Coated glass fiber filters

HPLC methods with fluorescence detection have also been developed for the determination of nitro-policyclic aromatic hydrocarbons (PAHs) (among which 9-nitroanthracene and 1-nitronaph-thalene) [238] in atmosphere. Samples have been collected in a standard high-volume sampler with a Teflon-coated glass fiber filter, and the Soxhlet extraction was performed with dichloromethane as the solvent. RP HPLC/UV techniques are used for the determination of aldehydes, ketones, and carbonylic compounds after derivatization with DNPH [239],... 

Adsorption differences between ligand and binding protein (coated glass fiber filters, nitro-cellulose/PVDF membranes, polylysin-coated microtiter plates)... 

Problems appear when the radioactive ligand unspecifically adsorbs in larger quantities to the coated glass fiber filters. This behavior is exhibited by (for example) peptides with negative... 

Protein (e.g., BSA at 0.1 mg/ml) in the binding and/or washing buffer also helps keep the nonspecific binding down. Of course, the ligand may not interact with the BSA, and the BSA must not use up the protein binding capacity of the chosen assay (e.g., of the PEI-coated glass fiber filter). 

In some cases, the filter is used as both particulate trapping medium and as a substrate for holding a derivatizing reagent that reacts with and stabilizes the particulate matter. For example, l-(2-pyridyl)pip-erazine-coated glass fiber filters are used to trap and react with particulate methylene bisphenyl isocyanate to form a derivative that is then analyzed using HPLC coupled with a fluorescence detector. 

Figure 2. Schematic diagram of column tip, second version. 1, Fused-silica column I.D. 0.22 mm 2, chromatographic bed 3, glass fiber filter frit 4, drawn-out 50 ym fused-silica tube 5, high temperature epoxy coating...

Glass fiber filters were coated with BioBrene and run for three preconditioning cycles. The 494HS 6 mm filters were treated with 750 pg of BioBrene and the 494HT 9 mm filters were treated with 1000 pg of BioBrene . 

Other groups used carbonate scrubbers, glass fiber filters impregnated with potassium hydroxide and, prefilters impregnated with sodium hydroxide to specifically remove sulfur dioxide from sample air streams. Other methods have included the use of ferrous sulfate (FeS04), potassium-iodide-coated filter paper, and neutral aqueous potassium iodide solution. 

HIDY The filter media used in this study was a teflon-coated glass fiber substrate, manufactured for us under very strict specifications. It was used uniformly for all aerosol sampling in the SURE. The filter medium is not subject to a sulfur dioxide adsorption artifact, but it is subject to adsorption of nitric acid. It does not adsorb NO or NO2, however. 

Inorganic membranes, usually appUed when high temperatures or chemically active mixtures are involved, are made of ceramics [171,172], zirconia-coated graphite [173],silica-zirconia [174],zeolites [168], or porous glass [175] among others [176]. Ceramic membranes are steam sterilizable and offer a higher mechanical stability [134], thus they may be preferably used in aseptic fermentations, since some hollow fibers are only chemically sterilizable and not very suitable for reuse. Composite materials, in which glass fiber filters are used as support for the polymerization of acrylamide monomers, were developed for the hydrolysis of penicillin G in an electrically immobilized enzyme reactor. By careful adjustment of the isoelectric point of amphoteric membranes, the product of interest (6-aminopenicillanic acid) was retained in an adequate chamber, adjacent to the reaction chamber, while the main contaminant (phenyl acetic acid), was collected in a third chamber [120]. 

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