Cellulose ester membrane filter acetate

Three filtering media commercially available from Millipore Corporation were evaluated for the collection of airborne particulates of the organoarsenical compounds. These were (l) cellulose ester membranes (2) Fluoropore and (3) Mitex. The cellulose ester membrane filters (0.8 ym pore size) are the standard Millipore filters used for aerosol sampling and consist of a mixture of cellulose nitrate and cellulose acetate. The Fluoropore filters are made of Teflon (PTFE) and are bonded to a polyethylene net. Fluoropore filters with a pore size of 1.0 ym were selected for this study. 

A measured volume of air drawn through a 0.8-mm cellulose ester membrane filter the particulates of hydroquinone extracted with 1% acetic acid in water ... 

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. 

Sterile filtration of liquids and gases is now virtually always done using mem brane filters. The first U.S. patent for membrane filters was filed in 1922 and pertained to cellulose acetate membranes. A wide range of membrane filter media are now commercially available to suit various applications cellulose esters, polyvinylidinefluoride, polytetrafluoroethylene (PTFE), and polyhexam-ethyleneadipamide (nylon 66), separately or as laminates with polyethylene, polypropylene, and polyester for more robust phy.sicai characteristics. 

For OM examination tortuous-pore cellulose nitrate (CN), acetate, or mixed ester (CE) membrane filters with a pore size of 0.8 or 1.2 pm are recommended. 

Membrane filters are used to remove particulates from samples and solvents prior to HPLC analysis and also for the preparation of liquid samples, where no solvent is used. Typical materials of construction for membrane filters are usually synthetic polymeric materials, although natural substances, such as cellulose, and inorganic materials, such as glass fibers, are also used acrylic copolymer, aluminum oxide, cellulose acetate, glass fiber, mixed cellulose esters, nitrocellulose, nylon, polycarbonate, polyester, polyether sulfone, polypropylene polysulfone, PTFE, PVC, etc. The compatibility of the polymeric material with the solvents used must be a great concern of their different chemical properties. 

Administration (FDA) considers the sodium, potassium, and calcium propionate salts as safe additives (GRAS), since they are found normally in a number of foods and are metabolized easily by all mammals. Propionic acid is used in the production of cellulose-based plastics (such as cellulose acetate propionate), which are used in textiles, filters, reverse osmosis membranes, sheeting, film products, lacquers, and molding plastics. Propionic acid esters and other derivatives are used as antiarthritic and antibiotic drug preparations, as perfumes and flavors (e.g., citronellyl propionate and geranyl propionate), as plasticizers (e.g., phenyl propionate and glycerol tripropionate), and as specialized solvents. 

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