Solid-phase extractions carbon-18 adsorbents

A cleanup procedure is usually carried out to remove co-extracted matrix components that may interfere in the chromatographic analysis or be detrimental to the analytical instrument. The cleanup procedure is dependent on the nature of the analyte, the type of sample to be analyzed, and the selectivity and sensitivity of the analytical instrument used in the analysis. Preliminary purification of the sample extracts prior to chromatographic separation involves liquid-liquid partitioning and/or solid-phase extraction (SPE) using charcoal/Celite, Elorisil, carbon black, silica, or aminopropyl-silica based adsorbents or gel permeation chromatography (GPC). 

Zhou, Q., J. Xiao, and W. Wang. 2006. Using multi-walled carbon nanotubes as solid phase extraction adsorbents to determine dichlorodiphenyltrichloroethane and its metabolites at trace level in water samples by high performance liquid chromatography with UV detection. J. Chromatogr. A 1125 152-158. 

Cheng, X.L., Chen, S.H., Wang, X., Liu, C. Single-walled carbon nanotubes as solid-phase extraction adsorbent for the preconcentration and determination of precious metals by ICP-MS. At. Spectrosc. 31, 75-80 (2010)... 

The major disadvantage of solid phase extraction is that it provides a chemically biased view of the DOM reservoir, and seems to preferentially extract compounds with relatively low amounts of N. Other problems include sample contamination by various resins and incomplete elution of adsorbed DOM. SoHd phase extraction remains, however, the only technique capable of reproducibly isolating DOM compounds within the entire range of MWs. Furthermore, the radiocarbon content (A " C) of DOC isolated by XAD resins is depleted relative to the total dissolved inorganic carbon (DIG) reservoir values for XAD isolates are between —300... 

Extract with DCM. Concentrated and loaded onto a dual-stage carbon sorbent trap. SPED Extract with DCM or solid-phase extraction on two adsorbents (C8 and activated carbon), and elute with ethanol Extract with DCM. Wastewater (CLLE)... 

Trace concentrations of triazines in drinking water may be determined by U.S. EPA Method 525.2, which involves a solid-phase extraction followed by GC/MS analysis. Alternatively, such substances may be detected by GC/NPD following liquid-liquid extraction (U.S. EPA Method 507). Pinto and Jardim (2000) have described a method to measure triazine residues in water. Their method involves concentrating the samples with C-18 solid-phase extraction cartridges followed by HPLC analysis using a C-18 column with UV detection at 230 nm. The method was applied to measure atrazine, simazine, cyanazine, and ametryne in water at a detection level of O.l/irg/L. Zhou et al. (2006) used multiwalled carbon nanotubes as the adsorbents for preconcentration of triazines in water followed by their measurement by HPLC with a diode-array detector. The method was used to analyze atrazine and simazine in environmental waters. The authors have reported detection limits of 33 and 9 ng/L, respectively, for these two compounds under their optimal conditions. 

Rudzinski, W., Gierak, A., Leboda, R., and D browski, A. 1995. Studies of properties of complex carbon-silica adsorbents used in sorption-desorption processes (solid-phase extraction). Fresenius J. Anal. Chem. 352 667-672. 

Cai, Y. Jiang, G. liu, J. Zhou, Q. (2003a). Multi walled carbon nanotubes as a solid-phase extraction adsorbent for the determination of bisphenol a, 4-n-nonylphenol, and 4-tert-octylphenol. Analytical Chemistry, 75, 2517-2521. 

Zhao, H. Wang, L. Qiu, Y. Zhou, Z. Zhong, W. Li, X. (2007). Multiwalled carbon nanotubes as a solid-phase extraction adsorbent for the determination of three barbiturates in pork by ion trap gas chromatography-tandem mass sp>ectrometiy (GG/MS/MS) following microwave assisted derivatization. Analytica Chimica Acta,... 

In gas-solid extractions the sample is passed through a container packed with a solid adsorbent. One example of the application of gas-solid extraction is in the analysis of organic compounds for carbon and hydrogen. The sample is combusted in a flowing stream of O2, and the gaseous combustion products are passed through a series of solid-phase adsorbents that remove the CO2 and 1T20. 

In SPE, choice of an appropriate solid phase is based on their possible molecular interactions with the targeted compounds. For historical reasons, reversed-phase type adsorbents have been largely utilized to extract compounds from aqueous samples, given the fact that many of them have been developed already for use in reversed-phase chromatography applications and are commercially available. Ion exchange adsorbents have been used to retain counter ions based on electrostatic interactions. Solid phase adsorbents combining hydrophobic and ionic interactions are also present, for example graphitized carbon black (GCB) obtained by... 

Air samples are usually collected to solid adsorbents such as Tenax, XAD resins, graphitized carbons (e.g. Carbopak), active charcoal, or porous polymers (e.g. Chromosorb). The chemicals are eluted from the adsorbent to a liquid or gas phase by liquid-solid elution or extraction or by thermal desorption. Extraction is the most common method. Thermal desorption can be applied when analysis is by GC (gas chromatography) method, and, recently, the use of automated thermal desorption has been proposed to provide increased sensitivity in GC/MS analysis of a wide range of CWC-related chemicals 8. ... 

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