Tailor-made extractant

The increased use of computer graphics for modeling molecular structures and chemical reactions has opened a path for the synthesis of tailor-made extractants. Thus the future promises new varieties of extractants with highly selective properties for the desired process. 

Masque N, Marce RM, Borrull F (2001) Molecularly imprinted polymers new tailor-made materials for selective solid-phase extraction. TrAC, Trends Anal Chem 20(9) 477 186... 

The discussion in Section 4.4.1.3 on transport mechanisms in SLM has manifestly demonstrated another facet of tuning analyte-selective extraction. For example, Figure 4.5 clearly demonstrates the selective extraction of a basic compound—all that is required here is a simple adjustment of the pH on either side of the membrane. Also, Figure 4.6 neatly illustrates the possibility of performing such selective extraction of anionic and cationic species in another transport mechanism that employs selective carriers. Thus, by fine-tuning the chemistry/composition of the sample, membrane liquid, and acceptor phases, analyte-selective extraction can be tailor-made. 

Molecular imprinting technique was recently used to prepare highly selective tailor-made synthetic affinity media used mainly in chromatographic resolution of racemates or artiftcial antibodies [130-133]. A complex between the template molecule and the functional monomer is first formed in solution by covalent or non-covalent interactions (Figure 3.10). Subsequently, the three-dimensional architecture of these complexes is confined by polymerization with a high concentration of cross-linker. The template molecules are then extracted from the polymer leaving behind complementary sites (both in shape and functionahty) to the imprinted molecules. These sites can further rebind other print molecules. 

To take away the mystery from the word supercritical, it should be recognized that a supercritical fluid can be used like any other solvent for maceration and percolation processes. The only restriction is that it must be handled under high pressure, a fact that requires a special and expensive design of the extraction apparatus. This obvious disadvantage however is compensated by many benefits as demonstrated below. Supercritical C02-extraction of botanical materials is today a well-developed and reliable procedure applied on an industrial scale for about 20 years. The equipment is available turn-key from various suppliers in multi-purpose design or tailor made for special applications. 

Edmundo, C., Valerie, D., Didier, C., and Alain, M., Efficient hpase-catalyzed production of tailor-made emulsifiers using solvent engineering coupled to extractive processing, J. Am. Oil Chem. Soc., 75, 309-313, 1998. 

Efficient separation of catalyst from the reaction medium can be achieved by extraction of polar rhodium complexes of TPPMS with water [8]. However, many catalytic processes for the production of fine chemicals require the use of modified tailor-made catalysts. The introduction of amphiphilic substituents on phosphines opens the way to easy separation of ligands that induce high selectivity and/or activity in catalytic reactions simply by extraction with acidic or basic water. 

An automated in-tube solid-phase microextraction HPLC method for NNK and several metabolites have been developed by Mullett et al. ° In-tube SPME is an on-line extraction technique where analytes are extracted and concentrated from the sample directly into a coated capillary by repeated draw-eject steps. A tailor-made polypyrrole-coated capillary was used to evaluate their extraction efficiencies for NNK and several metabolites in cell cultures. This automated extraction and analysis method simplified the determination of the tobacco-specific A-nitrosamines, requiring a total sample analysis time of only 30 min. 

Keywords Bacterial polymers, extraction methods, biosynthesis, tailor-made synthesis, applications... 

The goal of this chapter is to provide general information on various bacterial species and the kind of polymers obtained from them. We will also briefly discuss the conventional methods (extraction/isolation), biosynthesis, tailor-made synthesis, and applications of the bacterial polymers. 

Bacterial polymers obtained by any form (e.g. extraction, biosynthesis methods, tailor-made synthesis) are used for various industrial, agricultural, and biomedical applications [120]. The details of the applications are listed in Table 11.1. 

Currently cellulose (exopolysaccharide) and polyhydroxyalkonates are the most important bacterial polymers which can be profitably used as polymeric material for industrial and medical applications. But it seems to be particularly difficult to achieve a quantitative upgrading of the corresponding extraction, biotechnology and tailor-made synthesis for substantial production at lower prices. Hence, the exploitation of these polymers in various applications will be very difficult until this situation is resolved. Indeed, much awaited is the development of methodologies to increase production of these polymers at affordable prices for more utility. 

Use of MIPs as the tailor made sorbent for solid phase extraction (SPE) in selective enrichment, separation or pre-concentration of pharmaceuticals from the complex natural matrices is one of the important applications of the MIPs. MIPs are widely used as the stationary phase for analytical racemic separations of drugs. MIPs also find the use as in vitro controlled/sustained drug delivery devices, although its application in this field is just at a budding stage. 

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