Separation by organophosphorus

Transition Metal Cation Separations by Organophosphorus Compounds in Liquid Membrane Processes... 

The lanthanides form many compounds with organic ligands. Some of these compounds are water-soluble, others oil-soluble. Water-soluble compounds have been used extensively for rare-earth separation by ion exchange (qv), for example, complexes form with citric acid, ethylenediaminetetraacetic acid (EDTA), and hydroxyethylethylenediaminetriacetic acid (HEEDTA) (see Chelating AGENTS). The complex formation is pH-dependent. Oil-soluble compounds are used extensively in the industrial separation of rare earths by liquid—liquid extraction. The preferred extractants are carboxylic acids, organophosphorus acids and esters, and tetraalkylammonium salts. 

Sulfur is found in many industrial wastes, marine algae, and sediment samples. Sulfur may mask the region of chromatogram, overlapping with peaks of interest. For example, in pesticides analysis, sulfur can mask over many pesticides such as lindane, aldrin, and heptachlor. Sulfur has a solubility similar to the organochlorine and organophosphorus pesticides and it cannot be separated by Florisil cleanup method. 

Acetylcholinesterase is by far the most widely used enzyme in the preparation of biosensors for determining pesticides, both because organophosphorus insecticides and carbamates represent over half of the entire insecticide market and because the acetylcholinesterase commercially available has a high degree of purity and specificity of action and may be paired with many transducers (potentiometric, amperometric) in both flow and nonflow systems [62]. The specific tendency of organophosphorus pesticides and carbamates to inhibit acetylcholinesterase has been exploited for the purpose of determining these compounds, which are first separated by means of HPLC, then detected through a post-column reaction with immobilized acetylcholinesterase [63]. 

Garcia-Rmz, C. et al.. Enantiomeric separation of organophosphorus pesticides by capillary electrophoresis. Application to the determination of malathion in water samples after preconcentration by off-line solid-phase extraction. Anal. Chim. Acta, 543, 77, 2005. 

Marutoiu C, Sarbu C, Vlassa M, et al. 1986. A new separation and identification method of some organophosphorus pesticide by means of temperature programming gradient thin-layer chromatography. Analysis 14 95-98. 

Marutoiu C, Vlassa M, Sarbu C, et al. 1987. Separation and identification of organophosphorus pesticides in water by HPTE. J High Resolution Chromatog Chromatog Comm 19 465-466. 

Absorbance detectors are also commonly used in combination with postcolumn reactors. Here, most issues of detector linearity and detection limit have to do with optimization of the performance of the reactor. In a typical application, organophosphorus compounds with weak optical absorbances have been separated, photolyzed to orthophosphate, and reacted with molybdic acid, with measurement being performed by optical absorbance.58... 

In spite of their toxicity, alkyl phosphites have been used extensively as lubricant additives, corrosion inhibitors, and antioxidants. In addition to their use as intermediates in synthesis, organophosphorus compounds are useful for separating heavy metals by solvent extraction. Several insecticides that were formerly in widespread use are derivatives of organic phosphates. Two such compounds are malathion and parathion. 

The plutonium concentration in marine samples is principally due to environmental pollution caused by fallout from nuclear explosions and is generally at very low levels [75]. Environmental samples also contain microtraces of natural a emitters (uranium, thorium, and their decay products) which complicate the plutonium determinations [76]. Methods for the determination of plutonium in marine samples must therefore be very sensitive and selective. The methods reported for the chemical separation of plutonium are based on ion exchange resins [76-80] or liquid-liquid extraction with tertiary amines [81], organophosphorus compounds [82,83], and ketones [84,85]. 

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