Fractionation aqueous environmental samples

Fractionation of Residue Organic Compounds from Aqueous Environmental Samples... 

Figure 1. Schematic of the strategy for the coupled bioassay-analytical fractionation of residue organics isolated from aqueous environmental samples.

Lukasewycz, M.T. and Durhan, E.J. (1992) Strategies for the identification of non-polar toxicants in aqueous environmental samples using toxicity-based fractionation and gas chromatography-mass spectrometry, Journal of Chromatography 580, 215-28. 

Commoner, B., A. J. Vithayathil, and P. Dolara, Mutagenic Analysis of Complex Samples of Aqueous Effluents, Air Particulates, and Foods, in Application of Short-Term Bioassays in the Fractionation and Analysis of Complex Environmental Mixtures (M. D. Waters, S. Nesnow, J. L. Huisingh, S. Sandhu, and L. Claxton, Eds.), pp. 529-570, Plenum, New York, 1979. 

T HE SEPARATION, CONCENTRATION, AND FRACTIONATION of organic solutes in aqueous solutions by reverse osmosis are of practical interest from the points of view of water purification and collection of samples for environmental analysis. Although many experimental data on the separation of organic solutes are available in the literature (1-2), very few fundamental works have been accomplished so far. We have been studying this subject in the framework of the preferential sorp-... 

Electrochemical methods have been used for determinations of species of elements in natural waters. Of the many electrochemical techniques, only a few have proved to be useful for studies of speciation in complex samples, and to possess the sensitivity required for environmental applications. The greatest concern is the measurement of the toxic fraction of a metal in an aqueous sample. The definition of a toxic fraction of a metal is that fraction of the total dissolved metal concentration that is recognised as toxic by an aquatic organism. Toxicity is measured by means of bioassays. Elowever, a universally applicable bioassay procedure cannot be adopted because the responses of different aquatic species to metal species vary. Nevertheless, bioassays should be used as means of evaluation and validation of speciation methods. A condition is that the test species (of the bioassay) should be very sensitive to the metals being studied so as to simulate a worst case situation (Florence, 1992). 

When the separation-collection procedure is not quantitative, a radiotracer of the element being determined can be added to the initial sample to serve as a collection monitor. For example, in the determination of gold in low-grade ores, radioactive Au is added to the ore prior to dissolution and subsequent collection on chelate-resin-loaded paper. The intensity of the Pt K x-rays from the K-capture decay of the Au is a linear function of the fraction of gold collected on the resin-loaded paper. Radiotracers of osHg and CHa ° Hg are used to determine the collection efficiency for inorganic and organic mercury in aqueous effluents. The actual chemical form in which the mercury is present, as well as the total mercury content, is an important parameter in environmental studies. 

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