Chemistry: molecular biology and microbiology – Apparatus – Including condition or time responsive control means
Patent
1990-02-26
1993-05-04
Housel, James C.
Chemistry: molecular biology and microbiology
Apparatus
Including condition or time responsive control means
435 735, 435310, 422101, 422102, 210232, 2103231, 210404, 2104161, G01N 3353, B01D 2400
Patent
active
052081613
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the preparation of samples for assay where filtration and ready access to material retained are required.
In particular the invention addresses the need for many assays to be routinely, quickly and simply carried out in an inexpensive way and where therefore filtration equipment that is complicated and expensive to make and use will not serve.
With these requirements in mind the invention provides an assay filter unit having single or multiple filter stations and a filter at the or each station, characterised in that the filter of the or each station is sealed into the body of the unit to prevent any passage of material to be assayed round the edge of the filter but is removable by breaking out together with the filtering area of the filter the central portion of a filter support grid lying below the filter, along a predetermined line of weakness in the grid, for assay of material retained on the filter.
Such units may be used if desired in filtration assemblies comprising the assay filter unit and corresponding pre-filter unit(s), stacked for passage of filtrate from the pre-filter unit(s) to the assay filter unit.
As noted, the assay filter units may be single or in multi-station form, for example a multi-station block used alone or with separate pre-filter units.
Conveniently the line of weakness is provided by notches of vee or other stress-concentrating form (as seen insection axially of the filter station) formed in elements of the grid at its periphery.
For ease of production and use it is preferred that the body of the assay unit and the grid are integrally formed of plastics by injection moulding and the axial thickness of the elements of the grid at the notches is 0.15 to 0.5 mm, desirably 0.2 to 0.3 mm, thereby allowing both for ready flow of material during moulding and for ready breaking out of the grid after use.
Conveniently the assay filter unit, of plastics, has a plastics ring clamping the filter against the periphery o the support grid, welded (particularly ultrasonically welded) in place. In this construction it is desirable that the assay filter unit body and the ring where they abut the filter have a surface roughness of up to 0.5 microns to improve grip on the filter. Such roughness can be given by controlled sand blasting of the appropriate parts of injection moulds in which the units and rings are to be produced, and the grip it gives leads to the filter breaking out cleanly with the grid.
The invention further provides, for use with the single filter station units, a suction manifold having a plurality of stations for reception of a corresponding number of units and an anvil over which, successively, the body of each unit can be placed to break out the support grid.
In a particular application the invention may provide filtration assemblies as above for carrying out a microbiological assay for detecting a predetermined microorganism or cell in a sample containing particles larger than the predetermined microorganism or cell, each assembly including at least one first filter unit (pre-filter unit) including an open container with a filter having pores large enough to permit the passage therethrough of the predetermined microorganism or cell and small enough to prevent the passage therethrough of the particles larger than the predetermined microorganism or cell, and at least one second filter unit (assay filter unit), vertically interstackable with its respective first such unit, including an open container with a filter having pores large enough to permit the passage therethrough of aqueous liquid and small enough to retain the predetermined microorganism or cell, the filter of the or each second filter unit being, as before, sealed into the unit by a retaining ring or other means preventing any passage of material round the edge of the filter but removable from the unit by breaking out, along a predetermined line of weakness, a filter support lying below the filter, in order to conduct assay.
In such an application as many successively smaller-pore pre-fi
REFERENCES:
patent: 3730352 (1973-05-01), Cohen et al.
patent: 3907505 (1975-09-01), Beall et al.
patent: 3956125 (1976-05-01), Strutt et al.
patent: 3986960 (1976-10-01), Wire et al.
patent: 4255522 (1981-03-01), Fusenig et al.
patent: 4304865 (1981-12-01), O'Brien et al.
Cole Parmer ('85-'86) p. 179.
Fisher '86 p. 736.
Webster's 9th New Collegiate Dictionary p. 808.
Manns Roy L.
Saunders Anthony J.
Bhat N.
Housel James C.
Polyfiltronics N.A., Inc.
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