Chemistry: molecular biology and microbiology – Apparatus
Reexamination Certificate
2000-07-17
2001-03-27
Leary, Louise N. (Department: 1623)
Chemistry: molecular biology and microbiology
Apparatus
C435S293100, C435S295300, C435S975000, C422S068100
Reexamination Certificate
active
06207445
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to devices and methods for filtration of a biological fluid and/or extraction of a specific analyte from a suspended particulate.
BACKGROUND OF THE INVENTION
It is often desirable to analyze a specific component, compound, or analyte within a biological fluid such as urine. Frequently, this involves analyzing a liquid or a particulate of the biological fluid. Centrifugation is commonly used to separate a liquid solution from a particulate suspended within the liquid solution. Once separated by centrifugation the fluid is readily available for analysis. If, however, an analyte of interest is in the deposited particulate material, a more complicated process is required. The particulate material must be re-suspended and transferred from a centrifuge tube to an analysis tube. If the particulate material must be extracted prior to analysis, one or more reagents may be introduced directly into the centrifuge tube or may be introduced to the transferred, re-suspended sample in the analysis tube. If, after extraction, the analyte must be separated from other larger particulates, the sample may have to be re-centrifuged or filtered prior to analysis.
There are a number of drawbacks to the use of centrifugation. Centrifugation equipment is costly and requires a substantial amount of space. Centrifugation is a labor burden and a time burden for the operator because the centrifuge has to be loaded and unloaded. Operator error also can occur with centrifugation. Smaller, less expensive centrifugation equipment is available, but this does not eliminate the time required to process a sample, and may increase the processing time to provide adequate separation.
Plunger-like in-container pressure filtration systems have been designed to separate particles from liquid samples being tested in an effort to eliminate the necessity of centrifugation. A number of these systems involve a tube such as a test tube and a plunger mechanism that reciprocates axially within the tube. The plunger mechanism includes a filter unit at a distal end of the plunger mechanism. Downward axial movement of the filter unit via the plunger mechanism compacts particulates in the liquid sample at the bottom of the tube. Any material greater than the pore size of the filter is trapped under the filter assembly. The liquid solution can be decanted or aspirated away.
A problem with these plunger-like devices and similar devices is that they do not allow for easy recovery of the particulate material for subsequent processing. Also, the filter unit is subject to sufficient pressure during the plunging process, which can cause the filter to crack or tear. Often such devices are used with a tapered tube. Upon downward axial movement of the plunger mechanism, the diameter of the plunger mechanism and the filter unit may become the same as the inner diameter of the tapered tube. This may prevent the filter unit from being forced through the solution. If all of the liquid has not been filtered though the device, then residual liquid may contaminate the particulate material. The volume of liquid may not be easily detectable or apparent, but the contamination can be substantial. Forcing the plunger mechanism further into the tube can cause the tube to crack or break. If the plunger mechanism is not designed for removal, additional processing such as extraction of the solid within the same device may be impossible. A more complete multiple unit or multiple module device may be required that includes a removable module designed to capture the solid.
SUMMARY OF THE INVENTION
To this end, a first aspect of the present invention involves an easy to use biological fluid filtration and extraction device that provides a sample directly to an analytical method. The device is capable of providing a clarified liquid ready for analysis or disposal as appropriate for the specific analyte of interest, and is capable of capturing particulate materials and allowing for further processing, i.e., extraction, of those particles directly with the device. Once extracted, the device will deliver a liquid containing the analyte of interest to an analytical method. The device includes a pliant body having an open top end and an internal wall defining an inner chamber. A sealing mechanism is adapted to seal the open top end of the body. A gradient filter assembly including at least one filter is supported within the body by a support assembly. The pliant body is adapted to be squeezed by a user's fingers so as to impart a positive pressure in the chamber sufficient to cause a fluid in the chamber to flow through the filter assembly.
In a preferred embodiment of the filtration and extraction device, the device includes a number of features. A first feature is that the body is tubular and made of polyvinylchloride. A second feature is that the body includes a rigid ring at the top end. A third feature is that the body includes an open bottom end and the support assembly is carried by the body near the open bottom end. A fourth feature is that the sealing mechanism is a polyvinylchloride sealing cap. A fifth feature is that the support assembly includes a nozzle adapted to dispense the fluid from the device. A sixth feature is that the support assembly includes a circular, concave support that supports the filter assembly, and the support includes a plurality of radial support ribs that support the filter assembly. A seventh feature is that the support assembly includes a flat bottom surface for standing the device in an upright position on a flat surface. An eighth feature is that the support assembly is made of a rigid material. An ninth feature is that the filter assembly includes a pore size that ranges from 0.5 to 4 microns. A tenth feature is that the at least one filter is made of polysulfone, nylon, polypropylene, cellulose, or cellulose acetate. An eleventh feature is that the filter is hydrophilic. A twelfth feature is that filter assembly includes a single gradient filter and the effective pore size of the filter is in the range of 0.69 to 0.87 microns. A thirteenth feature is that the filter assembly includes multiple homogeneous filters with at least two of the filters having a different pore size, the multiple filters stacked so that a filter with a smaller pore size is located below a filter with a larger pore size, and a woven nylon membrane is located between filters. A fourteenth feature is that the periphery of the filter assembly is flush with the internal wall of the body.
A second aspect of the invention involves a filtration device including a pliant tubular body having an open end and an internal chamber, means for sealing the open end, a gradient filter assembly including at least one filter, and means for supporting the filter assembly within the tubular body, whereby the pliant tubular body is adapted to be squeezed by a user's fingers so as to impart a positive pressure in the chamber sufficient to cause a fluid in the chamber to flow through the filter assembly.
A third aspect of the invention includes a kit for filtering a biological fluid having particulate matter and liquid, and extracting an analyte from the particulate matter. The kit includes a filtration and an extraction device including a pliant tubular body having an open top end, an open bottom end, and an internal wall defining an inner chamber. The device further includes a cap assembly fixed to the body near the open top end. The cap assembly includes a cap adapted to seal the open top end. The device also includes a support assembly fixed to the body near the open bottom end, the support assembly including a circular support located within the tubular body and a nozzle adapted to dispense fluid from the device. A circular gradient filter assembly including at least one filter is fixed to the support. The pliant body is adapted to be squeezed by a user's fingers so as to impart a positive pressure in the chamber sufficient to cause a fluid in the chamber to flow through the filter assembly. The kit al
Biostar Inc.
Leary Louise N.
LandOfFree
Filtration and extraction device and method of using the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Filtration and extraction device and method of using the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Filtration and extraction device and method of using the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2534682