Extracting elements

Speciated Components Little information is available for RMs with respect to the chemical forms or species in which elements occur. In the first approximation, bioavaila-ble, extractable, or leachable levels of elements are of interest. Secondly, at a higher degree of sophistication, data on the levels of the actual species or inorganic moieties such as nitrate, ammonium, phosphate, bromide, bromate, iodide, iodate, and molecular species of which the elements are constituents would be of relevance to those conducting mechanistic and speciation research. Reference materials that are certified for extractable elemental concentrations are not available to monitor the usual procedures in soil science based on extraction. 

Figure 4.5. Cumulative sums of extractable elements in soil J3 (CaC03 33.3%) in consecutive steps of the selective sequential dissolution procedure as a function of the cumulative steps. 1 CARB (carbonate) 2 CARB (carbonate) + ERO (easily reducible oxide) 3 CARB + ERO + OM (organic matter) 4 CARB + ERO + OM + RO (reducible oxide) (after Han and Banin, 1995. Reprinted from Cornmun Soil Sci Plant Anal, 26, Han and Banin A., Selective sequential dissolution techniques for trace metals in arid-zone soils The carbonate dissolution step, p 573, Copyright (1995), with permission from Taylor Francis US)...

Extraction Element Years of irrigation with secondary sewage effluents ... 

Soil samples were analyzed for 53, aqua regia extractable elements by ICP-MS/ES. Cadmium, uranium and molybdenum are anomalous over part of the Lisbon field and most of the Lightning Draw Southeast field (Fig. 4). Mercury, lead and organic carbon are also anomalous over both fields. 

The innovation CHIM technology is based on extracting elements at a limited... 

As the field of chemistry developed, so did the interest in the chemistry of soil. This was natural because the early chemists extracted elements from geological sources and, in the broadest sense, from soil itself. In fact, the development of the periodic table required the extraction, isolation, and identification of all of the elements, many of which are found abundantly in soil. 

Simard RR. Ammonium acetate extractable elements. In Carter MR (ed.), Soil Sampling and Methods of Analysis. Boca Raton, FL CRC Press 1993, pp. 39-42. 

Chen et al. [Ill] extracted elemental sulphur from marine sediments with aromatic solvents and determined sulphur in the extract by gas chromatography. 

Having as necessary, dried, homogenized or comminuted the samples, they must now be digested in a suitable reagent to extract elements in a suitable form for chemical analysis. In many organizations we have reached the point where the analyses pass from the hands of the person who took the sample to those of the analytical chemist. In the author s experience, however, it must be emphasized that to ensure best-quality results the whole procedure from, for example, statistically sampling a sediment to the final chemical analysis, should be handled by the same person. 

Soil samples were analyzed for 53 aqua regia extractable elements by Inductively Coupled Plasma Mass Spectrometry and... 

FigurB 24-23 Extracted element chromatograms produced by gas chromatography-inductively coupled plasma-mass spectrometry. Each trace responds to just one element. [From D. Protrock.

Utilization of a part of capillary column as an extraction element and thermal desorption for the release of analytes (Coated Capillary Microextraction - CCME), (Thick Film Open Tabular Trap - TFOT), (Thick Rim Capillary Trap - TFCT)... 

The treatment scheme for the first irradiated targets (8) was based on the TLAHNO-/DTPA system implemented by liquid-liquid extraction. After dissolution of the Pu/Al targets by nitric acid, the solution was adjusted to low acidity by addition of Al(NO-)-. (OH) and then countercurrently contacted with an organic isoiution of the composition 0.64 M TLA.HNO- in dodecane containing 3 vol % 2-octanol. The co-extracted elements are then separated by selective stripping as follows ... 

SBSE can be successfully used in the analysis of environmental samples [93-97] and for food analysis [98, 99]. PDMS is the most commonly used polymer, primarily because of its thermal stability and durability. SBSE has been modified by application of derivatization with different reagents (acetic anhydride, BSTFA, etc) [100-104]. This approach is suitable for the extraction of compounds requiring derivatization. The use of multistep derivatization with several extraction elements (each reaction is performed on a different stir bar) allows efficient extraction, desorption, and chromatographic analysis of compounds with different functional groups (e.g., phenols, steroids, amines, thiazoles, ketones). Acetic anhydride (ester formation), ethyl chloroformate (reaction of acids and amines), tetraethyloborane, and sodium bis-trimethylotrifluoroacetamide have been used for extraction and simultaneous derivatization [105]. 

Davy invented a method for extracting elements from compounds that were difficult to separate by usual methods. He first passed an electric current through the compound, causing it to melt. The electric current then caused the compound to break apart into the elements of which it is made. 

Frasch process Named for the German-American chemist Herman Frasch (1851-1914), a method to extract elemental sulfur by melting the sulfur with superheated water (at 170°C under high pressure) and forcing it to the surface of the Earth as a slurry. 

One promising method of extracting elements from sea water uses marine organisms. Many marine animals concentrate certain elements in their bodies at levels many times higher than the levels in sea water. Vanadium, for example, is taken up by the mucus of certain tunicates and can be concentrated in these animals to more than 280,000 times its concentration in sea water. Other marine organisms can concentrate copper and zinc by a factor of about 1 million. If these animals could be cultivated in large quantities without endangering the ocean ecosystem, they could become a valuable source of trace metals. 

Sequential extraction schemes have been designed for the determination of binding forms of trace metals in sediment [21] and increasingly used over the last ten years. The lack of uniformity of these schemes, however, did not allow the results to be compared worldwide or the procedures to be validated which led to critical comments [22]. Indeed, the results obtained e.g. by sequential extraction are operationally defined, i.e. the forms of metals are defined by the determination of extractable elements using a given procedure. Therefore, the significance of the analytical results is related to the extraction scheme used. 

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