Solid-phase materials

Sixteen solid-phase materials were tested on a laboratory scale and the antho-cyanin and sugar content of collected fractions were determined. Among these, reverse-phase silica gels and macroreticular non-ionic acrylic polymer adsorbents such as Serdolit PAD IV or Amberlite XAD-7 turned out to be most suitable. SPE was used to investigate these materials on an enlarged scale, improving elution gradient and column purification. Amberlite XAD-7 was successfully applied in a middle-scale separation. ... 

Despite its advantages, SFE is employed routinely in only a few pesticide laboratories, for the extraction of low-moisture samples such as grains, pulses, dried fruit and tea. The technique requires specialized equipment because the extractions are performed at high pressure (45 psi) and elevated temperatures (around 60 °C) to maintain aC02 density ofO.85 gmL The analyte(s) may be trapped on Cig solid-phase material and eluted with a small volume (around 5 mL) of a polar solvent, such as acetonitrile. 

Particulates include solid-phase materials entrained in the raw product gas as it exits the gasifier. They include the inorganic ash that is associated with mineral matter in the biomass feedstock, unconverted biomass in the form of char, or material from the gasifier bed. 

In matrix solid-phase dispersion (MSPD) the sample is mixed with a suitable powdered solid-phase until a homogeneous dry, free flowing powder is obtained with the sample dispersed over the entire material. A wide variety of solid-phase materials can be used, but for the non-ionic surfactants usually a reversed-phase C18 type of sorbent is applied. The mixture is subsequently (usually dry) packed into a glass column. Next, the analytes of interest are eluted with a suitable solvent or solvent mixture. The competition between reversed-phase hydrophobic chains in the dispersed solid-phase and the solvents results in separation of lipids from analytes. Separation of analytes and interfering substances can also be achieved if polarity differences are present. The MSPD technique has been proven to be successful for a variety of matrices and a wide range of compounds [43], thanks to its sequential extraction matrices analysed include fish tissues [44,45] as well as other diverse materials [46,47]. 

S = solid phase material (i. e., suspended matter, sediment or soil concentration, on a part/part basis), and... 

X = mass of sorbed pollutant/mass of solid phase material). 

Generally, there is no simple and easy theoretical procedure which can provide exact or nearly precise quantitative predictions of what and how much will be adsorbed/desorbed by any solid phase over a period of time [9, 136-139]. Understanding sorption/desorption characteristics of any solid phase materials requires two main laboratory experimental techniques (a) batch equilibrium testing, and (b) continuous solid phase column-leaching testing. These involve... 

Generally, slow sorption or desorption has made complete remediation technology difficult. However, there have recently been legitimate questions raised by some researchers [163,187] about whether we even need to be concerned about residues that desorb so slowly and thus are apparently largely bio-unavailable. At a minimum, it is important that we understand the factors which govern slow sorption/desorption rates, their kinetics and causes at the intra-particle level of different solid phase materials (e.g., surface/subsurface and aquatic sediment particles), and how these phenomena can relate to contaminant transport, bioavailability, toxicity, remediation, and risk assessment modeling. 

In some cases, the eluate from a MSPD column is adequately clean. However, additional steps are often required to remove coeluted matrix components either by using other solid-phase materials packed at the bottom of the MSPD column or by eluting analytes from the MSPD column directly onto a second SPE... 

Matrix solid-phase dispersion techniques have also been suggested for the determination of aminoglycoside residues in bovine tissues (19, 20). The solid-phase material employed in these methods was a cyanopropylsilyl (CN) sorbent. 

As a contaminant moves through soil and groundwater, chemical processes will affect both contaminant concentration and overall hydrogeochemistry (Schoonen, 1998) of the system. Different adsorption mechanisms cause pollutants to adsorb onto the soil, volatilize, precipitate, and be part of the oxidation-reduction processes. Adsorption is loosely described as a process in which chemicals partition from a solution phase into or onto the surfaces of solid-phase materials. Adsorption at particle surfaces tends to retard contaminant movement in soil and groundwater. 

UV-vis technology finds use in a wide variety of applications that cut through a cross section of industry. Applications exist for gas, liquid, and solid phase materials and range from chemical concentration, to color measurement, to film thickness determinations. We will discuss only a few of these in detail here. 

Opportunities remain to develop new or improved separation chemistries, and the engineered solid-phase materials that utilize them, in order to support radioanalyti-cal needs. Selectivity remains a key issue in order to support isolation of particular elements or groups of elements from complex sample matrixes. Selectivity to support determination of TRU actinides in the presence of large excesses of uranium is often required. The engineered form is also significant, as it must enable the separation chemistry to work while providing a robust material that can be used over and over again. 

Chromatography is a very versatile technique offering a wide range of solid phase materials and detector types which can deal with very complex mixtures. In practice all materials and conditions used in the instrument are carefully chosen to match the type of sample mixture involved. This includes selection of stationary phase (chemical and physical properties) column type and length sample pretreatment, operational temperatures, pressures, and flow rates physical and chemical nature of mobile phase detector type and so forth. Detection to nanogram level is quite common and some systems can detect to picogram level using very small volumes of sample. 

In spite of the sensitivity of the determination, because of the low concentrations of cadmium in most environmental samples, the element is still often preconcentrated. For example, discrete nebulization flame AAS has been used to measure foliar cadmium after extraction of the APDC complex into chloroform.15 Cobalt was extracted at the same time. Many other solvent extraction procedures have been described.1 Alternatively resins such as a chelating polydithiocarbamate resin have been employed to concentrate cadmium prior to determination.16 Extractions onto solid phase materials for preconcentration may be made more convenient by automation, for example using flow injection methodology.17... 

Most generally during elution, the liquid flow is reversed and the resin bed is therefore packed. In contrast to conventional complex initial feedstock treatments, fluidized-bed processes combine clarification, expressed product specific capture, and concentration into a single step. Residence time distribution analysis showed a small degree of axial dispersion and the generation of a few dozen theoretical plates that are enough for a good efficiency of the capture step. The efficiency of the separation is, however, dependent on the particle size of the solid phase material. 

Photoelectron spectroscopy of valence and core electrons in solids has been useful in the study of the surface properties of transition metals and other solid-phase materials. When photoelectron spectroscopy is performed on a solid sample, an additional step that must be considered is the escape of the resultant photoelectron from the bulk. The analysis can only be performed as deep as the electrons can escape from the bulk and then be detected. The escape depth is dependent upon the inelastic mean free path of the electrons, determined by electron-electron and electron-phonon collisions, which varies with photoelectron kinetic energy. The depth that can be probed is on the order of about 5-50 A, which makes this spectroscopy actually a surface-sensitive technique rather than a probe of the bulk properties of a material. Because photoelectron spectroscopy only probes such a thin layer, analysis of bulk materials, absorbed molecules, or thin films must be performed in ultrahigh vacuum (<10 torr) to prevent interference from contaminants that may adhere to the surface. 

Heckel A, Mross E, Jung KH, Rademann J, Schmidt RR. Oligosaccharide synthesis on controlled-pore glass as solid phase material. Synlett 1998 2 171-173. 

Solubility of phenanthrene in SDS or APU solutions was determined using mixture of radiolabeled phenanthrene and nonlabeled phenanthrene. A concentrated phenanthrene solution (lOOg/L) was prepared in methylene chloride. 2mL of the concentrated phenanthrene solution was added into 20mL glass vials equipped with an open-port screw cap, which was fitted with a Teflon-lined septum. After evaporation of methylene chloride, SDS or APU aqueous solutions (lOmL) of various concentrations were added into the vials. The vials were sealed and gently shaken in the rotary tumbler for 5 days. After equilibrium, 5mL of the samples were withdrawn and centrifuged at 15000g to separate solid-phase materials from aqueous-phase materials. ImL of the supernatant was... 

Preparation of Solid Phase Antibody. There are many chemical and physical methods by which antibodies may be linked to different solid phase materials. Unfortunately relatively little work has been carried out to investigate systematically the properties of the different methods and materials. The main desirable characteristics are (a) convenience of handling and standardization both in preparation and in utilization b) adequate amount of antibody bound and stability of the preparation both in terms of the binding to solid phase and on storage (c) a low degree of nonspecific binding on the subsequent addition of antigen and labeled antibody. 

The primary requirement for a solid phase material is either that it be capable of nonspecifically adsorbing useful amounts of the desired reagent (usually a protein) or that it be possible to chemically link the solid phase to the reagent. Since the solid phase in an immunoassay is usually used only once and discarded, it is also desirable that the material be relatively inexpensive and obtainable in quantity. Ready availability of large, uniform lots of solid phase material (e.g., plastic) is important for test reproducibility. Uniformity in the total surface area on which the immune reactions take place is important for precision thus the shape of the solid phase is important. Solid phases that have been used for RIA or ELISA include the following ones ... 

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