Separation by extraction chromatography

Actinides found as environmental contamination in mosses collected from a bog in the eastern Italian Alps were analyzed after their chemical separation by extraction chromatography (deposited on steel targets) with respect to isotope ratios and their concentration was determined by LA-ICP-MS. Moss samples were contaminated with a variety of actinide isotopes. The detection limits for actinides were determined as 3.6-7.2 x 10 gg for " Am and respectively. The Pu/ Pu isotope ratio (0.212 0.003) was almost constant within experimental error for all samples investigated. Pu contamination in moss samples was mainly the result of global fallout after nuclear weapons tests. " Am was found at the 2x 10 " gg level. This example demonstrates that mosses can be used as bioindicators for environmental contamination. ... 

PiLvio R and Bigkel M (2000) Actinide separations by extraction chromatography. Applied Radiat Isotop 53 273-277. 

Like solvent extraction, separations by extraction chromatography and centrifugal partition chromatography (also known as centrifugal countercurrent chromatography depending on the apparatus used), are based on the partitioning of an analyte between... 

EXTRACTANT CONCENTRATION GRADIENT IN THE AMERICIUM(III) / CURIUM(III) SEPARATION BY COUNTERCURRENT CHROMATOGRAPHY... 

Despite its widespread application [31,32], the kinetic resolution has two major drawbacks (i) the maximum theoretical yield is 50% owing to the consumption of only one enantiomer, (ii) the separation of the product and the remaining starting material may be laborious. The separation is usually carried out by chromatography, which is inefficient on a large scale, and several alternative methods have been developed (Figure 6.2). For example, when a cyclic anhydride is the acyl donor in an esterification reaction, the water-soluble monoester monoacid is separable by extraction with an aqueous alkaline solution [33,34]. Also, fiuorous phase separation techniques have been combined with enzymatic kinetic resolutions [35]. To overcome the 50% yield limitation, one of the enantiomers may, in some cases, be racemized and resubmitted to the resolution procedure. 

Reliable analytical methods are available for determination of many volatile nitrosamines at concentrations of 0.1 to 10 ppb in a variety of environmental and biological samples. Most methods employ distillation, extraction, an optional cleanup step, concentration, and final separation by gas chromatography (GC). Use of the highly specific Thermal Energy Analyzer (TEA) as a GC detector affords simplification of sample handling and cleanup without sacrifice of selectivity or sensitivity. Mass spectrometry (MS) is usually employed to confirm the identity of nitrosamines. Utilization of the mass spectrometer s capability to provide quantitative data affords additional confirmatory evidence and quantitative confirmation should be a required criterion of environmental sample analysis. Artifactual formation of nitrosamines continues to be a problem, especially at low levels (0.1 to 1 ppb), and precautions must be taken, such as addition of sulfamic acid or other nitrosation inhibitors. The efficacy of measures for prevention of artifactual nitrosamine formation should be evaluated in each type of sample examined. 

Further members of this class of alkaloids are the araguspongines K (10) and L (11), isolated from the marine sponge Xestospongia exigua collected at Bayadha, on the Saudi Arabian Red Sea coast [16]. After evaporation of the EtOH extract, it was partitioned between hexanes and MeCN. The polar fraction was subjected to a series of chromatographic separations by column chromatography on silica gel. The structures of both alkaloids 10 and... 

Horwitz EP, Dietz ML, Fisher DE (1991) Separation and preconcentiation of strontinm from biological, environmental, and nuclear waste samples by extraction chromatography nsing a crown ether. Anal Chem 63 522-525... 

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... 

DOE. 1995b. Separation and analysis of actinides by extraction chromatography coupled with alpha liquid scintillation spectrometry. Washington, DC U.S. Department of Energy. NTIS/DE96060013. 

Reduction ofp-methoxybenzaldehyde, typical procedure method A To lithium phenyltel-lurolate prepared from PhLi (2.1 M, 4 8 mL, 10 mmol) and Te (1.27 g, 10 mmol) in THF (30 mL) under Nj is added p-methoxybenzaldehyde (0.272 g, 2 mmol) at -78°C followed by TFA (0.77 mL, 10 mmol). The solution is stirred for a further 2 h, and allowed to warm at room temperature. H O (200 mL) is added and the product is extracted with ether. The extract is dried (Na2S04), evaporated and the residue separated by SiOj chromatography from the formed diphenyl ditellnride, giving p-methoxybenzyl alcohol (0.23 g (93%)). 

Air (NB) Collection in ethanol reaction with concentrated HCl and zinc dust react with sodium salt of 1,2-naphtho-quinone-4 sulfonic acid at pH 8.0 extraction with CCl concentration separation by paper chromatography extraction of fractions with CCl ... 

Allelochemicals found in extracts of such botanical materials as plant leaves can often be well separated by liquid chromatography (LC). Identification of the separated components on-line by mass spectrometry (MS) is of great value because LC has the ability to deliver samples into the ion source of the spectrometer with low or no thermal decomposition. 

Most of the applications of HPLC for protein analysis deal with the storage proteins in cereals (wheat, corn, rice, oat, barley) and beans (pea, soybeans). HPLC has proved useful for cultivar identihcation, protein separation, and characterization to detect adulterations (illegal addition of common wheat flour to durum wheat flour) [107]. Recently Losso et al. [146] have reported a rapid method for rice prolamin separation by perfusion chromatography on a RP POROS RH/2 column (UV detection at 230nm), sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE), and molecular size determination by MALDl-MS. DuPont et al. [147] used a combination of RP-HPLC and SDS-PAGE to determine the composition of wheat flour proteins previously fractionated by sequential extraction. 

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