Extraction methods turbulent flow

In some cases, so called direct plasma injection techniques may be used23 83 104 108 instead of protein precipitation for loading plasma samples onto an HPLC/MS/MS system. Some direct plasma injection systems use a column switching technique in which the plasma is loaded onto an extraction column that retains the small molecules. The other plasma components are sent to waste and the flow is switched so that the small molecules are eluted onto an analytical column that connects to the MS/MS.23 83 108 One variation of the column switching method is turbulent flow chromatography commercialized by Cohesive Technologies (now part of Thermo, San Jose, CA).23... 

The most common (off-line) sample preparation procedures after protein precipitation are solid phase extraction and liquid-liquid extraction. Multiple vendors and available chemistries utilize 96-well plates for solid phase extraction systems and liquid-liquid extraction procedures. Both extraction process can prepare samples for HPLC/MS/MS assay. Jemal et al.110 compared liquid-liquid extraction in a 96-well plate to semi-automated solid phase extraction in a 96-well plate for a carboxylic acid containing analyte in a human plasma matrix and reported that both clean-up procedures worked well. Yang et al.111 112 described two validated methods for compounds in plasma using semi-automated 96-well plate solid phase extraction procedures. Zimmer et al.113 compared solid phase extraction and liquid-liquid extraction to a turbulent flow chromatography clean-up for two test compounds in plasma all three clean-up approaches led to HPLC/MS/MS assays that met GLP requirements. 

Herman J.L., 2002. Generic method for online extraction of drug substances in the presence of biological matrices using turbulent flow chromatography. Rapid Commun Mass Spectrom 16 421. 

The transport rates fj will be determined by the turbulent flow field inside the reactor. When setting up a zone model, various methods have been proposed to extract the transport rates from experimental data (Mann et al. 1981 Mann et al. 1997), or from CFD simulations. Once the transport rates are known, (1.15) represents a (large) system of coupled ordinary differential equations (ODEs) that can be solved numerically to find the species concentrations in each zone and at the reactor outlet. 

Smalley, J., Kadiyala, P., Xin, B., Balimane, P., and Olah, T. (2006). Development of an online extraction turbulent-flow chromatography tandem mass spectrometry method for cassette analysis of Caco-2 cell based bi-directional assay samples. J. Chromatogr. B Ana. Technol. Biomed. Life Sci. 830 270-277. 

Herman, J.L. "Generic Method for On-Line Extraction of Drug Substances in the P esence of Biological Matrices Using Turbulent Flow Chromatography, Rapid Commun. Mass Spectrom. 16,42 W26 (2002). 

To represent these facts in an organized fashion, we start our deliberahons with a brief survey of the dimensionless groups pertinent to mass transfer operahons. One of these, the Biot number Bi, is singled out for a more detailed examination because it serves as an important criterion in mass transfer to and from particles. We next turn to transport coefficients that apply to systems in laminar flow and show how these coefficients are extracted from the solutions of the pertinent partial differenhal equahon (PDE) models. This is followed by an analysis of systems in turbulent flow where the approach of dimensional analysis is used. We describe the method and present the results obtained for some simple geometries, including flow in a pipe and aroimd spheres and cylinders. 

There are many variants on this simple theme. For instance, many other methods for mixing have found use. In a design offered by Lurgi, the phases are mixed in what is essentially an axial flow pump, and then pass down a relatively long pipe where the turbulence of flow keeps the phases mixed while the extraction takes place. In another design, the individual phases are pumped and then join and pass through a static mixer. There are no particular physicochemical reasons for preferring one type of mixer to... 

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