Solid-liquid extraction system

Lee, Y.N. and Wiley, R.C., Betalaine yield from a continuous solid-liquid extraction system as influenced by raw product, post-harvest and processing variables, J. Food ScL, 46, 421, 1981. 

Fig- 4.20 (A) Combined griding and solid-liquid extraction system for solid samples. (B) Subsequent phase separation by high-speed centrifugation. (Reproduced from [17] with permission of Francis Taylor Ltd.). 

Fig. 4.21 Automated discrete solid-liquid extraction system for determination of mineral nitrogen in soils. (Reproduced from [18] with permission of the Royal Society of Chemistry).

Figure 32 Comparison of germanium extraction with Kelex 100 in liquid-liquid and solid-liquid extraction systems. (From Ref. 30.)...

Gonzales, M., Gallego, M., and Valcarcel, M., Liquid chromatographic determination of natural and synthetic colorants in lyophilized foods using an automatic solid-phase extraction system, J. Agric. Food Chem., 51, 2121, 2003. 

The most common (off-line) sample preparation procedures after protein precipitation are solid phase extraction and liquid-liquid extraction. Multiple vendors and available chemistries utilize 96-well plates for solid phase extraction systems and liquid-liquid extraction procedures. Both extraction process can prepare samples for HPLC/MS/MS assay. Jemal et al.110 compared liquid-liquid extraction in a 96-well plate to semi-automated solid phase extraction in a 96-well plate for a carboxylic acid containing analyte in a human plasma matrix and reported that both clean-up procedures worked well. Yang et al.111 112 described two validated methods for compounds in plasma using semi-automated 96-well plate solid phase extraction procedures. Zimmer et al.113 compared solid phase extraction and liquid-liquid extraction to a turbulent flow chromatography clean-up for two test compounds in plasma all three clean-up approaches led to HPLC/MS/MS assays that met GLP requirements. 

McLoughlin, D.A., Olah, T.V., and Gilbert, J.D. 1997. A direct technique for the simultaneous determination of 10 drug candidates in plasma by liquid chromatography/atmospheric pressure chemical ionization mass spectrometry interfaced to a Prospekt solid-phase extraction system. J. Pharm. Biomed. Anal. 15 1893. 

Sonication helps improve solid-liquid extractions. Usually a finely ground sample is covered with solvent and placed in an ultrasonic bath. The ultrasonic action facilitates dissolution, and the heating aids the extraction. There are many EPA methods for solids such as soils and sludges that use sonication for extraction. The type of solvent used is determined by the nature of the analytes. This technique is still in widespread use because of its simplicity and good extraction efficiency. For example, in research to determine the amount of pesticide in air after application to rice paddy systems, air samples collected on PUF were extracted by sonication, using acetone as the solvent. The extraction recoveries were between 92% and 103% [21]. 

The selection of solvents for LLPC is similar to the selection of solvents in liquid-liquid extraction systems. The solid support has little effect upon the selection of the solvent pair, except for the obvious fact that a hydrophilic support for a polar stationary phase requires a hydrophobic... 

The other area is the countercurrent liquid-liquid extraction system, shown in Fig. 27, using mixer stages separated by stationary horizontal discs. These have the advantage of only one interface for settling to occur, plus the fact that solids can be handled in one or both phases. Also, all the principals of fluid mixing can be used to design an effective transfer system. The design procedure is also based on the KLa concept, discussed in Section IV, and allows the calculation of reliable full-scale performance, based on pilot plant work, often done in a laboratory column about 6 in. in diameter. 

Systems have been developed that allow the recycling of catalysts. The first case study involved simple adsorption of proline onto silica gel [6], but the system suffered from a loss in enantioselectivity. More recently, promising results have been obtained with fluorous proline derivatives [64] used for aldol reactions the recycling of fluorous catalysts has been demonstrated using fluorous solid-liquid extraction. Solid phase-supported catalysts through covalent bonds [65] and through noncovalent interactions [66] were also used for aldol reactions. Proline and other catalysts can be recycled when ionic liquids or polyethylene glycol (PEG) were used as reaction solvents [67]. 

PURIFICATION OF SOLUTION-PHASE LIBRARY INTERMEDIATES AND FINAL COMPOUNDS LIQUID-LIQUID AND SOLID-PHASE EXTRACTION SYSTEMS... 

Algebraic Computation This method starts with calculation of the quantities and compositions of all the terminal streams, using a convenient quantity of one of the streams as the basis of calculation. Material balance and stream compositions are then computed for a terminal ideal stage at either end of an extraction battery (i.e., at Point A or Point B in Fig. 18-81), using equilibrium and solution-retention data. Calculations are repeated for each successive ideal stage from one end of the system to the other until an ideal stage which corresponds to the desired conditions is obtained. Any solid-liquid extraction problem can be solved by this method. 

For varying requirements, the following systems have proved to be efficient Solid/liquid-extraction... 

One example of a separation cascade is the liquid/liquid extraction system where the desired isotopic enrichment takes place in phase A. Using systems with crown ethers or cryptands, these ligands should have a good solubility in one phase, whereas the same compounds should be insoluble or difficult to dissolve in the other phase. This also applies to chemical reactions in solid/liquid systems, e.g. in the system ion... 

Automated On-Line Solid-Phase Extraction System, J. Liquid Chrom. Rel. 

Eiquid- or solid-phase extraction methods have been adopted for the isolation of catecholamines and their metabolites from urine samples. The liquid extraction system is ordinarily based on the formation of a complex, in alkaline medium, between diphenylborate and the diol group in the catecholamines. However, the liquid extraction methods reported in the literature are relatively tedious and often involved multiple extraction steps.For the more widely used solid-phase extraction methods, catecholamines may be selectively isolated from the urine sample by adsorption with activated alumina," " phenylboronic acid or cation-exchange resins. All the specimen preparative procedures are specific for the free catecholamines, i.e. the extracted catecholamines do not include the conjugated fraction. 

Systems requiring only partial dissolution of the sample call for llxlvia-tlon rather than dissolution or digestion. Such systems are dealt with in Section 4.9, devoted to solid-liquid extraction. 

Figure 4.23 Illustrates another alternative for the separation of both phases once the batch liquid-liquid extraction has been finished. Formerly conceived for solid-liquid extractions, this complex mechanical assembly [20] consists of two automatic burettes for addition of the two phases, the extractor —moveable in various fashions— and a vertically moving paddie stirrer. The extraction vessel rotates at a high speed, which promotes phase separation, as shown in the figure. The lighter phase creeps up the walls and passes to an upper receptacle —the separation is facilitated by adding more aqueous phase. Once separation Is complete, an aspiration probe withdraws the organic phase. Finally, a mechanical system turns the vessel over for cleaning.

The automation of the use of disposable cartridges for solid-liquid extraction connected directly with a liquid chromatograph poses major techical problems which are, however, lessened by robotics. Although several partly automatic systems have been described [23-26], there is only one really completely automated system, which was reported recently [27]. It is an automated cartridge exchange module combined with a low-cost purge pump, a solvent selec-... 

The automation of sample collection and treatment in gas chromatography has had a less extensive development than in HPLC. Some of the systems described above can be used in GC by introducing slight modifications if liquid samples are to be used. Thus, a continuous unsegmented liquid-liquid extraction system was recently developed for the determination of water pollutants [2B]. Below are discussed two commercial systems as examples of automation prior to introduction of the sample into a gas chromatograph in dealing with two analytical problems control of environmental pollution and analysis for volatile compounds in solid or semi-solid samples. 

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