Fractionation procedures

Microwave extraction realized at 120 °C for 30 min with Hexane -Acetone (3 2 V/V) as the extraction solvent was identified as the most effective extraction procedure for isolation of TPH from biotic matrices. The aim of this research is to develop a silica gel and alumina fractionation procedure for plant sample extraction. Column chromatography with two solvents (chloroform and hexane dichloromethane) as a mobile phase were used for clean-up of extract. In this research the efficiency of recovery received from chloroform as a mobile phase. 

This result is of great interest as it means that tedious fractionation procedures can be avoided The polydispersity of a polymer made by an anionic living polymerization is expected to be narrower than that of a very good fraction arising from a sample obtained by other methods. 

Porath, J, Some Recently Developed Fractionation Procedures and Their Application to Peptide and Protein Hormones, Pure and Applied Chemistry 6, 233, 1963. 

Rapidase C-80 (Gist -brocades) was used as enzyme source. The fractionation procedure of the crude preparation included chromatography on Bio-Gel PIO (100-200 mesh), DEAE-Bio-Gel A, and Bio-Gel HTP (Bio-Rad, Richmond, CA, USA). Other column materials used were cross-linked alginate (degree of cross-linking 2.34, prepared in our laboratory). Phenyl Superose HR 5/5 and Mono Q HR 5/5 (Pharmacia Biotech, Uppsala, Sweden). 

Third, the bulk of the items in Table 1 address method performance. These requirements must be satisfied on a substrate-by-substrate basis to address substrate-specific interferences. As discussed above, interferences are best dealt with by application of conventional sample preparation techniques use of blank substrate to account for background interferences is not permitted. The analyst must establish a limit of detection (LOD), the lowest standard concentration that yields a signal that can be differentiated from background, and an LOQ (the reader is referred to Brady for a discussion of different techniques used to determine the LOD for immunoassays). For example, analysis of a variety of corn fractions requires the generation of LOD and LOQ data for each fraction. Procedural recoveries must accompany each analytical set and be based on fresh fortification of substrate prior to extraction. Recovery samples serve to confirm that the extraction and cleanup procedures were conducted correctly for all samples in each set of analyses. Carrying control substrate through the analytical procedure is good practice if practicable. 

Extraction Procedure B. Figure 1 gives a flow diagram for this fractionation procedure, which was based on a modification of the simplified methods described by Serve et al. (20) and Hartley and Buchan (21). Two grams of ground dried sunflower leaves were added... 

In the work now reported coal fractions derived from a solubilised coal were reacted individually with Tetralin, without any additions of catalyst or gaseous hydrogen, and the reaction products studied to determine the effect that chemical type had on the reaction. The untreated whole coal was also reacted to test whether phenol, present in the coal fractions as a result of the fractionation procedure, was having any significant effect on the reaction with the fractions. 

Although sequential fractionation procedures generally do not allow assessing the precise association of elements with each soil mineralogical phase, they can provide operationally defined phase associations and may be a powerful tool for the identification of some of the main binding sites, allowing to assess the potential for remobilisation and bioavailability of arsenic in polluted soils (Wenzel et al. 2001 Martin et al. 2007a). 

The methylene blue reaction can also be used in a fractionation procedure for surfactants. The complexes with methylene blue can be collected in an organic solvent, concentrated, dissolved in methanol, and separated by high-performance liquid chromatography [205]. A variation of this method, permitting the collection of surfactant from large volumes of sample, should be workable in seawater. 

Native factor VIII is traditionally purified from blood donations first screened for evidence of the presence of viruses such as hepatitis B and HIV. A variety of fractionation procedures (initially mainly precipitation procedures) have been used to produce a factor VIII product. The final product is filter-sterilized and filled into its finished product containers. The product is then freeze-dried and the containers are subsequently sealed under vacuum, or are flushed with an inert gas (e.g. N2) before sealing. No preservative is added. The freeze-dried product is then stored below 8 °C until shortly before its use. 

Cell fractionation procedures were fundamental to the biochemical identification of steroid and thyroid hormone receptors in brain as well as in other tissues. Isolation of highly purified cell nuclei from small amounts of tissue from discrete brain regions generally is accomplished with the aid of a nonionic detergent, such as Triton X-100 [7],... 

It is often necessary to assess the efficiency of cell fractionation procedures. Electron microscopy of the prepared fractions is very informative but gives no quantitative indication of the purity of the fraction. It is often easier to measure the relative concentrations of marker enzymes in each fraction (Table 8.9). 

A fractionation procedure has been established and widely applied to studies of humic materials [42-44]. The procedure begins with natural OM (i.e., humus) and uses an aqueous basic solution (e.g., 0.1-0.5 mol/1 NaOH and Na2C03) to solubilize a fraction of the OM. The basic extract is then acidified which causes a precipitate to form, i.e., humic acids (HA). The fraction, which remains in solution, is called fulvic acids (FA). Humin is the name given to the insoluble organic fraction that remains after extraction of humic and fulvic acids. At nearneutral pH (pH 5 - 8), which is characteristic of most natural water, the FA are the most water soluble of these three fractions. HA are somewhat less soluble, with their solubility increasing as the pH increases. Humin is insoluble at all pH values. 

Chemical enrichment and class fractionation procedures vary from laboratory to laboratory. Thus, no universal method for further enrichment and fractionation exists. However, the following provides some specific examples of commonly used... 

Jackson, J.B., Pollock, J.M., Jr., and Rill, R.L. (1979) Chromatin fractionation procedure that yields nucleosomes containing near-stoichiometric amounts of high mobility group nonhistone chromosomal proteins. Biochemistry 18, 3739-3748. 

Humic (HA) and fulvic acids (FA) and Humin (HU) were isolated utilizing the standard method recommended by the International Humic Substances Society (IHSS). Their amounts were obtained by quantifying carbon in each fraction and in each step of the fractionation procedure. 

An alternative method of fraction (see Fig. 2) has been developed which takes advantage of the observation that cleavage of the single disulfide bond induces the dimer - monomer transition of fraction IV (B6, S17, S19). If the fractionation procedure is carried out in the presence of a reducing agent, such as j8-mercapthoethanol, the reduced IV can be reoxidized into the dimer form by oxygen. The choice of the method... 

Zinbo, M., D. Schuetzle, D. P. H. Hsieh, N. Y. Kado, J. M. Dasiey, and L. A. Gundel, An Improved Fractionation Procedure for the Bioassay-Directed Chemical Analysis of Ambient Air Particulate Extracts, Anal. Sci., 8, 461-468 (1992). 

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