Preconcentration and Separation

Two examples from the analysis of water samples illustrate how a separation and preconcentration can be accomplished simultaneously. In the gas chromatographic analysis for organophosphorous pesticides in environmental waters, the analytes in a 1000-mL sample may be separated from their aqueous matrix by a solid-phase extraction using 15 mb of ethyl acetate. After the extraction, the analytes are present in the ethyl acetate at a concentration that is 67 times greater than that in... 

In order to one of the most effective separation and preconcentration procedure in trace metal analysis is solid phase extraction (SPE) of analyte. 

Horwitz EP, Dietz ML, Chiarizia R, Diamond H, Essling AM, Graczyk D (1992) Separation and preconcentration of uranium from acidic media by extraction chromatography. Anal Chim Acta 266 25-37... 

Horwitz EP, Chiarizia R, Dietz ML, Diamond H, Nelson DM (1993a) Separation and preconcentration of actinides from acidic media by extraction chromatography. Anal Chim Acta 281 361-372 Horwitz EP, Chiarizia, R., Diamond H, Gatrone RC, Alexandratos SD, Trochimzuk AQ, Crick DW (1993b) Uptake of metal ions by a new chelating ion exchange resin. 1. Acid dependencies of actinide ions. Solvent Extr Ion Exch 11 943-966... 

Z. Fang, Flow Injection Separation and Preconcentration, VCH, Weinheim (1993). 

The application of the Chelex 100 resin separation and preconcentration, with the direct use of the resin itself as the final sample for analysis, is an extremely useful technique. The elements demonstrated to be analytically determinable from high salinity waters are cobalt, chromium, copper, iron, manganese, molybdenum, nickel, scandium, thorium, uranium, vanadium, and zinc. The determination of chromium and vanadium by this technique offers significant advantages over methods requiring aqueous final forms, in view of their poor elution reproducibility. The removal of sodium, chloride, and bromide allows the determination of elements with short and intermediate half-lives without radiochemistry, and greatly reduces the radiation dose received by personnel. This procedure was successfully applied in a study of... 

Tapwater, surface water and WWTP effluents were sampled, filtered (0.2pm) and acidified to pH 2.0. REE were separated and preconcentrated following the method described in detail by Bau and Dulski (1996). REE concentrations were determined by inductively coupled plasma mass spectrometry. 

Kiss [8] examined various techniques for the efficient separation and preconcentration of boron from marine sediments. Alkaline fusion with potassium carbonate was used to render boron reactive, even in the most resistant silicate minerals. Fusion cakes were extracted with water and borate was isolated by Amberlite XE-243 boron-selective resin. Borate was determined spectrophotometrically, following elution with 2 mol L 1 hydrochloric acid. Either the carminic acid complex (620nm), formed in sulphuric acid (94%) or sulphuric acetic acid (1 4), or the azomethine hydrogen ion association complex (415nm) formed at pH5.2, were used for borate measurement. 

Abstract A preconcentration method using Amberlite XAD-16 column for the enrichment of aluminum was proposed. The optimization process was carried out using fractional factorial design. The factors involved were pH, resin amount, reagent/metal mole ratio, elution volume and samphng flow rate. The absorbance was used as analytical response. Using the optimised experimental conditions, the proposed procedure allowed determination of aluminum with a detection limit (3o/s) of 6.1 ig L and a quantification limit (lOa/s) of 20.2 pg L, and a precision which was calculated as relative standard deviation (RSD) of 2.4% for aluminum concentration of 30 pg L . The preconcentration factor of 100 was obtained. These results demonstrated that this procedure could be applied for separation and preconcentration of aluminum in the presence of several matrix. 

Horwitz, E. P. Shulz, W. W. Metal Ion Separation and Preconcentration Progress and Opportunities Bond, A. H. Dietz, M. L. Rogers, R. D. Eds., American Chemical Society, 1998. 

Cloud point extraction has been applied to the separation and preconcentration of analytes including metal ions, pesticides, fungicides, and proteins from different matrices prior to the determination of the analyte by techniques such as atomic absorption, gas chromatography, high performance liquid chromatography, capillary zone electrophoresis, etc. 

Miniaturization of HPLC-ICP-MS is an important issue in bioanalytical chemistry when small amounts of sample (e.g., single cells) need to be investigated.33 ICP-MS (with an octopole collision cell) in combination with nano-HPLC (75 pun column) was optimized for the detection of selenopeptides in a selenium-yeast protein digest after 100-fold preconcentration on a C18 capillary precolumn (300 (im column for salt removal and cleanup).34 Under identical separation and preconcentration conditions, electrospray MS/MS (using Nanospray qQqToF-MS - QSTAR from Applied... 

P. Hashemi and Z. Rahmani, A novel homocystine-agarose adsorbent for separation and preconcentration of nickel in table salt and baking soda using factorial design optimisation of the experimental conditions, Talanta, 68(5), 2006, 1677-1682. 

M. D. Granado-Castro, M. D. Galindo-Riano and M. Garcia-Vargas, Separation and preconcentration of cadmium ions in natural water using a liquid membrane system with 2-acetylpyridine benzoylhydrazone as carrier by flame atomic absorption spectrometry, Spectrochim. Acta, Part B, 59(4), 2004, 577-583. 

The handling and disposal problems associated with the use of liquid solvent extractors have resulted in increased attention to the separation and preconcentration of organic compounds in water by collection in synthetic polymers followed by elution with an organic solvent (2). For example, selective collection and concentration of organic bases on methylacrylic ester resin from dilute water samples have been reported (3). Such collection techniques are especially well-suited to flow-injection measurement techniques. In this study, ionizable organic analytes such as salicylic acid and 8-hydroxyquinoline (oxine) were extracted into a polymer and then back extracted by an aqueous solution. Amperometric measurement using a flow-injection technique was employed to monitor the process. 

S. Kagaya, M. Saiki, Z. A. Malek, Y. Araki, and K. Hasegawa, Coprecipitation with Lanthanum Phosphate as a Technique for Separation and Preconcentration of Iron(III) and Lead, Fresenius J. Anal. Chem. 2001,... 

Besides their uses in separation and preconcentration many of the extractable metal chelates are coloured and can be used directly for quantitative spectrophotometric determinations. 

S. Demirci Cekic, H. Filik and R. Apak, Use of an o-aminobenzec acid-functionalized XAD-4 copolymer resin for the separation and preconcentration of heavy metal (II) ions, Anal. Chim. Acta, 505 (2004) 15-24. 

In 1994, Dadfarnia and McLeod described the analysis of uranium in surface waters and sea water using a simple FI system with an alumina column for preconcentration.77 Species eluted from this column were delivered to an ICP-MS as the detector. Also in 1994, Hollenbach et al. described the automation of extraction chromatographic methods based on TRU-Resin and TEVA-Resin to separate and preconcentrate U, Th, and Tc from soil samples, using ICP-MS for detection.49125 In 1996, Aldstadt et al. described the use of FI and extraction chromatography using TRU-Resin to determine U in environmental samples by ICP-MS.78... 

Am determination in urine with on-line separation and preconcentration using FI system ICP-MS 52... 

Actinide isotope analysis method development using FI technique for column separation and preconcentration ICP-MS 138... 

Horwitz, E. P., Dietz, M. L., Chiarizia, R., Diamond, H., Maxwell, S. L., and Nelson, M. R., Separation and preconcentration of actinides by extraction chromatography using a supported liquid anion exchanger Application to the characterization of high-level nuclear waste solutions, Anal. Chim. Acta, 310, 63-78, 1995. 

Dietz, M. L., Yaeger, J., Sajdak, L. R., and Jensen, M. P., Characterization of an improved extraction chromatographic material for the separation and preconcentration of strontium from acidic media, Sep. Sci. Technol., 40, 349-366, 2005. 

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