Solid phase principle

Thurman, E. M. Mills, M. S. Solid-Phase Extraction Principles an Practice, Wiley NewYork, 1998. 

E.M. Thurman and M.S. Mills, Solid-phase Extraction Principles and Practice, Chemical Analysis Series Vol. 147, J. Wiley Sons, New York, 1998. ISBN 047161422X. 

Theoretical representation of the behaviour of a hydrocyclone requires adequate analysis of three distinct physical phenomenon taking place in these devices, viz. the understanding of fluid flow, its interactions with the dispersed solid phase and the quantification of shear induced attrition of crystals. Simplified analytical solutions to conservation of mass and momentum equations derived from the Navier-Stokes equation can be used to quantify fluid flow in the hydrocyclone. For dilute slurries, once bulk flow has been quantified in terms of spatial components of velocity, crystal motion can then be traced by balancing forces on the crystals themselves to map out their trajectories. The trajectories for different sizes can then be used to develop a separation efficiency curve, which quantifies performance of the vessel (Bloor and Ingham, 1987). In principle, population balances can be included for crystal attrition in the above description for developing a thorough mathematical model. 

The theory of crystal growth accordingly starts usually with the assumption that the atoms in the gaseous, diluted, or hquid mother phase will have a tendency to arrange themselves in a regular lattice structure. We ignore here for the moment the formation of poly crystalhne solids. In principle we should start with the quantum-mechanical basis of the formation of such lattice structures. Unfortunately, however, even with the computational effort of present computers with a performance of about 100 megaflops... 

DNA synthesizers operate on a principle similar to that of the Merrifield solid-phase peptide synthesizer (Section 26.8). In essence, a protected nucleotide is covalently bonded to a solid support, and one nucleotide at a time is added to the growing chain by the use of a coupling reagent. After the final nucleotide has been added, all the protecting groups are removed and the synthetic DNA is cleaved from the solid support. Five steps are needed ... 

What happens when enough NaOH has been added to remove three protons from each Cr(H20)neutral species Cr(H20)3(0H)j, or Cr(0H)3-3H20. This neutral species has no charges to repel other molecules of its own kind so it precipitates. However, as more NaOH is added to this solid phase, one more proton can be removed to produce Crf OJ OH) - and the Cr(0H)3-3H20 dissolves. [In principle, more protons could be removed, perhaps eventually to form Cr(OH) 3, but there is as yet no evidence for this.]... 

As with other crystalline substances, on heating coordination compounds may melt, sublime, decompose, or undergo a solid phase transition. The greater complexity of the constituents present increases the number of types of bond redistribution processes which are, in principle, possible within and between the coordination spheres. The following solid-state transitions may be distinguished (i) changes in relative dispositions... 

Recently it has been shown that the microwave-assisted decoration of the 2(lff)-pyrazinone scaffold can allow an easy introduction of different substituents at the C-3 and even to the less reactive C-5 position [29]. Taking full advantage of combinatorial principles, some of these pathways were transferred to microwave-enhanced solid-phase chemistry, opening the way for the generation of many biologically interesting structures [108]. 

The availability of functionalized 2(lH)-pyrazinone in combination with the use of microwave accelerated solid-phase chemistry constitutes a sohd foundation for generating large libraries of compoimds suitable for medicinal chemistry. The authors have also shown that the scaffold can be further functionalized using the principles of cUck-chemistry , thereby paving the way towards highly substituted 2-pyridone structures [45-47]. 

A brief discussion of sohd-liquid phase equihbrium is presented prior to discussing specific crystalhzation methods. Figures 20-1 and 20-2 illustrate the phase diagrams for binary sohd-solution and eutectic systems, respectively. In the case of binary solid-solution systems, illustrated in Fig. 20-1, the liquid and solid phases contain equilibrium quantities of both components in a manner similar to vapor-hquid phase behavior. This type of behavior causes separation difficulties since multiple stages are required. In principle, however, high purity... 

Principles and Characteristics Solid-phase extraction (SPE) is a very popular sample preparation and clean-up technique. In SPE solutes are extracted from a liquid (or gaseous) phase into a solid phase. Substances that have been extracted by the solid particles can be removed by washing with an appropriate liquid eluent. Usually, the volume of solvent needed for complete elution of the analytes is much smaller (typically < 1 mL) than the original sample volume. A concentration of the analytes is thus achieved. 

Principles and Characteristics Solid-phase microextraction (SPME) is a patented microscale adsorp-tion/desorption technique developed by Pawliszyn et al. [525-531], which represents a recent development in sample preparation and sample concentration. In SPME analytes partition from a sample into a polymeric stationary phase that is thin-coated on a fused-silica rod (typically 1 cm x 100 p,m). Several configurations of SPME have been proposed including fibre, tubing, stirrer/fan, etc. SPME was introduced as a solvent-free sample preparation technique for GC. 

W. Simpson, Solid Phase Extraction Principles, Strategies and Applications. M. Dekker, New York, NY (1997). 

Principles and Characteristics As mentioned already (Section 3.5.2) solid-phase microextraction involves the use of a micro-fibre which is exposed to the analyte(s) for a prespecified time. GC-MS is an ideal detector after SPME extraction/injection for both qualitative and quantitative analysis. For SPME-GC analysis, the fibre is forced into the chromatography capillary injector, where the entire extraction is desorbed. A high linear flow-rate of the carrier gas along the fibre is essential to ensure complete desorption of the analytes. Because no solvent is injected, and the analytes are rapidly desorbed on to the column, minimum detection limits are improved and resolution is maintained. Online coupling of conventional fibre-based SPME coupled with GC is now becoming routine. Automated SPME takes the sample directly from bottle to gas chromatograph. Split/splitless, on-column and PTV injection are compatible with SPME. SPME can also be used very effectively for sample introduction to fast GC systems, provided that a dedicated injector is used for this purpose [69,70],... 

Kenner GW, McDermott JR, Sheppard RC. The safety catch principle in solid-phase peptide synthesis. J Chem Soc Chem Comm 1971 636-637. 

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