Extraction plant waxe

Standley, L. J., and B. R. T. Simoneit, Characterization of Extractable Plant Wax, Resin, and Thermally Matured Components in Smoke Particles from Prescribed Burns, Environ. Sci. Technoi, 21, 163-169 (1987). 

DDT converts in part to p,p -DDE over time in the environment, especially in sediments [151, 171]. An example of the total aliphatic extract of a sediment from the Los Angeles Bight contaminated with p,p -DDE is shown in Fig. 11. The TIC trace shows a major UCM and the minor resolved peaks are normal alkanes (primarily from higher plant wax), with mature 17a(H),21/ (H)-hopanes (from petroleum residues as is the UCM). The mass spectrum ofp,p -DDE is shown in Fig. 12a, registering the molecular ion cluster at m/z 316-320. DDE is detected in the m/z 246 fragmentogram (Fig. lid), appearing as a small peak in the TIC trace and DDT is not detectable in this sample. 

The residue obtained is repeatedly washed with fresh amounts of the same solvent to maximize yield. Solvent is then recovered in a still at reduced pressure, which lowers the solvent s boiling point and permits the use of gentle heat. The concentrated extract is not distilled but is retained in the vessel in a liquid state. When it is removed and cooled, the concentrated extract solidifies to a waxy consistency called a concrete, which is made up of approximately 50% odourless wax. The unwanted wax is removed by washing with alcohol, which extracts the essential oil. The alcohol mixture is then filtered and alcohol is removed by vacuum distillation. The final residue is called the absolute. A typical solvent extraction plant is shown in Fig. 4.4 in this system the solvent is pumped through a bed of the plant material. 

Cleanup A practical term used to describe the handling of a sample before the measuring step. For example, after the pesticides are extracted from a vegetable, the extract may contain fats and plant waxes that will interfere with the determination of the pesticides. These fats and waxes are removed by solid phase extraction, column chromatography, or gel permeation chromatography, and the extract then is said to be cleaned up,... 

One suggestion is to back extract with supercritical carbon dioxide, which is also a clean solvent. Another alternative is to do the reverse, i.e. extract the plant material first with carbon dioxide to obtain a concrete or oleoresin , which contains heavy materials, such as plant waxes. The concrete can then be treated with superheated water, as described below in the section on liquids. However, the use of supercritical carbon dioxide is probably not economically viable for most products. 

These fatty alcohol esters of fatty acids are only minor constituents of most woods. However, for a time, wax was prepared by solvent extraction of Pseudo-tsuga menziesii bark. The extraction plant that operated for six years by Bohemia, Inc., Eugene, Oregon, closed in 1982 for economic reasons. The plant produced a single grade of wax that competed with imported waxes. Besides the above ester, the crude wax contains an interesting mixture of estolides of hydroxy fatty acids, and fatty alcohol esters of caffeic and ferulic acids. 

The next step in sample preparation is to pirrify the crude extract. Plant extracts contain much ballast material, both nonpolar (chlorophylls and waxes) and polar, such as tannins or sugars. Most often liquid-liquid extrac-ti(Mi is used, which takes advantage of solubility differences of hydrophobic substances, which have affinity for nonpolar solvents, and hydrophilic substances, which have an affinity for aqueous solutions. 

Absolute. This is concentrated extract obtained by treatment of a concrete or other hydrocarbon-type extract of a plant or plant part with ethanol. It is usually Hquid and should be totally soluble in alcohol. By this method, waxes, hydrocarbons (including terpenoid), as well as most of the odorless material of the concrete are removed from the extract. 

Scraped-surface exchangers are particularly suitable for heat transfer with crystalhzation, heat transfer with severe folding of surfaces, heat transfer with solvent extraction, and heat transfer of high-viscosity fluids. They are extensively used in paraffin-wax plants and in petrochemical plants for ciystallization. 

Traditionally, dried or powdered plant material is used and extracts can be obtained by mixing the material with food-grade solvents like dichloromethane or acetone followed by washing, concentration, and solvent removal. The result is an oily product that may contain variable amounts of pheophytins and other chlorophyll degradation compounds usually accompanied by lipid-soluble substances like carotenoids (mainly lutein), carotenes, fats, waxes, and phospholipids, depending on the raw material and extraction techniques employed. This product is usually marketed as pheophytin after standardization with vegetable oils. 

Lipid-soluble food grade copper chlorophyll is manufactured similarly by extraction of adequate plant material, followed by replacement of magnesium by copper, and purihcation steps to remove carotenoids, waxes, sterols, oils, and other minor components that are co-extracted. Commercial copper chlorophylls may vary physically, ranging from viscous resins to fluid dilutions in edible oils as well as granulated forms and emulsions standardized with edible vegetable oil. Colors may vary... 

Grade extracts of different plants are often rich in lipophilic substances, such as plant oils, chlorophylls, and waxes and also highly polar components such as tannines or sugars. Because the complicated liquid-liquid extraction (LLE) procedures are... 

In a sensitive and specific colorimetric method 1,1,1-trichloro-2,2-bis(p-methoxyphenyl)-ethane is extracted from plant or animal tissue, using benzene or petroleum ether as the solvent. The solvent is evaporated at room temperature by a current of air and the residue dehydroha log ena ted with 2% alcoholic potassium hydroxide. By petroleum ether extraction the resulting 1,1-dichloro-2,2-bis(p-methoxyphenyl)-ethylene is removed from the reaction mixture. After the solvent is removed by air evaporation the dehydroha log ena ted methoxychlor is isolated from the nonsaponifiable portion of the fats and waxes by dissolving the residue in hot acetone, chilling, and filtering. After the acetone is removed by air evaporation, the residue is treated with 85% sulfuric acid. This produces a red solution with an absorption maximum at 555 m/z, the intensity of which can be read on a colorimeter and is a function of the methoxychlor concentration. Beer s law is obeyed over the range of 1 to 50 micrograms. 

Other waxes have not been studied to the same extent as beeswax. They derive from a variety of plant, animal and also mineral sources, as described in Chapter 1, where more detailed information on their chemical composition is reported. HTGC/MS analysis after solvent extraction has been successfully used to identify spermaceti, candellila and Japan waxes which have been used in the manufacture of works of art [37]. In particular, in the case of spermaceti wax it has been possible to understand the structure of the various isomers of even-numbered esters ranging from C26 to C34, as well as odd-numbered esters detected in low amounts. The mass spectra obtained demonstrated for the first time that spermaceti esters are mainly composed of hexade-canol and octadecanol moieties associated with a range of FAs containing 10 20 carbon atoms. 

On the other hand, gas chromatographic methods may overestimate the concentration of total petroleum hydrocarbons in a sample due to the detection of nonpetroleum compounds. In addition, cleanup steps do not separate petroleum hydrocarbons perfectly from biogenic material such as plant oils and waxes, which are sometimes extracted from vegetation-rich soil. Silica gel cleanup may help to remove this interference but may also remove some polar hydrocarbons. 

---