Extraction conditions and

FIGURE 8 HPLC chromatogram of a tablet extract of an OTC product from natural material showing many natural components including active ingredient (peaks labeled A ), preservatives P and degradants D . Note that Peak A2 was found to hydrolyzed into D under neutral extraction conditions and component D was found to be retained by Nylon filters. 

Barnes, S., Kirk, M., and Coward, L., Isoflavones and their conjugates in soy foods extraction conditions and analysis by HPLC-mass spectrometry, J. Agric. Food Chem., 42, 2466, 1994. 

PenicUlin-G Amberlite LA-2 and dioctylamine Na2C03 Co-trans- ELM port of H+ ELM Simple model of permeation rate accoimting for product decomposition Optimum extraction condition and procedure for determining the internal reagent worked out. DOA is a better carrier [50,53,54, 100]... 

Human erythrocytes, peripheral leukocytes and liver have been satisfactorily analyzed, but it should be recognized that each different tissue source may require different extraction conditions and modified solvent gradient elution in order to obtain maximal recoveries and optimal chromatographic resolution of the tissue characteristic glycosphingolipids. Fletcher,... 

Previous studies indicated that triazines in soils require rigorous extraction conditions and a need for water in the extraction solvent. Mattson et al (1970) found that minimally a 1-h reflux was required for extraction of weathered atrazine residues. Huang and Pignatello (1990) concluded that shaking samples for 2 1 h in hot (95°C) solvent was required to achieve extraction of atrazine residues, whereas shaking at room temperature yielded about 40% fewer residues. Increasing unheated shaking time to 24h realized only minor improvement. 

The time dependence of the extraction process is showed in figure 4. Under constant extraction conditions of 350 bar and 80 °C an extraction period of 10 minutes yielded to a recovery rate of < 2 %. This means that the extractor needed about 10 min for getting the desired extraction conditions and the extraction process started. After 30 min about 62 % of the used amounts of TBBA were extracted. Increasing the extraction time by a factor of four yielded to a recovery of 80 %. As expected from the theory longer extraction times yielded only to slightly hiher extraction efficiencies. To make the extraction process more effective it would be better to rise e g. the extraction pressure... 

Table I. Extraction Conditions and Properties of Tannin Extracts...

Several catalyst regeneration experiments were conducted with pyridine as the solvent using different extraction conditions and the catalyst activities were measured. The conditions of catalyst extractions are listed in Table II and the stabilized activities of the catalysts after 5-6 h of activity tests are shown in Figures 2 and 3. The catalyst characteristics were examined only in one run, which are shown in Table III. 

It should be recognized that the coated tubes were subjected to a severe extraction condition. And so, due to the mechanical flexing and to the tensile stress resulted from the swelling of the silicone tubing during the extraction, the surface of the plasma polymer coating was stained by the oil-soluble dye after the extraction. 

Shirey, R.E., Optimization of extraction conditions and fibre selection for semivolatile analytes using solid-phase microextraction, J. Chromatogr. Sci., 38, 279-288 (2000)... 

In addition to the harsh extraction conditions, not all citrus waste is amenable to conventional pectin extraction. Mandarin orange peel becomes jelly-like on heating and separation of pectin from the residue is difficult (27). Milder extraction conditions and more effective extraction has been reported if mandarin citrus peel was suspended in water with Trichosporon pencillatum for 15 to... 

An example described in the patent relates the extraction conditions and the flow rates employed for a test The flow rates reported are huge. The patent reports that coffee liquor containing 15% solids is fed at 11,000 Ib/hr to the evaporator and concentrated to 30% solids 4,950 Ibs/hr of concentrate is fed to the extraction tower, and 5,500 Ibs/hr of condensate is sent to the top of the tower. CO2 at 40 °C and 300 atm and at a flow rate of 495,000 Ibs/hr ( ) is pumped to the bottom of the tower to strip caffeine from the coffee liquor passing downward through the tower. 

The total content of neutral sugars varies with the source, the extraction conditions, and subsequent treatments,... 

While the consideration of parameters such as flow, temperature, density, time, and modifiers may be fairly straightforward, perhaps the least predictable factor is that of matrix effects. The matrix either has the analyte lying on its surface (adsorbed), or the analyte is entrained in the matrix (absorbed). In the case of adsorption, the extraction can be accomplished with milder conditions. If the analyte is absorbed into the matrix, stronger extraction conditions and longer extraction times may be necessary. The matrix also carries its own modifiers in the form of water, and/or fats, and/or oils. If the desired analyte is of a polar nature, the water content of the matrix will facilitate the extraction. If the desired analyte is nonpolar, the water will inhibit the extraction. The opposite effects are evident with oils/fats in the matrix. If significant variations of the matrix are expected, an extraction scheme must be developed with these extremes in mind. (The importance of matrix effects is exemplified in the extraction of cyclosporine, as discussed below.)... 

Complex Mixture Extraction. Analytical SFE can also be used for complex mixture sample preparation. Typical examples using hazardous waste samples are described below. Sample A was a soil boring contaminated with coal gasification residuals and sample B was from a waste stream from a treatment facility. The major objective of these studies was to compare the extraction abilities (e.g., amount of material extracted) of three different fluid systems using approximately four-gram aliquots of the samples. The specific fluid systems, the extraction conditions, and the percentage of the total mass of material extracted from each sample are listed in Table II. 

An Exxon cat cracker bottom pitch was extracted with solvents of varying solubility parameter in order to evaluate the relationships which exist between extraction conditions and the characteristics of the extracted product. The precursor pitch possessed a carbon/ hydrogen ratio of 1.49 and a alculatedO, overall average solubility parameter of 10.48 reflux quinoline insolubles content of the pitch was 2.3% and the refluxing toluene insolubles were at a level of 20.3%. The pitch was not optically anisotropic. Upon heating in N2 to 530 C in a TGA, a coke yield of 37% was obtained. 

Pan, X., Kadla, J.F., Ehara, K., Gilkes, N., Saddler, J.N. Organosolv ethanol lignin from hybrid poplar as a radical scavenger Relationship between lignin structure, extraction conditions and antioxidant activity. J. Agric. Food Chem. 54, 5806-5813 (2006)... 

The optimised HS-SPME extraction conditions and other parameters finally selected for use in sample preparation prior to GC-MS analysis are given in Table 3. 

Source From Evaluation of extraction conditions and use of HPLC-MS for the simultaneous determination of acrylamide and its primary metabolite, A-acetyl-S-(2-carbamoylethyl)cysteine, in human urine, in J. Liq. Chromatogr. Relat. Technol. 

Dunford, N.T. and Temelli, F. (1997) Extraction conditions and moisture content of canola flakes as related to lipid composition of supercritical CO2 extracts, 7. Food Sci. 62, 155-159. 

The basis of the success of this new kind operation is twofold, viz the high selectivity of supercritical fluids by fine-tuning the extraction conditions and thereby the density, the interactions, polarity of the fluid etc., and secondly the high diffusivity of such small molecules, even in natural products like coffee beans or in coal. Furthermore, the extracted products often can easily be obtained from the fluid by a simple change in pressure and/or temperature. 

The extraction was carried out with CO2 as SFE-fluid. Extraction conditions and experimental results are reported in table I. 

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