Methods and apparatus for determining analytes in various matrices
Methods and apparatus for qualitatively or quantitatively determining one or more analytes in matrices such as foods, biological fluids, etc. An embodiment for determination of a single analyte comprises a sample receiving vessel, a first membrane and a reagent-containing well. The prepared sample passes through the first membrane whereby extraneous matter is removed, and a filtrate enters the reagent-containing well to provide a filtrate-reagent admixture from which the analyte may be determined. An embodiment for determination for multiple analytes includes one or more additional membranes in series with the first membrane, each such additional membrane being operative to capture one or more analytes. Each of the additional analytes may then be eluted from the membrane upon which it has been captured, into a separate reagent-containing well to provide eluant-reagent admixture from which each desired analyte may be determined. Formulations for preparation additives are also included. Additionally, there's provided an embodiment of above-described invention for determination of an analyte which is present in a matrix at low (e.g., sub-detectable) levels, wherein the filter of the apparatus is utilized to capture and concentrate the analyte, to provide a filtrate-reagent admixture wherein the analyte is present at detectable concentration.
1. An apparatus for non-electrophoretic determination of the presence of at least one analyte in at least one flowable sample, said apparatus comprising:
a housing having a cavity formed therein;
at least one filtrate-receiving vessel positioned within the cavity of the housing, the filtrate-receiving vessel having an open end;
at least one membrane module positioned over the open end of the at least one filtrate-receiving vessel, the at least one membrane module having portions formed of a first hard material and portions formed of a second elastomeric material;
at least one sample-receiving well, each sample-receiving well being positioned in association with one of said membrane components such that sample place within a particular sample receiving well is filtered through the associated membrane module, and a filtrate which emerges from that membrane module will be received within the associated filtrate-receiving vessel;
a cover for sealing said cavity of said housing, the cover having at least one sample port bounded by a rim_extending from the surface of the lid away from the cavity, wherein the rim is structured to retain the at least one membrane module such that the portions of the at least one membrane module that are formed of elastomeric material interact with the rim to provide substantially air tight sealing between the membrane module and the rim; and
a differential pressure source to cause a pressure differential between each of said sample-receiving wells and each of said filtrate-receiving vessels, said pressure differential being operative to drive each sample through the associated membrane module and the resultant filtrate into the associated filtrate-receiving vessel.
2. The apparatus of claim 1 wherein said pressure source provides negative pressure within the cavity of said, housing so as to pull the filtrate through each membrane component.
3. The apparatus of claim 1 wherein said pressure source provides positive pressure within the samples wells so as to push the filtrate through each membrane component.
4. The apparatus of claim 2 further comprising:
at least one air-inlet opening formed in said apparatus, the air inlet openings being associated with each one of said sample-receiving wells, such that when a particular sample-receiving well becomes empty air will be drawn through the associated air inlet opening.
5. The apparatus of claim 1 wherein the differential pressure source comprises a pump which is integral of the apparatus.
6. The apparatus of claim 5 wherein said pump integral of the apparatus is a vacuum pump which is incorporated within said housing.
7. The apparatus according to claim 1 wherein the at least one membrane module comprises a plurality of membrane modules, and at least two of the membrane modules are configured so as to nest within one another when stacked, thereby ensuring proper alignment of the membrane to allow sample to flow through each sample flow channel.