Biodegradable intermediate

Di Corcia A, C Crescenzi, A Marcomini, R Samperi (1998) Liquid-chromatography-electrospray-mass spectrometry as a valuable tool for characterizing biodegradation intermediates of branched alcohol ethoxyl-ate surfactants. Environ Sci Technol 32 711-718. 

Staples CA, Naylor CG, Williams JB, Gledhill WE (2001) Ultimate biodegradation of alkylphenol ethoxylates surfactants and their biodegradation intermediates. Environ Toxicol Chem 20 2450-2455... 

Other biodegradation intermediates, such as sulfophenyl carboxy-lates (SPCs) and alkyltetralin carboxylates, can also be analysed by this method. In the latter case, the carboxylates are converted into their acid chlorides and, in a second step, into their trifluoroethyl derivatives as... 

The simultaneous determination of LAS and its potential biodegradation intermediates of low molecular weight (C < 8), as sulfonated and non-sulfonated, has been performed by RP-HPLC-UV using a gradient regime with the mobile phase at pH 2.2 [29]. Compound elution with the same number of carbon atoms in the carboxylic chain was as follows SPCs, hydrophenyl carboxylic acids and finally phenylcarboxylic acids. 

For the characterisation of the biodegradation intermediates of C12-LAS, metabolised in pure culture by an a-proteobacterium, Cook and co-workers [23] used matrix-assisted laser desorption/ionisation (MALDI)-time of flight (TOF)-MS as a complementary tool to HPLC with diode array detection and 1H-nuclear magnetic resonance. The dominating signal in the spectrum at m/z 271 and 293 were assigned to the ions [M - H] and [M - 2H + Na]- of C6-SPC. Of minor intensity were the ions with m/z 285 and 299, interpreted to be the deprotonated molecular ions of C7- and C8-SPC, respectively. 

However, as far as we know, the distribution of LAS biodegradation intermediates according to depth in the sediment column has been determined only in marine sediments [58]. This study was performed in a saltmarsh channel (Sancti Petri Channel, Cadiz Bay, Spain), receiving untreated urban wastewater effluents. In this zone the benthic organisms are very scarce [59], and the capacity for irrigation of... 

Primary biodegradation intermediates (SPC), some of them termed key intermediates of LAS degradation [22], have received less attention, as a consequence of their standards being unavailable, and because until relatively recently no suitable method of recovery was available. 

Cationic surfactants are used widely as fabric softeners, anti-static agents, antiseptic components and as the main ingredients in rinse conditioner products. However, there is little data on their occurrence in wastewater and removal during wastewater treatment. The concentrations of some cationic surfactants and their biodegradation intermediates, found in WWTP influents and effluents, are listed in Table 6.1.3. 

Several specific studies have been made on the LAS transport processes in a variety of different estuarine and marine environmental compartments (e.g. LAS removal by biodegradation and/or adsorption), including the flux of LAS from freshwater to a coastal environment [3,6, 29,40]. However, a complete study of LAS behaviour requires knowledge of their primary biodegradation intermediates, SPC, that have been detected in different laboratory tests [15,36,37], Their existence in fresh-water [2,13] and marine water [5] has been demonstrated recently. 

Although the occurrence of the non-ionic surfactant nonylphenol ethoxylate (NPEO Fig. 6.7.1) and its biodegradation intermediates in the aquatic environment has attracted large interest [18] because of the potential of some biotransformation products to mimic estrogenic effects, their fate and distribution in soil environments has been only investigated in a few cases. 

We examined the relationship between changes in surface tension and changes in toxicity and studied the toxicity of biodegradation intermediates of surfactants. 

This means that the toxicity of its biodegradation intermediates should be higher than that of the original surfactant. 

Table XI Toxicity of Biodegradation Intermediates of Nonionic Surfactants to Fish (14)...

Linear alkylbenzene, sulphonates, dialky ltetraline sulphonates, and biodegradation intermediates Electron capture Derivativisation then electron capture GC-MS [194]... 

Catechol is an important biodegradative intermediate of aromatic xenobiotics. List biochemical reactions that involve catechol. 

Ozone alone oxidizes phenoHc compounds to carbon dioxide and water. However, at concentrations of 1.5—2.5 parts ozone per part of phenol, the phenohc compounds can be converted to less toxic and biodegradable intermediates in a cost-effective manner (35). 

Linear alkylbenzenesulfonates (LAS), alcohol ethoxylates (AEO), and nonylphenol ethoxylates (NPEO) are synthetic surfactants used in the formulation of detergents and other cleaning products and are widely applied in the dye and leather industry and other industrial processes. These compounds, considered as estrogenic, have aroused considerable interest due to the large quantities produced globally. Their low volatility and anionic form make LC-based methods the preferred approach [7]. Due to the presence of different positional isomers, to the biodegradation intermediates, and to the lack of reference standards, LC-MS, and in particular with ESI, is the only technique which enables their identification and quantification in environmental waters. 

Di Corcia, A., Samperi, R., and Marcomini, A. 1994. Monitoring aromatic surfactants and their biodegradation intermediates in raw and treated sewages by solid-phase extraction and liquid chromatography. Environ. Sci. Tech., 28 850-858. 

Methods involving the use of LC-MS to analyze anionic surfactants such as household detergents and their metabolites have rapidly emerged. LC-MS provides access to the polar metabolites and biodegradation intermediates of surfactants, some of which escaped previous investigations based on GC-MS after derivatization. 

Work has mainly been directed towards LAS, as these are still the most widely consumed group of anionic surfactants. Several studies on the detection of LAS in raw and treated sewage have been published, together with their biodegradation intermediates, the SPC, and the byproducts, dialkyl tetraline sulfonates, in laboratory degradation experiments. These compounds have also been detected in sewage treatment, surface water, and coastal water. As with all... 

The metabolic fate of RDX was studied in a mixed culture incubated under methanogenic conditions. Analysis by HPLC confirmed the loss of RDX and the formation of mono-, di-, and trinitroso-RDX as transient biodegradation intermediates. An additional peak observed in the HPLC chromatogram was identified by LC-MS as hydroxylamino-dinitroso-l,3,5-triazine <2001ETC1874>. 

LC-MS methodologies applying TSP interfacing for unequivocal identification of isomers, oligomers and homologues of surfactants and their biodegradation intermediates in environmental samples at trace levels have been reviewed [28] very extensively [23, 40]. 

Several review papers have reported on the application of ESI in the analysis of surfactants. Di Corcia reviewed LC-MS methods for the unequivocal identification of isomers, oligomers and homologues of the technical blends of surfactants and their biodegradation intermediates in environmental samples at trace levels with particular attention to ESI and TSP apphcations [40]. Qench et al. [28] described the applications of LC-MS in environmental analysis using the interfaces PBI, TSP, APCI and ESI in use or just coming into use in th early 1990s. 

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