Plant extracts selectivity systems

Over the last two decades there has been a resurgence of interest in the study and use of medicinal plants. The WHO (World Health Organization) has confirmed the importance of traditional medicine to a majority of the. world s population and encourages all countries to preserve and to use the safe and positive elements of traditional medicine in their national health systems. The WHO Traditional Medicine Programme (1) was inspired by the observation that 80% of the world s population treats diseases exclusively with traditional medicines, and most traditional therapies involve the use of plant extracts or their active constituents. Vegetable species from South America and China are of particular interest in view of their wide use in traditional medicine they offer local populations immediately accessible safe and effective therapeutic products. However only a small fraction of South American and Chinese medicinal plants have been studied. Therefore it is of general interest to document the experience of traditional healers, to select interesting medicinal species and to identify the constituents responsible for their therapeutic or toxic effects. 

All solutes were thus enzymatically and chemically leveled to OT which was selectively detected in base at a Ag working electrode in a system similar to Fig. 60D. S ium hydroxide (2 M) was mixed after the enzymatic column to refease CN per Eq. (30). The enzyme reactors were found to be quite rugged over a period of several months before deactivation mobile phases typically contained I S% methanol in pH 7 phosphate buffer. The system was applied to the identification of cyanogenic glycosides and cyanohydrins in crude plant extracts. The selectivity of electrochemistry over UV-visible absorbance is quite apparent in Fig. 62, where using the crude extract was sufficient. Several cyanogenic constituents could be cleanly resolved and detected electrochemically even after massive dilutions with mobile phase. 

There are many examples of the studies on SLM for nuclear applications in the literature. SLMs were tested for high-level radioactive waste treatment combined with removal of actinides and other fission products from the effluents from nuclear fuel reprocessing plants. The recovery of the species, such as uranium, plutonium, thorium, americium, cerium, europium, strontium, and cesium, was investigated in vari-ons extracting-stripping systems. Selective permeation... 

A gas processing plant selectively extracts ethylene and ethane from an incoming natural gas mixture stream. These two light hydrocarbons are absorbed in a heavy gasoline type absorber oil, and then stripped with open steam in an open tower. The system data are (see Figure 8-41) ... 

Analysis of methyl parathion in sediments, soils, foods, and plant and animal tissues poses problems with extraction from the sample matrix, cleanup of samples, and selective detection. Sediments and soils have been analyzed primarily by GC/ECD or GC/FPD. Food, plant, and animal tissues have been analyzed primarily by GC/thermionic detector or GC/FPD, the recommended methods of the Association of Official Analytical Chemists (AOAC). Various extraction and cleanup methods (AOAC 1984 Belisle and Swineford 1988 Capriel et al. 1986 Kadoum 1968) and separation and detection techniques (Alak and Vo-Dinh 1987 Betowski and Jones 1988 Clark et al. 1985 Gillespie and Walters 1986 Koen and Huber 1970 Stan 1989 Stan and Mrowetz 1983 Udaya and Nanda 1981) have been used in an attempt to simplify sample preparation and improve sensitivity, reliability, and selectivity. A detection limit in the low-ppb range and recoveries of 100% were achieved in soil and plant and animal tissue by Kadoum (1968). GC/ECD analysis following extraction, cleanup, and partitioning with a hexane-acetonitrile system was used. 

Just like all herbal medicinal preparations, C. sativa should be standardized if extracts or whole plant material are to be used for medicinal purposes. Basic requirements are that all detectable constituents should be known, but also a sustainable quahty control system must be established to achieve the same quahty over all batches. For industrial use of cannabis, standardization could also be necessary to equahze the quality of the product. However, it must be stated that cultivation for this purposes is mostly performed outdoors. Outdoor growth makes standardization of the product difficult due to the environmental changes. For this reason the Dutch medicinal C. sativa is grown under strictly controllable conditions, and therefore indoors, by the company Bedrocan. At this company clones are used for breeding to maintain high standards for quantity and quality. After a strictly selective breeding procedure a plant fine has been estabhshed fulfilhng all criteria as a herb for medicinal use. 

The polymer/additive system in combination with the proposed extraction technique determines the preferred solvent. In ASE the solvent must swell but not dissolve the polymer, whereas MAE requires a high dielectric solvent or solvent component. This makes solvent selection for MAE more problematical than for ASE . Therefore, MAE may be the preferred method for a plant laboratory analysing large numbers of similar samples (e.g. nonpolar or polar additives in polyolefins [210]). At variance to ASE , in MAE dissolution of the polymer will not block any transfer lines. Complete dissolution of the sample leads to rapid extractions, the polymer precipitating when the solvent cools. However, partial dissolution and softening of the polymer will result in agglomeration of particles and a reduction in extraction rate. 

---