Abstract: 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.

Abstract: Methods and systems for determining the presence of one or more analytes in various types of matricies, such as foods, oils, biological fluids, etc. Membranes are used to remove extraneous matter (e.g., solid particles) and/or to bind specific interferents or analytes. Specific assays are provided for determining citric acid, total fat (or % fat), free fatty acids, protein content and specific nucleic acid content indicative of the presence of DNA and/or RNA of certain microbes (e.g., pathogens) or genetically altered substances (e.g., genetically engineered grain).