Solid-phase extractions characterization

Carmine extracted from cochineal insects is one of the most used natural colorings for beverages and other foods. Some representative articles refer to isolation and spectrometric analysis or the use of HPLC or capillary electrophoresis (CE) to separate and characterize all cochineal pigments. Its active ingredient, carminic acid, was quantified by rapid HPLC-DAD or fluorescence spectrometry. Carminic acid, used as an additive in milk beverages, was separated within 9 min using a high-efficiency CE separation at pH 10.0 after a previous polyamide column solid phase extraction (SPE), ... 

De la Torre-Carbot K, Jauregui O, Gimeno E, Castellote AI, Lamuela-Raventos RM and Lopez-Sabater M. 2005. Characterization and quantification of phenolic compounds in olive oils by solid-phase extraction, HPLC-DAD, and HPLC-MS/MS. J Agric Food Chem 53(11 ) 4331 —4340. 

La Force, M.J. Fendorf S. (2000) Solid-phase iron characterization during common selective sequential extractions. Soil Sci. Soc. Am. J. 64 1608-1615... 

Conventional radiochemical methods for the determination of long-lived radionuclides at low concentration levels require a careful chemical separation of the analyte, e.g., by liquid-liquid, solid phase extraction or ion chromatography. The chemical separation of the interferents from the long-lived radionuclide at the ultratrace level and its enrichment in order to achieve low detection limits is often very time consuming. Inorganic mass spectrometry is especially advantageous in comparison to radioanalytical techniques for the characterization of radionuclides with long half-lives (> 104 a) at the ultratrace level and very low radioactive environmental or waste samples. 

C18 solid-phase extraction is used to fractionate polyphenolics for their identification and characterization. This technique can eliminate interfering chemicals from crude extracts and produce desirable results for HPLC or other analytical procedures. To obtain a sufficient volume for all analyses, several separations by solid-phase extraction may be performed. The individual fractions need to be combined and dissolved in solvents appropriate for HPLC analysis. In Basic Protocol 2, the application of a current of nitrogen gas for the removal of water from the C18 cartridge is an important step in the selective fractionation of polyphenolics into non-anthocy-anin and anthocyanin fractions. After the collection of non-anthocyanin polyphenolics, no additional work is necessary to elute anthocyanins bound to the C18 solid phase if anthocyanins are not to be determined. 

The most important solid-phase separation materials for column-based separations in modern radioanalytical chemistry are extraction chromatographic materials, and these have been particularly important in automated radioanalytical chemistry. Solid-phase extraction materials based on the covalent attachment of ligands to solid supports also exist, and they have found application in large-scale separation processes for waste or effluent treatment.22 25 They have been commercialized as Analig or SuperLig materials by IBC Advanced Technologies (American Fork, UT). However, they are less well characterized or used for small-column analytical separations. 

After several decades of research, fundamental aspects of the chemical composition and structure of marine organic matter remain elusive. Advances in the chemical characterization of marine organic matter are, in large part, dependent on the development of quantitative methods for its concentration and isolation from seawater. Each of the major methods currently used for the isolation of marine DOM recovers around one-third of the DOM in seawater (solid-phase extractions, using XAD resins or C18 adsorbents, and ultrafiltration). A coupled reverse osmosis-electrodi-alysis method has recently been used to recover an average of 75% 12% of marine DOM from 16 seawater samples however, the method has emerged too recently to have been well tested at this time. 

Simjouw, J.-E, Minor, E. C., and Mopper, K. (2005). Isolation and characterization of estuarine dissolved organic matter Comparison of ultrafiltration and C18 solid-phase extraction techniques. Mar. Chem. 96, 219-235. 

Pichon, V., A.I. Krasnova, and M.C. Hennion. 2004. Development and characterization of an immunoaf-finity solid-phase-extraction sorbent for trace analysis of propanil and related phenylurea herbicides in environmental waters and in beverages. Chromatographia 60 S221-S226. 

Chemical characterization of DOM has been studied extensively, providing a wealth of information regarding its chemical properties [17,20,25,60,64-89]. CDOM is usually characterized as aquatic humic substances, such as humic and fulvic acids, owing to the presence of multiple double bonds in aromatic, aldehyde, and ketone groups. Isolation of humic substances involves their separation by adsorption on macroporous resins (e.g., XAD-8 or XAD-4) and elution at various pH [90]. Humic acids are soluble above a pH of 2, while fulvic acids are soluble at any pH. Solid phase extraction (SPE) onto Cig resin is also employed to isolate CDOM [44,73]. Amador and coworkers have shown that... 

Dereplication and characterization The characteristic binding profile of a compound on a number of solid phase extraction resins can be used for comparative and dereplication purposes. Compounds that bind differently to the same media must be different, and if a series of extracts is suspected of containing the same unknown natural product (e.g., all the extracts possess the same biological activity), the fact that they all exhibit the same binding profile might lead to a decision to first isolate the component from one of the extracts, then use that as a standard with which to examine the other extracts. 

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