Method of filtering a fluid and apparatus therefor

Abstract

An apparatus and a method for dividing a fluid into desired proportions by means of a filtering device. In one aspect, this invention provides a method for dividing a fluid into desired portions, the method comprising the steps of: (a) providing at least one filtration device, the filtration device comprising a filter; (b) adding the fluid to the at least one filtration device, the fluid containing material dissolved or suspended therein; (c) placing the at least one filtration device to which fluid has been added in a pressure vessel, the pressure vessel capable of withstanding a specified level of pressure relative to ambient pressure; (d) forming a trapped volume downstream of the filter; (e) increasing the pressure in the pressure vessel upstream of the filter; (f) allowing a period of time to elapse, the period of time being sufficient to allow the pressure downstream of the filter in the trapped volume to be substantially equal to the pressure upstream of the filter; (g) unsealing the filtration device; and (h) venting the pressure vessel. One type of fluid that is particularly amenable to the method of this invention is a solution containing proteinaceous material dissolved therein. In this type of fluid, the solvent is typically an aqueous solvent. In another aspect, this invention provides an apparatus for dividing a fluid into portions.

What is claimed is:  
     
         1 . A method for dividing a fluid containing material dissolved or suspended therein into desired proportions, said method comprising the steps of: 
 (a) providing at least one filtration device, said filtration device comprising a filter;    (b) adding said fluid to at least one filtration device;    (c) placing said at least one filtration device to which said fluid has been added in a pressure vessel, said pressure vessel capable of withstanding a specified level of pressure relative to ambient pressure;    (d) forming a trapped volume downstream of said filter;    (e) increasing the pressure in said pressure vessel upstream of said filter;    (f) allowing a period of time to elapse, said period of time being sufficient to allow the pressure downstream of said filter in said trapped volume to be substantially equal to the pressure upstream of said filter;    (f) unsealing said trapped volume; and    (g) venting said pressure vessel.    
     
     
         2 . The method of  claim 1 , wherein said filter is a porous membrane.  
     
     
         3 . The method of  claim 1 , wherein said material suspended or dissolved in said fluid comprises a protein.  
     
     
         4 . The method of  claim 1 , wherein said pressure in step (e) exceeds the initial pressure in said trapped volume.  
     
     
         5 . The method of  claim 4 , wherein the size of said trapped volume and the levels of pressure and vacuum determine the proportion of fluid that will be retained upstream of said filter.  
     
     
         6 . The method of  claim 1 , wherein the pressure in said pressure vessel is reduced prior to step (d).  
     
     
         7 . An apparatus for dividing a fluid containing material dissolved or suspended therein into desired proportions, said apparatus comprising: 
 (a) a pressure vessel, said pressure vessel capable of withstanding a specified level of pressure relative to ambient pressure;    (b) means for supporting at least one filtration device having a filter;    (c) means for sealing said at least one filtration device, whereby a trapped volume can be created downstream of said filter of said at least one filtration device inserted into said pressure vessel;    (c) means for providing negative pressure or positive pressure or negative and positive pressure relative to ambient pressure within said pressure vessel; and    (d) means for venting said pressure vessel.    
     
     
         8 . The apparatus of  claim 7 , wherein said pressure vessel comprises a chamber and a cover.  
     
     
         9 . The apparatus of  claim 7 , wherein said means for sealing said at least one filtration device comprises a seal located between said filtration device and a rack for holding said at least one filtration device.  
     
     
         10 . The apparatus of  claim 9 , wherein said means for sealing said at least one filtration device further comprises a filtration device clamp assembly.  
     
     
         11 . The apparatus of  claim 10 , wherein said filtration device clamp assembly comprises a filtration device clamp and means for biasing the filtration device clamp toward said filter.  
     
     
         12 . The apparatus of  claim 11 , wherein said means for biasing comprises a spring.  
     
     
         13 . The apparatus of  claim 12 , wherein variation of force of said means for biasing provides variation in the proportion of fluid retained upstream of said filter.  
     
     
         14 . The apparatus of  claim 10 , wherein said means for sealing said at least one filtration device further comprises an upper clamp plate and a lower clamp plate.  
     
     
         15 . The apparatus of  claim 14 , wherein said means for sealing said at least one filtration device further comprises at least one spacer for separating said upper clamp plate from said lower clamp plate.  
     
     
         16 . The apparatus of  claim 7 , wherein size of said trapped volume can be varied to provide variation in the proportion of fluid retained upstream of said filter.