Ultrafiltration cartridges

Comparison between the inventories in the collected fractions (the colloidal and ultrafiltered fractions) and in the starting sample often indicate that there are losses of nuclides on to the ultrafiltration cartridge. These are largely recovered by subsequent acid rinses of the ultrafilters and filtration system. It is not clear whether the recovered abundances should be considered part of the colloids retained by the filter, or solutes that have adsorbed in the system (Gustafsson et al. 1996 Andersson et al. 2001), even though test experiments with colloidally-bound " Th showed significant losses in the ultrafiltration system (Baskaran et al. 1992.)... 

Disposable Ultrafree-CL (Millipore) ultrafiltration cartridge units (10 kDa nominal molecular weight cutoff). 

The conditioning and control of indoor environments is an ever increasing problem. Lately this does not only include the traditional control of temperature and moisture but also the elimination of contaminants and odors from the atmosphere. Particulates, including organic matter, such as mold, germs, and viruses, can be captured and retained by sometimes electrically assisted ultrafiltration. Cartridges are either discarded or cleaned/reactivated. For the elimination of chemicals and odors, absorption, adsorption, and chemical reactions with air purification media are required. 

One of the advantages of CE is the ability to analyze extraordinarily small sample volumes (injected volumes are typically in the nanoliter range, and total sample volumes of a few microliters are easily accommodated by automated CE systems). Workup of microliter sample volumes is difficult because many HPLC sample preparation methods and devices are scaled for milliliter volumes. Fortunately, many sample preparation devices for handling small volumes have become commercially available in the last few years. These include miniature desalting columns and ultrafiltration cartridges, microdialyzers, and small-scale sorbent extraction devices. Miniaturized techniques for desalting and concentrat-... 

For the determination of particulate mercury, add-cleaned Teflon and quartz fibre filters, the latter combusted at 500 °C (Coquery and Cossa, 1995), are recommended. A significant fraction of the mercury in seawater is present in colloidal forms and separated with the aid of add-cleaned ultrafiltration cartridges (Stordal et oL, 19%). 

The filtration apparatus was composed of a feed tank, a pump, an ultrafiltration cartridge and pressure gauges for feed, reteiitate and permeate. The membranes (table I) were polysulfone (Polymem and Pall) or cellulose acetate (Amicon) with a molecular weight cut-off ranging between 1 kDa and 50 kDa. The module was a flat sheet cassette (Pall) or hollow fibres (Amicon and Polymem). 

In a study of the bioaccumulation of metals as colloid complexes and free ions by the marine brown shrimp, Penaeus aztecus [29] the colloids were isolated and concentrated from water obtained from Dickinson Bayou, an inlet of Galveston Bay, Texas, using various filtration and ultrafiltration systems equipped with a spiral-wound 1 kDa cutoff cartridge. The total colloidal organic carbon in the concentrate was found to be 78 lmgdm 3. The shrimps were exposed to metals (Mn, Fe, Co, Zn, Cd, Ag, Sn, Ba and Hg) as radiolabelled colloid complexes, and free-ionic radiotracers using ultrafiltered seawater without radiotracers as controls. The experiments were designed so that the animals were exposed to environmentally realistic metal and colloid concentrations. 

SPEC was essentially able to market their Zr02-based ultrafiltration membranes to an already existing market in the sense that these membranes replaced polymeric UF membranes in a number of applications. They also developed a certain number of new applications. For Ceraver, the situation was different. When the Membralox membranes were first developed, microfiltration was performed exclusively with dead-end polymeric cartridge filters. In parallel to the development of inorganic MF membranes, Ceraver initiated the development of cross-flow MF with backflushing as a new industrial process. 

Removing Small Molecular Weight Contaminants. Ultrafiltration in hollow fiber membrane cartridges was the best method found to remove small molecular weight materials (75). It also served to concentrate the enzymes and change the buffer (via diafiltration) to that required for the next purification step. A 10,000 mwt... 

However, the short lifetime of in-line cartridge filters makes them unsuitable for microfiltration of highly contaminated feed streams. Cross-flow filtration, which overlaps significantly with ultrafiltration technology, described in Chapter 6, is used in such applications. In cross-flow filtration, long filter life is achieved by sweeping the majority of the retained particles from the membrane surface before they enter the membrane. Screen filters are preferred for this application, and an ultrafiltration membrane can be used. The design of such membranes and modules is covered under ultrafiltration (Chapter 6) and will not be repeated here. 

Figure 3-4. Ultrafiltration by centrifugation. Ultrafiltration by centrifugation is particularly well suited for relatively small volumes. The solution is introduced into the upper chamber of the centrifugation cartridge, and on centrifu-...

Hemofiltration (HF) is a similar modaUty whereby solute is removed by convection. The hemofiltration apparatus differs from HD in that no dialysate circuit is present. Rather, blood within the cartridge is subject to pressure across a high-flux (large pore) membrane creahng an ultrafiltrate of solutes and water while cells and large solutes remain in the blood and return to the circulation. Hemofiltration typically requires replacement of fluid and electrolytes lost in the ultrafiltrate. 

The next method of pretreatment which was tried was ultrafiltration. Pilot size UF units using the hollow fiber bore flow type cartridge and the 1" tube module were tested. As would be expected, the permeate from the UF unit was quite clear and when used as feed for the RO, absolutely no fouling was apparent. 

This brief overview describes some experiences using tangential-flow and dead-end ultrafiltration techniques for concentration of eukaryotic cells, proteins and virus. The data and conclusions presented here have been drawn from process development work employing available apparatus and should be considered preliminary, rather than definitive or exhaustive. Previous ultrafiltration systems have been described (1-14) for both bench and pilot scale separations of proteins and virus. This paper primarily summarizes work on cartridge and sheet filter systems and their application to processes requiring sterilizable and contained systems. 

A practical method for concentration and purification of wine is to perform an ultrafiltration followed by dialysis of the sample by low cutoff membranes (i.e., 3.5 kDa). If quantitative recovery is not required, it is possible to remove most polyphenols by passing the sample through a Ci8 cartridge (Curioni et al., 2008). A method for quantitative recovery of proteins from wine and to remove phenols is summarized in Table 10.4 (Vincenzi et al.,2005). 

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