries, no detailed investigation has been made so far to establish LAS biodegradation in real WWTP conditions. EniChem Augusta (EA) and Consorzio Po‐Sangone (CPS) have worked together for over two years on this problem, taking into consideration the large (flow rate: approximately 400 × 103 m3/d) and central active sludge WWTP of the metropolitan area of Torino, north of Italy. Specific LAS data have been obtained, using established HPLC techniques, in influent and effluent streams, in the dissolved (waters) and adsorbed (suspended solids and sludges) phases, to reach a complete mass balance. LAS removal &gt;99% and LAS biodegradation of approximately 85% have been observed. Attention also has been given to LAS intermediates of biodegradation, namely the sulfophenyl carboxylates (SPC), using HPLC and GC‐MS techniques, the latter after derivatization. The SPCs have been found present only in the waters and not in the adsorbed phases (SS and sludges).

Metabolism of linear alkylate sulfonate and alkyl benzene sulfonate in albino rats

The metabolism of linear alkylate sulfonate (LAS) and alkyl benzene sulfonate (ABS) was studied in rats. Both compounds were found to be absorbed readily from the gastrointestinal tract. LAS and its metabolites were excreted primarily in the urine while ABS and its metabolites were excreted primarily into the feces by way of the bile. Most of the administered 35S was excreted from the body within 72 hours, and there was no retention of either compound by any of the tissues. The metabolites of LAS that were excreted in the urine were isolated and found to be a mixture of sulfophenyl butanoic and sulfophenyl pentanoic acids. The metabolites of ABS that were excreted in the bile were isolated in two separate fractions. Both fractions were found to contain sulfophenyl carboxylates having carboxylate chains of 11–13 carbon atoms in length. The compounds in one fraction were found to contain 2 double bonds in their alkyl chain, while those in the other fraction contained none. Since the linear alkyl chains of the LAS mixture could be readily catabolized, the metabolites that were formed were sufficiently polar to be excreted in the urine. Because of the high degree of branching of the alkyl chains of the ABS mixture, it was not readily catabolized, and the metabolites retained much of their original lipidlike character. These metabolites were excreted primarily in the bile, not in the urine.