Solid phase extraction goals

The most widely employed techniques for the extraction of water samples for triazine compounds include liquid-liquid extraction (LLE), solid-phase extraction (SPE), and liquid-solid extraction (LSE). Although most reports involving SPE are off-line procedures, there is increasing interest and subsequently increasing numbers of reports regarding on-line SPE, the goal of which is to improve overall productivity and safety. To a lesser extent, solid-phase microextraction (SPME), supercritical fluid extraction (SEE), semi-permeable membrane device (SPMD), and molecularly imprinted polymer (MIP) techniques have been reported. 

Before any sample can be subjected to chromatography, some type of sample preparation is required, which can be as simple as filtration or an involved solid-phase extraction protocol. Sample preparation is that activity or those activities necessary to prepare a sample for analysis. The ultimate goal of sample preparation is to provide the component of interest in solution, free from interferences and at a concentration appropriate for detection. This entry will briefly discuss seven topic areas included in sample preparation standard methods, solid-phase extraction (SPE), matrix solid-phase dispersion (MSPD), solid-phase microextraction (SPME), microdialysis, ultraliltration (UF), and automated systems. 

There are other useful techniques available to the isolation chemist that can be incorporated into the isolation process to support the overall isolation goal. Solid-phase extraction (SPE) and liquid-liquid extraction are commonly used techniques that are part of the isolation chemist s tool chest that can be used in clever ways. SPE also offers great potential in purifying the isolated product because of its universal-... 

Though several studies (5-9) have described the concentrations of trace elements in surface waters, most of them did not differentiate between species of a particular element. Some (10) have considered the distribution between dissolved and particulate forms. However, few attempts (11) have been made to evaluate the distribution of metals between various solid phase components of the suspended material. The present study provides quantitative estimates of dissolved (dissolved is defined as those aquatic components that could not be removed by centrifugation from liquid phase) and various solid phase associated metal fractions in southeastern United States streams. Between November 83 and August 85, 46 bi-weekly samples were taken from six SRP associated watersheds to determine dissolved (filterable) and total element concentrations. As one of several goals of the study was to assess the impact of natural and production related activities on trace element behavior in these aquatic systems, knowledge of speciation within solid and dissolved phases was essential for data interpretation. The research described herein used sequential extraction and a thermodynamics approach to define solid and dissolved phase species of Cu, Cd, Fe, Mn, Ni and Zn. The study also evaluated the effects of natural and production related processes on the distribution of metals in aquatic systems at SRP. 

The goal of this research was to develop an organic solvent-free technique to determine the concentrations of the active ingredients of rosemary in the water phase after the hot water extraction at 100 °C. Hot water extraction was used to simulate the cooking process, and the water extracts from the hot water extraction were then used as samples for solid-phase microextraction followed... 

In initial purification steps the goal is to obtain concentration with partial purification of the product, which is recovered either as a precipitate (precipitation), a solution in a second phase (liquid-liquid extraction), or adsorbed to solids (adsor ptiou, chromatography). 

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