Extraction methods, viii

Rapeseed. Methods employed in processing of rapeseed protein products influence emulsion capacities (48, 49). Kodagoda et al. (48) showed that rapeseed protein isolates from water extracts emulsified more oil than isolates from acid or alkali extracts (Table VIII). Rapeseed isolates emulsified more oil than their concentrate counterparts. Rapeseed isolates and concentrates from acid extracts were far superior in emulsion stability to rapeseed protein products from water or alkali extracts. 

All MS technologies require the establishment of method-specific mass libraries so that compounds in the spectra can be identified [212], a tedious task that has been restricted to large laboratories. Nevertheless, some of these efforts are driven by the metabolomics community, thereby requiring some sort of standardization to conduct comparable experiments, as has been proposed with the ArMet standard [216], Last but not the least, metabolomics experiments generate large amounts of data that need sophisticated analysis methods to extract biological information, usually based on multidimensional statistics [3, 5, 58, 209, 217, 218]. Metabolomics experiments as the basis for an analysis of the possible dynamics of metabolic networks are discussed in Section VIII. 

Os(VIII) reacts with thiopyrine to form [0s(0)2(CnHi2N2S)2]-(CI04)2, which is used as a method of extraction into CHC13 for the spectrophotometric determination of Os(VIII) (473). 

The density stepping method was then run on a spiked soil sample. Five grams of soil were spiked with the same solution of herbicide standards used to spike the celite sample and the solvent was allowed to evaporate. The spiked sample was then placed into an extraction thimble and extracted. The results were different than those obtained from the spiked celite. Even at a high density of C02 the herbicides were not extracted. Previous experience showed that using water as a modifier aided in the extraction of diuron from soils (6)(7). Therefore 1 ml. of water was added to the spiked soil and the sample rerun at a density of 0.9 g/ml of C02. The results showed a significant increase in recovery of the herbicides with the addition of water. This demonstrates that the addition of a modifier added to the extraction cell can have a significant effect upon the extraction recoveries (8)(9). The results are summarized in Table VIII. 

TABLE VIII. Conversions for Extraction of Morwell Coal (15 g dry) in a Rocking Autoclave (Method B) with Aqueous Solvents (150 g) at... 

Results from the reverse phase HPLC study suggested that since a preliminary extraction of plasma with petroleum ether was required to remove lipids, that a 1 ml sample of plasma could be extracted first at a neutral pH to remove I followed by acidification to pH 4 and extraction to remove VI. Indeed this was found to be practical. Thus to 1 ml of plasma could be added either d3 I or VIII, depending upon which assay method was to be used, as internal standard followed by extraction with petroleum ether. To the plasma would then be added 1 ml of pH 4 buffer and benzylbiphenyl followed by extraction with benzene-isopropanol. 

This method, used for air and biological samples (13) Is subject to Interferences from other divalent metals readily chelated by dithizone. Addition of other complexing agents, double extractions, and pH control have been used to eliminate metal Interferences (Table VIII). 

The ability of certain soils to sorb the chemical strongly is important in analyzing residues of the chemical in soil. A procedure must be developed which will recover the chemical quantitatively from any soil. Table VII compares extraction from two soils, soil 3 which saturates with 4-amino-3,5,6-trichloropicolinic acid quickly and soil Bi which shows the slow takeup phenomenon. It is apparent that soil Bi, incubated 2 hours, holds the chemical more firmly than soil 3, incubated 5 days, but that hot water will remove most of the chemical from both soils. When soil Bi has been incubated for 28 days, removal of chemical was only 78.7% after three water washes, but further extraction with NaOH increased the recovery to over 99%. Several mild methods of extraction are compared in Table VIII. The same experimental techniques were used here but, instead of determining the extracted 4-amino-3,5,6-trichloropicolinic acid, the washed soil was assayed. A 50-mg. portion of dried, ground soil was suspended in a silica gel medium for scintillation counting and... 

The results of calculations for the two separation methods are summarized in Table VIII. Fewer trays are required in the azeotropic distillation column than the extractive distillation column. The heat loads are also smaller. The quality of the ethanol product is also slightly better for the azeotropic distillation method. Including the stripper for processing the aqueous phase, the total heat load for reboilers for the azeotropic distillation method is less than half that for the extractive distillation method. The total condenser load is roughly two-thirds that for the extractive distillation method. 

The contribution of the variance of the atomic absorption analysis to the total variance was calculated from duplicate AA analyses of the same extract, usually at the beginning and end of a series of AA measurements of a single metal. The variance of the AA method and the variance of all other factors, including the extraction itself, were calculated and are presented in Table VIII. It can be observed that the contribution to the total variance by the AA measurement is substantial for Cd, Ni, Pb, and Zn. The relative standard deviation from other sources, including the extraction technique itself, contamination, and variation between sup-... 

Koekemoer MJ, Warren FL. The senecio alkaloids. VIII. The occurrence and preparation of the N-oxides. An improved method of extraction of the senecio alkaloids. J Chem Soc 1951 47 66-8. 

Five inositolphosphosphingolipids (compounds II, m, V, VI and VIII) have been isolated, purified and analyzed from the yeast phase of H. capsulation [61], a dimorphic fungus that causes histoplasmosis. Cells uniformly labeled with [3H] inositol and [32P] were treated with 5% TCA at 0°C and extracted according to Hanson and Lester s method [62]. Isolated lipids were purified by preparative liquid chromatography (HPLC) on silica gel columns and utilized for structural analysis. 

The method of preference for methyl mercury determination has involved determination of methyl mercury halides by gas chromatography after certain preconcentration extractions (1,5,23,28). However, we have discovered that by the removal of the potassium persulfate reagent and the reduction of the digestion temperature to 800 in the standard method (10), it can be used for obtaining an estimate of the methyl mercury species in water. An evaluation of this method compared to results using the GC method is illustrated in Table VIII. Clearly the GC method is more selective but the FAA method appears to give a reasonable, though lower concentration for methyl mercury in water. 

Ir(IV), Rh(III), Pt(IV), Os(VIII), Pd(II), and Au(III) were sorbed from aqueous solution by silica gel, which was chemically modified with nitrogen-containing organic ligands. This was performed as a function of hydrochloric acid concentration, time of contact, concentration of the element, and the ionic strength. Extraction, followed by determination on the sorbent surface by x-ray fluorescence of Ir(IV), and Rh(III), from 10 to 10 M solutions, were achieved. An atomic emission method was used to determine Au(III) on the surface of the sorbent containing bonded diethy-lenetriamine groups. 

A number of zoopolysaccharides have been isolated in purified condition and the structures partially established. Many of these are bound with other tissue components in the natural condition. They are isolated from the macerated tissues or the secretions by extraction with alkalies or salts (especially calcium chloride). Mucins and many mucoids are precipitated by weak acids, and their polysaccharide components are subsequently recovered. If dissociable, proteins may be removed by precipitation with amyl alcohol - chloroform (Sevag) or formaldehyde (Masamime). Peptic or tryptic digestion may remove these and covalently bound proteins. Colorimetric, chromatographic, and isolation methods have been used for the identification of the component sugars (, 14, 15-16h), (See also imder Glucosamine, Chapter VIII, Uronic acids. Chapter VI and part I, Chapter XII.)... 

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