Particle filter beads

Emulsions Emulsions have particles of 0.05 to 5.0 [Lm diameter. The product is a stable latex, rather than a filterable suspension. Some latexes are usable directly, as in paints, or they may be coagulated by various means to produce massive polymers. Figures 23-23d and 23-23 show bead and emulsion processes for vinyl chloride. Continuous emulsion polymerization of outadiene-styrene rubber is done in a CSTR battery with a residence time of 8 to 12 h. Batch treating of emulsions also is widely used. 

When the bacteria to be detected are less than 1% of the total population in a sample, IFAs cannot be used because of interference from unrelated particles that are concentrated when large volumes of sample are filtered. To overcome this problem, the organism of interest may be concentrated by immunomagnetic separation.10,51 62 For this procedure magnetic beads coated with monoclonal or polyclonal antibodies are mixed with the sample. The beads are collected with a magnet, and the cells attached to the beads then are removed, enumerated, and identified by IFAs. 

Many water-soluble vinyl monomers may be polymerized by the emulsion polymerization technique. This technique, which differs from suspension polymerization in the size of the suspended particles and in mechanism, is widely used for the production of a number of commercial plastics and elastomers. While the particles in the suspension range from 10 to 1000 nm, those in the emulsion process range from 0.05 to 5 nm in diameter. The small beads produced in the suspension process may be separated by filtering, but the latex produced in emulsion polymerization is a stable system in which the charged particles cannot be recovered by ordinary separation procedures. 

Supports of different macroscopic shape have been used for solid-phase synthesis. The most common are spherical particles (beads, 0.04-0.15 mm), which are readily weighed, filtered, and dried, and are well-suited for most applications. Other forms of insoluble support include sheets [1], crown-shaped pins [2], or small discs [3]. 

Charcoal coated with dextran Porous beads Filter paper Ammonium sulphate Double antibody Polyethylene glycol Antibody bound to the walls of tubes or to plastic beads or rods Magnetic particles... 

Polystyrene Latex (PSL) Bead Solution Filtration Experiments were conducted to obtain filter retention, flow rate, and Ap data for a DI water based PSL bead mix solution prepared using particles ranging from bead diameters of 0.772 to 20 pm. It is a common practice to use PSL bead challenge solutions (created by mixing different size PSL bead standards in specific volumetric ratio to simulate slurry-like particle size distribution for the bead mix solution) to obtain relative quantitative retention data for various filters. These solutions are expected to retain stable PSD and provide more consistent information compared to real CMP slurries, which may change particle characteristics over time. 

A broad variety of particle sizes are available, from microspheres with less than 5-pm particle size up to resins of 700-pm particle size. The large beads can be used as polymeric microreactors.P l As the separation between resin and liquid is still performed by filtration, different glass filters have to be used the porosity and nominal pore size of these filters are listed in Table 5. In those applications where single beads are used (split/mix, single-bead analysis, bead-based assays) it is essential to know the capacity of the single beads. For practical purposes a correlation between bead size and capacity per bead is reported in Table 6. 

Carefully transfer the sample into the holder of the disk and apply vacuum to aspirate the sample through the disk. If the disk should become dry before addition of the sample, recondition the disk and apply the sample. A vacuum of 12 in. of mercury provides an appropriate flow rate for sample addition. If the sample contains particulates and a large volume is to be filtered, that is, > 100 rnL for a 47-mm disk, the addition of Filter Aid 400 beads (3M) is recommended. Filter Aid 400 is nonporous, inert, and resistant to leaching. It is placed on top of the disk to a depth of about 1 cm. It acts as a depth filter to prevent the suspended solids from plugging the disk. The Filter Aid 400 are silica beads of 40-pm diameter. Again do not allow the disk to go dry after addition of the sample. Because of the high efficiency of the small particle size of the C-18 (10 pm), the sample recovery is unaffected by flow rate and the sample should be past as fast as the extraction disk will allow. 

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