Organic compounds in aqueous systems

Hustert, K., Mansour, M., Korte, F. (1981) The EPA Test- a method to determine the photochemical degradation of organic compounds in aqueous systems. Chemosphere 10, 995-998. 

Schwarzenbach, R. P., P. M. Gschwend, and D. M. Imboden, Environmental Organic Chemistry, Wiley, New York, 1993. A fine textbook on the chemistry of synthetic organic compounds in aqueous systems, with Chapter 11 serving as a useful introduction to transport versus reaction control of adsorption reactions. 

Di Paola, A., E. Garcia-Lopez, S. Ikeda, G. Marci, B. Ohtani and L. Palmisano (2002). Photocatalytic degradation of organic compounds in aqueous systems by transition metal doped polycrystalline Ti02. Catalysis Today, 75(1 4), 87-93. 

In the degredation mechanisms of organic compounds in aqueous systems and in the atmosphere, the reaction of OH-radicals gains a considerable importance [ I ]. This degradation follows several simultaneously running mechanisms but may be of quite different character. In the last years aqueous H2O2 solutions played... 

In this chapter, the current and future capabilities of HPLC for the determination of trace organic compounds in aqueous environmental samples will be assessed. This assessment will include approaches to sample cleanup or analyte isolation for those species likely to be candidates for analysis by HPLC. Column technology, as it contributes to the use of HPLC for trace organic analyses, will be surveyed. Finally, detection of the compounds eluting from the system will be examined. The ultimate detector will always adequately identify and measure the compounds of interest. 

A related technique that has come into use in recent years and is similar to SPME is stir-bar sorptive extraction (SBSE). Like SPME, it is a solventless technique allowing not only extraction but also concentration of the analyte of interest. In this technique, a stir bar is coated with a relatively thick layer of polydimethylsiloxane film that is placed in the solution containing the compound of interest, where the compound is adsorbed onto the film. The technique initially has been applied to the extraction and isolation of organic compounds from aqueous systems. An additional advantage is that the thicker film used with SBSE allows for the extraction and isolation of larger masses of analytes. 

It has been shown that amylose forms inclusion complexes with iodine and many kinds of organic compounds in aqueous solution. Thus, the most probable model for the interaction of aunylose with TNS is an inclusion complex. Since cyclodextrins form inclusion complexes with TNS and enhance TNS fluorescence in aqueous solution ( ), it is interesting to compare fluorescence decay parameters for TNS-atmylose system with those for TNS-cyclodextrin systems. The values of lifetimes for amylose are the same as those for Y-cyclodextrin. However, the relative content of the long lifetime for amylose is much smaller than that for Y-cyclodextrin.Y -Cyclodextrin is expected to form both 1 1... 

Irradiation of many organic compounds in aqueous solution gives rise to electron transfer and other types of reaction that are important to the normal functioning of biological systems. Spectra, thermodynamics and kinetics can all be studied. Some examples may be... 

A further extension of the SPME technique is coupling to HPLC (or HPLC-MS), which extends the method to (usually polar) compounds that are not amenable for GC analysis. This is also performed by DI sampling. After extraction, compounds bound to the fiber are extracted by a strong solvent. Note that the much simpler thermal desorption cannot be used, as the compounds to be studied are not volatile. This extraction takes place in a special extraction chamber, connected to a modified Rheodyne or Valeo valve of an HPLC system. To facilitate HPLC analysis, a special, so-called in-tube SPME device has been developed. With this technique, organic compounds in aqueous samples are directly extracted from the sample into the internally coated stationary phase of a capillary column and then desorbed by introducing a moving stream of mobile phase. 

Adsorption from liquids is less well understood than adsorption from gases. In principle the equations derived for gases ought to be applicable to liquid systems, except when capillary condensation is occurring. In practice, some offer an empirical fit of the equilibrium data. One of the most popular adsorption isotherm equations used for liquids was proposed by Freundlich 21-1 in 1926. Arising from a study of the adsorption of organic compounds from aqueous solutions on to charcoal, it was shown that the data could be correlated by an equation of the form ... 

Rohm and Flaas Company has developed Amberlite polymeric adsorbent resins that can be used to remove organic compounds from contaminated groundwater, aqueous wastes, and vapor-phase wastes. Amberlite XAD-4 is a crosslinked polystyrene-type polymer. It is hydrophobic and has no ionic functional groups incorporated into its resin structure. The material is most useful in removing low-molecular-weight organic substances from aqueous systems. Amberlite XAD-4 has been commercially available since the 1970s. 

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