Nylon membrane filter

Mobile phase The HPLC mobile phase is made up as follows. Prepare 2 L of acetate buffer by dissolving 13.6 g of sodium acetate and 6 mL of glacial acetic acid in 2 L of deionized water. Adjust the solution to pH 4.8 with concentrated sodium hydroxide solution (or glacial acetic acid) if necessary. Mix 2 L of buffer with 1.6-2 L (the amount depends on the particular commodity) of methanol. Eilter the solution through a 0.22-pm Nylon 66 filter membrane before using the mobile phase Absolute ethanol Aaper Alcohol and Chemical Co. (200 proof)... 

FEP Teflon FEP membrane PMSP Poly(1-trimethylsilyl-l-propyne) membrane Nz Enzyme immobilized Nylon filter... 

Organic solvents used for liquid chromatography were from OmniSolv (MCB Manufacturing Chemists, Tnc., Cincinnati, OH) and water was distilled, deionized and filtered through a 0.2u nylon 66 membrane (Rainin). All chemicals with no source identified were of reagent grade. 

Treatment of the filter membrane to ensure fixing of the recombinant A DNAs depends on the type of membrane used. Nitrocellulose requires only heating (68°, overnight), whereas nylon requires UV light treatment (see vendor s instructions). 

Abdel-Hamid et al. [122] used a flow-injection amperometric immunofll-tration assay system for the rapid detection of total E. coli and Salmonella. Disposable porous nylon membranes served as a support for the immobilization of anti- ]. coli or anti-Salmonella antibodies. The assay system consists of a flow-injection system, a disposable filter-membrane, and an amperometric sensor. A sandwich immunoassay specifically and directly detected 50 cells ml total E. coli or 50 cells ml Salmonella. The immunosensor can be used as a highly sensitive and automated bioanalytical device for the rapid quantitative detection of bacteria in food and water. 

Immediately after the samples have entered the membrane, add approx 0.4 mL of 1.0 M Tris-HCl (pH 7.4)/2 M NaCl (sterile and filtered through an 0.22-pm nylon filter) to each sample well and allow it to enter the membrane. Then add approx 0.4 mL of sterile, filtered 20X SSC to each well and allow it to enter the membrane. 

Membrane filtration application to biopharmaceutical product development is extremely important since sterile protein-peptide products can only be prepared via sterile filtration and gamma radiation steam cannot be used under pressure. There are several excellent works in the field of sterile membrane filtration.34-36 The filter media most often tested for protein formulations with minimum adsorption and maximum compatibility are mixed esters of cellulose acetate, cellulose nitrate, polysulfone, and nylon 66. Membrane filters must be tested for compatibility with the active drug substance and selected for formulations if they have the lowest adsorption and maximum compatibility with the product. 

Immobilization of proteins from solutions has been discussed in Section 13.3. Several matrices can be used for the transfer of proteins from gels, the most widely used being nitrocellulose. Other alternatives are diazobenzyloxymethyl-cellulose (DBM filters Alwine et al., 1979), diazophenylthioether-cellulose (DPT filters Reiser and War-dale, 1981), cellulose-acetate or paper activated with CNBr (Clarke et al., 1979), commercially available nylon-based membranes such as Gene screen (New England Nuclear), Zetabind (available from Bio-Rad as Zeta Probe). Nitrocellulose is better for EIA than Zeta Probe (considerably less background). 

Procedure. Two separate procedures were employed, referred to as system I and system II below. System I consisted of a nonpolar C-18 column and a polar CN column, both used with a mobile phase containing e-CD. The mobile phase was prepared by dissolving the appropriate quantity of e-CD in distilled water, aqueous 10% methanol, or aqueous 20% methanol, followed by filtration through a 0.45 ym Nylon-66 membrane filter (Rainin Instruments, Woburn, MA). System II consisted of a nonpolar C-18, a e-CD, and a Y-CD column, and the mobile phase was water containing an organic modifier. The mobile phase was prepared by adding the appropriate quantity of methanol to distilled water containing 0.05 M sodium acetate buffer. 

In conventional membrane emulsification, droplets are formed at the membrane surface and detached from it by wall shear stress of the continuous phase (Figure 20.8, middle) [29,45,46]. In addition to tubular membranes made from ceramics such as aluminum oxide, special porous glasses such as SPG (Shiratsu Porous Class) membranes and polymers such as polypropylene (29, 47, 48], flat filter membranes made of PTFE [49, 50], nylon [51] and silicon (30, 51-55] have been used in emulsification. Silicon membranes are produced by microengineering techniques. This technology offers the possibility to influence precisely the structure of a membrane (arrangement of pores, pore shape, size and distance, porosity, surface characteristics, as shown in Figure 20.7). Very thin active layers reduce the pressure drop without losing mechanical stability. 

Nylon solvent filters, Phenomenex filter membranes. 0.45 Xm, 47 mm. 

Membrane cartridge filters are extremely flexible and high in tensile strength. The cartridge construction is based on a multi-layer combination of filter media in pleated format. Those polymers that have been used extensively as filtration media in coarser grades are now widely used as membrane filters. A typical format has a cartridge fabricated from a pleated filter pack, which contains a very fine polyolefin fibre prefilter layer, two nylon membranes of the same pore (0.2 pm) size, and a downstream polypropylene support. The layers of nylon microporous membrane and polypropylene prefilter are pleated together and snpported by an inner snpport core. The end-caps and core are melt sealed in polypropylene. 

Because membrane filtration is the only currently acceptable method of sterilizing protein pharmaceuticals, the adsorption and inactivation of proteins on membranes is of particular concern during formulation development. Pitt [56] examined nonspecific protein binding of polymeric microporous membranes typically used in sterilization by membrane filtration. Nitrocellulose and nylon membranes had extremely high protein adsorption, followed by polysulfone, cellulose diacetate, and hydrophilic polyvinylidene fluoride membranes. In a subsequent study by Truskey et al. [46], protein conformational changes after filtration were observed by CD spectroscopy, particularly with nylon and polysulfone membrane filters. The conformational changes were related to the tendency of the membrane to adsorb the protein, although the precise mechanism was unclear. 

All water samples were collected in amber-polyethylene terephtalate (PET) bottles and were kept at 4°C during shipment. Upon reception in the laboratory, samples were vacuum filtered through 1 pm glass fiber filters, followed by 0.45 pm nylon membrane filters, and were stored in the dark at —20°C until analysis. 

Porous polymers, e.g. a membrane filter or a nylon capsule [35], are soaked in organic solvents containing bilayer forming amphiphiles and then dried. 

Eiltration with nylon membrane filters sonication of the filters with three volumes of toluene rotavaporation and reconstitution in a 1.5 mL of toluene-methanol (2 1, v/v) mixture... 

---