Solid phase extraction plate with silica disks

Details Solid phase extraction plate with silica disks Solid phase extraction plate with silica disks

1998-12-21

2001-03-13

Thornton, Krisanne (Department: 1744)

Chemical apparatus and process disinfecting, deodorizing, preser

Control element responsive to a sensed operating condition

C422S105000, C436S180000, C436S809000

Reexamination Certificate

active

06200533

ABSTRACT:

The present invention generally relates to assay assemblies for use in the analysis of liquids by a batch process and is more particularly directed to a solid phase extraction plate for the determination of chemical, bio-chemical or biological nature of various liquids.
Because of the need for the analysis, or assay, of a great number of small quantities of liquids, array trays and assemblies have been developed whereby individual samples of test liquid are prepared and subjected to analysis by multi-test processing utilizing various extraction mediums.
Devices of this type may include a separation medium to which the liquid for analysis are subjected with the medium serving to remove solid/particulate matter from the liquid by filtration or serving as a form of chromatographic medium for selectively separating or indicating a particular characteristic of the fluid being assayed.
A typical prior art solid phase extraction plate assembly is shown in U.S. Pat. No. 5,417,923. The assay trays typically have a plurality of wells, for example, 96, arranged in rows and columns in which the solid phase extraction medium is placed and sequentially treated with liquid reagents and washes involved in the assay of interest.
It should be appreciated that this type of assay tray typically has dimensions in the order of 3 inches by 5 inches, hence, a 96 compartment, or well, assay tray has very small compartment diameters. Allowing for supporting for wall structure, a typical
96
well assay tray having the wells arranged and a typical 8×12 configuration will have well diameters in the order of 0.3 inches.
Accordingly, while the tray with the compartments, or wells, may be formed by injection molding, the insertion of separation medium into each well and the physical requirement of positively supporting the medium within each individual well can be a tedious time-consuming procedure.
Typically, not only is it required to dispose a separate medium in each well, but also a means for fixing or holding the medium in the well in a position suitable for separation, or reaction, with liquids later disposed in the well for assay purposes.
Heretofore, separation mediums, either in particulate form or in slug, or disk, form have been supported in wells structure by means of frits, or retaining rings, see for example, the structure shown in U.S. Pat. Nos. 5,205,989, 5,264,184, 5,283,039 and 5,417,923.
Given the size of the wells, or compartments, in the
96
well assay tray, it can be easily appreciated that the assembly of the small extraction mediums and retainer rings is extremely tedious and, of course, time-consuming and expensive.
The present invention provides for a solid phase extraction plate having simplified construction which does not require the use of frits, or the like, and accordingly, enables significant cost-savings in the assembly thereof.
SUMMARY OF THE INVENTION
A solid phase extraction plate in accordance with the present invention generally includes a unitary tray having a plurality of spaced-apart discrete, upstanding chambers molded therein. Each chamber includes a top opening and a bottom nozzle. A plurality of solid phase extraction disks are provided with one of the plurality of disks press fitted between the sidewalls of one of the plurality of changes proximate the bottom nozzle. Each disk comprises an extraction medium and silica gel in glass fibers.
The tapering sidewalls of the chamber provide a fritless means for receiving one of the plurality of solid phase extraction disks. Because no separate retaining rings, or frits, are required to support or maintain the solid phase extraction disks within the chambers, assembly of the solid phase extraction plate is greatly simplified.
More particularly, each of the chamber may have a circular cross section and, in addition, means may be provided for spacing each of the disks from a corresponding nozzle. The structure corresponding to this means for spacing includes a step formed in the sidewall of the chamber proximate the corresponding nozzle. Importantly, this structure also provides means for enabling fluid flow through each of the disks over a diameter of the disk which is greater than the diameter of a nozzle entry port. In this manner, efficient use of each disk is enabled by providing exposed areas on each side of the disk to facilitate fluid flow therethrough. This should be contrasted with prior art devices in which large portion of the extraction medium is masked by abutment with supporting structure.
While each of the chambers may have differing cross sections or diameter, it is preferable that each of the chambers be identical in order to facilitate assembly of the extraction disks therein.
More particularly, each of the disks may comprise a non-polar medium, polar medium, cation exchange medium, or an anion exchange medium. All of the disks may be of the same medium or different mediums. Still more particularly, the disks may comprise a combination of mediums, for example, both a non-polar/strong cation medium and a polar/strong cation medium.


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patent: 5417923 (1995-05-01), Bojanic et al.
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