Bulk extraction

Materials. Aldicarb standards were obtained from the United States Environmental Protection Agency (USEPA), Quality Assurance Section and from Union Carbide Corporation. Crystalline samples of carbofuran and 3-hydroxycarbofuran were supplied by the Agricultural Chemical Group of FMC Corporation. Reference standards of methomyl (99% pure) and oxamyl (99% pure) were obtained from USEPA. HPLC grade methanol was purchased from Burdick and Jackson, Inc. Methylene chloride used for bulk extractions of the carbamate pesticides in solution was recovered, distilled and reused. Analytical reagent grade chemicals and solvents were used in all experiments. Doubly distilled deionized water was used for solution rate studies. Deionized distilled water (DDW) was used for dilutions in reactive ion exchange experim ts., , ... 

Sample collection. Various plant parts (bark, leaves, roots, and twigs) of II. llttoralls were collected (16) from the Mangrove Forest Reserve in Pagbllao, Quezon in the Philippines. The plant materials were chopped into smaller pieces before extraction. A re-collection of 21 kg of air-dried ground roots was made for bulk extraction. 

The widespread distribution of natural products on land Views on the distribution of secondary metabolites are changing. Once thought to be strictly taxon-specific, the same families of secondary metabolites, if not just the same compounds, are more and more frequently encountered in taxonomically, phylogenetically, and ecologically distant organisms (Chapter 3). It is the advancement in analytical technology that allows us to detect compounds that have escaped attention in the past, hidden in the bulk extracts or present in trace amounts. 

The bulk extraction of hemicelluloses and pentosans from woody biomass and their conversion to furan compounds. 

At equilibrium, the concentration of the extract within the marc is the same as the concentration of the bulk extract. Also, defining X as the weight fraction of solvent in the marc, Equation 11.6 can be simplified to the the following ... 

The rest of this section will present details about various aspects of the process getting the extraction solvent from a gas cylinder to the extraction chamber, controlling the extraction conditions, separating the extracted components from the supercritical extraction fluid, and collecting and reconstituting extracted components. Note that the discussion will focus on using carbon dioxide as the primary, bulk extraction fluid since this is the most widespread fluid in use for analytical-scale SFE at this time. 

Unlike the SMB, where a 6 C fatty acid anomaly was noted, the fatty acid fraction in the Antarctic sediments exhibits a value comparable to other fractions, but lower than the bulk extracted sediment and within the range of Cje and Cjg fatty acids characteristic of marine origin (UcHiDA et al., 2001). This conclusion is also consistent with the carbon number distribution of alkanes, alkenes, fatty acids, alcohols and sterols which reflects the predominance of marine-derived carbon with little recognizable higher plant debris in the sediment. Similar molecular distribution of the lipid classes has previously been reported in sediments from the same general locations in the McMurdo Sound (Venkatesan, 1988). 

One property of SPME that distinguishes it from other types of extraction is the phase ratio (organic or extracting phase volume/sample volume). The phase ratio in SPME can be very small (e.g., 1/1000). When the phase ratio is small, then the number of moles of an analyte extracted can be small in comparison to the total number of moles in the sample. Unlike in bulk extraction where most of the analyte can be extracted from a sample, in SPME it is possible that a negligible fraction of the analyte in a sample is extracted. Because of this, the quantity extracted will reflect the free... 

Finally, there are some secondary considerations in SPME that, if properly handled, can improve analysis. SPME probes are reusable, which is great from a cost and environmental burden perspective, but as a consequence carryover is a concern. Washing (or heating for volatile solutes) is essential between applications. Modifying the sample, for example, by adding salt, can influence analyte yield. Unlike in SPE or bulk extraction, it is not necessary to choose between a polar and a nonpolar phase. Phases with both properties, e.g., Carboxen/PDMS exists. Carboxen is a porous carbon that adsorbs polar and nonpolar solutes, and PDMS is quite nonpolar. 

Bulk Extraction of Anacardic Acids for NMR. Separate batches (2.5Kg each) of resistant and susceptible inflorescences were soaked in methylene chloride for one hour. The methylene chloride extracts were dried, filtered and evaporated as described above to leave crude resistant and susceptible exudates. A preliminary clean up of each was performed using column chromatography. Each crude extract was dissolved in hexane (15mL) and 5mL of that was applied to a silica gel chromatography column (18cm x 2cm) and eluted successively with (i) hexane (lOOmL), (ii) 4% diethyl ether, 1% acetic acid in... 

Identification of the respective peaks was accomplished by adding samples of [ H]-labeled peaks to a bulk extract of seed coats and cotyledons. The extract was purified through three sequential HPLC purification steps based on the occurrence of labeled material. The purified peaks, methylated before the last HPLC step, were acetylated as necessary for GC>MS (Carlo Erba/Kratos M-25). Methyl-PA, methyl-DPA and acetylated-methyl DPA-G were identified by their total ion scan mass spectra. 

In some flow sheets, a scrub circuit is introduced between the extraction and stripping circuits. A scrub liquor is introduced to scrub off unwanted coextracted species from the loaded organic phase by displacing the impurities with the more strongly complexed main element. This produces a scrubbed organic phase. For systems in which the extractant is completely selective for the species of interest or when high selectivity of extraction is not required (such as for bulk extractions), a scrub circuit is not necessary. Usually, however, some coextraction of other species occurs and a scrub circuit is anployed to reduce the transfer of these species to the LSL. 

Seidel V (2012) Initial and bulk extraction of natural products isolation. Methods Mol Biol 864 (Copyright (C) 2012 U.S. National Library of Medicine.) 27-41... 

If step (3) is rate determining, the process presumably reduces to a typical extractant film limited mass transfer, the rate for a given solvent velocity being approximately proportional to the product of the effective area for mass transfer of the solute from the solid matrix into the solvent and C - C. C is the concentration of solute in the bulk extractant and C is the equilibrium concentration. 

We have reviewed literature and experimental results which demonstrate that the plant cell wall is a greater obstacle to plant enzyme isolation than has been appreciated. We have also discussed the use of cryogenic techniques in combatting both secondary metabolites and cell walls, and described a convenient liquid-N2 homogenizer for bulk extraction of plant tissues. In addition we have pointed out that plant phenolics are not the only secondary products that cause problems in plant enzymology. 

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