Isolation using hollow fiber

Djane NK, Malcus F, Martins E, Sawula G, and Johansson G. Hollow fiber cartridges for removal of particulate matter from natural waters prior to matrix isolation and trace metal enrichment using an 8-quinohnol chelating ion exchanger in a flow system. Anal Chim... 

The Use of Hollow-Fiber Ultrafilters for the Isolation of Natural Humic and Fulvic Acids... 

Membrane unit The hollow fiber membranes are PVDF with a pore size of 0.04 pm (nominal). Each unit can be isolated from the rest of the system using automatic bloc-and-bleed valves. 

The principle of dialysis is based on the free movement of small molecules through a semipermeable membrane (thickness 9-30 pm), whereas larger molecules (e.g., proteins) are not able to cross. Small molecules move through diffusion from a high-concentration zone to a low-concentration zone. Scaling down this process to small hollow fiber membranes is referred to as microdialysis. This sample preparation technique can be used to isolate compounds from tissue or other complex samples. In contrast to most other sample preparation techniques used for biological samples, only the unbound free fradion of the analyte is isolated in this method. 

In liquid-phase microextraction (LPME), a liquid membrane is used to enrich and isolate analytes from a complex sample. The liquid membrane, which is immiscible with water and the sample matrix, is immobilized in the pores of a porous hollow fiber. Such a liquid membrane is referred to as a supported liquid membrane (S LM). Immobilization of the SLM is achieved by simply dipping the hollow fiber in an organic solvent allowing the pores to be filled. Figure 9.11 shows a schematic representation of LPME. 

When the gas separation membrane is applied to some practical purposes, the large surface area, that is, large processable capacity for gases is extensively demanded. Since the permeabUity of each membrane is not so high, the membranes are commonly used by integrating them into bundles. The bundle of the membranes is installed into the piping unit (module) and supplied to the user. For the hoUow-fiber membrane, both edges of membrane bundle are finished by epoxy resins, polyurethanes, or sUicone resins in order to isolate the inside of the hollow fibers from the outside of the fibers in the module. 

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