Surfactants solid-liquid extraction

With the aim of minimising the time taken in the preconcentration, and extending the chemical analysis of surfactants to more complex aqueous matrices in which very low detection limits are required, preconcentration techniques using solid-liquid extraction with various adsorbent materials, such as XAD [27] and anionic exchange resin [28] have been developed. 

The most important advantage of cloud point extraction is that only small amounts of nonionic or zwitterionic surfactants are required and consequently the procedure is less costly and more environmentally benign than other conventional extraction techniques such as liquid-liquid extraction and solid liquid extraction [107,108]. Moreover, CPE offers the possibility of combining extraction and preconcentration in one step. 

The method of choice for the extraction of surfactants from sewage sludges or sediments is solid-liquid extraction (SLE). In most cases, however, further purification of the extracts is necessary prior to quantitative determination. LAS are desorbed from sewage sludge either in a noncontinuous procedure by extraction into chloroform as ion pairs with methylene blue or in a continuous procedure by the application of a Soxhlet apparatus and addition of solid NaOH to the dried sludge in order to increase extraction efficiency. Heating of sludge or sediment samples in methanol under reflux for 2 h is also sufficient to extract LAS with recoveries of 85%. ... 

A procedure for the determination of diuretics of different therapeutical character high (bumetanide, ethacrynic acid, furosemide), intermediate (bendroflumethiazide, chlorthalidone, hydrochlorothiazide, xipamide) and low (acetazolamide, amiloride, spironolactone, triamterene) efficacy diuretics, and the uricosuric agent probenecid, in urine samples, illustrates a method development implying the control of pH, surfactant and modifier [23]. The greatest analytical problems in the detection of these compounds are basically their wide variety of chemical structures, functional groups and protonation constants. This implies the use of several experimental conditions for their analysis with conventional aqueous-organic mobile phases and laborious liquid-liquid or solid-liquid extraction prior to chromatographic separation. In contrast, the same micellar eluent can produce a satisfactory separation after direct injection. 

Again, it was considered that a separation system was required that was relatively simple to operate which used solvents that were already accepted as additives in the food industry. Though it could be predicted that a liquid-liquid extraction procedure would be extremely difficult to use, because of the nature of the surfactant system, this method after investigation in detail, eventually was discarded in favor of the preferred, solid-liquid extraction procedure. The latter process is outlined in the schematic diagram in Figure 8. 

SOLID-PHASE SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF ANIONIC SURFACTANTS WITHOUT LIQUID-LIQUID EXTRACTION... 

Recent studies, including the use of Microtox and ToxAlert test kits [55,56], were carried out for the determination of the toxicity of some non-ionic surfactants and other compounds (aromatic hydrocarbons, endocrine disruptors) before implementation on raw and treated wastewater, followed by the identification and quantification of polar organic cytotoxic substances for samples with more than 20% inhibition. Furthermore, the study of their contribution to the total toxicity was obtained using sequential solid-phase extraction (SSPE) before liquid chromatography-mass spectrometry (LC-MS) detection. This combined procedure allows one to focus only on samples containing toxic substances. 

The recovery of M2D-C3-0-(E0)n-CH3 after exposure to various solid media has been investigated by API-MS, high performance liquid chromatography light scattering mass detection (HPLC-LSD) and HPLC-APCI-MS methods [10]. Recoveries with extraction immediately following application were determined (surfactant concentration 0.1%, surfactant/solid lOmgg-1) with complete recoveries obtained on all media other than the clays illite and montmorillonite (Table 5.5.2) [10]. 

The characterization of water-soluble components in slurries is one use of SPME with mixed solid-liquid samples. In one application, dried homogenized solid samples (10 mg of sewage sludge or sediment) were slurried in 4 ml of H,0 saturated with NaCl and adjusted to pH 2 with HCl for extraction for 1-15 h, which was followed by desorption into 4 1 methanol/ethanol over 2 min. The extracted compounds were either injected into a liquid chromatograph or fed directly via an electrospray ionization interface to a mass spectrometer with 1 s miz scans from 50-700 or selected-ion monitoring. The major components extracted included phthalates, fatty acids, non-ionic surfactants, chlorinated phenols and carbohydrate derivatives [235]. 

An amino acid, tryptophan, was dissolved in SCF ethane for the first time at the 0.1 wt.% level using AOT and octanol. Solubilities are highly adjustable in the solid-liquid-fluid region, where the partitioning of water and surfactant are variable with pressure. It is possible that this type of adjustability could be used to selectively extract and recover hydrophilic substances such as proteins. It could be used also as a means to recover surfactant for recycle, but further woik is needed to understand these complex systems. 

Paleologos, E.K. and Kontominas, M.G. (2004) On-line solid-phase extraction with surfactant accelerated on-column derivatization and micellar liquid chromatographic separation as a tool for the determination of biogenic amines in various food substrates, Anal. Chem., 76, 1289-1294. 

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. 

Most raw materials and many formulated products can be analysed without isolation of the surfactants. For some purposes, however, e.g. determination of molecular weight by titration, the surfactant must be isolated in a pure form. Liquid-solid extraction is useful for this purpose. It is also sometimes desirable to extract fatty acids, neutral fatty matter and/or weak fatty bases, either to determine them or to prevent interference with some other determination. Liquid-liquid extraction is appropriate for this. A special case is the analysis of structured bleaches, which may contain surfactants in strong hypochlorite. The bleach makes most analytical processes for the surfactants difficult or impossible, and the procedure given below is a useful first step. 

Moradi M,Yamini Y, EsrafiliA, Seidi S (2010) Application of surfactant assisted dispersive liquid-Uquid microextraction for sample preparation of chlorophenols in water samples. Talanta 82 1864-1869. doi 10.1016/j.talanta.2010.08.002, ISSN 0039-9140 Moriwakia H, Harino H, HasMmoto H, Arakawa R, Ohe T, Yoshikura T (2003) Determination of aromatic amine mutagens, PBTA-1 and PBTA-2, in river water by solid-phase extraction followed by liquid chromatography-tandem mass spectrometry. J Chromatogr A 995 239-243. doi 10.1016/S0021-9673(03)00514-4... 

Although the above sugar surfactants found many applications, particularly in cosmetics and personal care products, they are seldom very effective in stabilization of disperse systems against flocculation and/or coalescence. This is due to the reversible nature of adsorption of these molecules at the solid/liquid or liquid/liquid interfaces. For that reason we have developed a polymeric surface-active molecule based on inulin (which is extracted from chicory roots). Inulin is a polydisperse polysaccharide consisting mainly, if not exclusively, of j8(2 1) fructosyl fructose units with normally, but not necessar-... 

While sublation is not necessarily more efficient than liquid-liquid extraction for isolation of individual surfactants, it is preferred in analyzing sewage because emulsions are less likely to form. Sublation is less likely to concentrate impurities than is either liquid-liquid or solid phase extraction. A significant advantage of sublation over solid phase extraction is the ease with which large sample volumes can be handled. 

The technological, environmental, and biological importance of adsorption from solution onto a solid surface can hardly be overestimated. The impact of such phenomena on our everyday lives is evident in such areas as foods and food science, agriculture, cosmetics, pharmaceuticals, mineral ore froth flotation, cleaning and detergency, the extraction of petroleum resources, lubrication, surface protection, and the use of paints and inks. Each of these applications, and many more, would be difficult if not impossible in the absence of the effects of adsorbed surfactants and stabilizers at the solid-liquid interface. 

Albertsson (Paiiition of Cell Paiiicle.s and Macromolecules, 3d ed., Wiley, New York, 1986) has extensively used particle distribution to fractionate mixtures of biological products. In order to demonstrate the versatility of particle distribution, he has cited the example shown in Table 22-14. The feed mixture consisted of polystyrene particles, red blood cells, starch, and cellulose. Liquid-liquid particle distribution has also been studied by using mineral-matter particles (average diameter = 5.5 Im) extracted from a coal liquid as the solid in a xylene-water system [Prudich and Heniy, Am. Inst. Chem. Eng. J., 24(5), 788 (1978)]. By using surface-active agents in order to enhance the water wettability of the solid particles, recoveries of better than 95 percent of the particles to the water phase were obsei ved. All particles remained in the xylene when no surfactant was added. 

---