Sephadex LH-20 gel

Purity is an indispensable requirement of any sensitizer in a dye-sensitized solar cell. While well worked out procedures exist for the efficient purification of metal complexes, we found that the isolation of the complexes at their isoelectric point, followed by column purification using Sephadex LH-20 gel, resulted in analytically pure samples. 

Chemical fractionation of whole products and by-products from synthetic fuel production affords a logical first step in the evaluation of these materials for biological activity and the subsequent prediction of health hazards. Aliphatic and aromatic hydrocarbons, along with smaller amounts of heteroatomic species, constitute the bulk of all crude product materials and define a primary class separation need. Subfractionation of these fractions can lead to identification of bioactive components, Aliphatics are separated from the entire sample by a simple liquid chromatographic elution scheme. Aromatic compounds can be isolated by a cyclo-hexane-dimethylsulfoxide solvent partitioning scheme, A Sephadex LH-20 gel separation scheme appears feasible for the fractionation of crude liquids into aliphatic-aromatic, lipophilic-hydrophilic, polymeric, and hydrogen bonding classes of compounds. 

Table II. Fractionation and Recovery of Shale Oil Lipophilic Fractions Using Sephadex LH—20 Gel...

Isolation of potential anticancer compounds from bioactive extracts involves bioactivity-guided fractionation. The DNA-damaging natural products encountered in our studies were extracted by MEK and/or methanol, and the general methodology which we have employed in our bioassay-directed fractionation of these extracts is schematically presented in Fig. 7. These fractionations involved solvent-solvent partition, Sephadex LH-20 gel filtration, normal phase and reversed-phase (RP) column, preparative thin-layer and high pressure liquid chromatography (HPLC). Silica gel chromatography was employed only if bioactive compounds were found to be stable under these mildly acidic conditions. 

Bioassay-guided fractionation of the bioactive alcoholic extracts of V. Candida involving solvent-solvent partition, Sephadex LH-20 gel filtration. Si gel column chromatography and reversed-phase HPLC as appropriate afforded a novel moderately bioactive 6,7-seco-rosane diterpenoid, candidalactone (31) [35]. The gross structure of candidalactone (31), including relative stereochemistry, was determined by the application of H-, C-NMR, DEPT, COSY-45, HETCOR and NOESY spectroscopy. Another new but inactive diterpenoid, candidenoidiol, was also isolated and its structure was elucidated as 10S,11R-dihydroxy-5(6),15-rosanedien-7-one (32) with the help of H-, C-NMR, dept, COSY-45, HETCOR, HMBC and ORD spectroscopic techniques. 

In contrast to HPLC, where polar effects dominate molecule separation, gel permeation chromatography (GPC) separates molecules according to their molecular size. Types of stationary phase and eluents used for GPC are HIBAR columns (Merck) [33] and Microgel (Chrompack) columns [215] of different pore size with tetrahydrofurane as eluent [33,214,215] Sephadex LH 20 gel and a sodium acetate solution [216] orN,N-dimethylformamide [217] as mobile phase Styragel columns and dimethylformamide eluent containing 2% acetic acid [218] and micro-packed, fiised-silica columns with tetiahydrofiirane as eluent [219]. Detection is by ultraviolet absorbance at the same wavelength discussed in HPLC analysis. 

Sephadex LH-20 gel column with isopropanol followed by acetone. About 90% of the basic mutagenic activity is recovered in the acetone subfraction, which comprises approximately 0.5 wt% of the crude oil. Development of this separation scheme (Figure 5) was made possible by use of microbial mutagenesis assays as the detector during exploratory liquid chromatographic separations. Table 7 lists some of the preliminary data from these studies. 

Load the sample solution onto the Sephadex LH-20 gel bead surface carefully. 

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