Methods and apparatus for determining specific analytes in foods and other complex matrices

• US 6,489,132 B1
• Filed: 09/02/1999
• Issued: 12/03/2002
• Est. Priority Date: 10/02/1996
• Status: Expired due to Fees

• Current Assignee: Saftest, Inc.
• Original Assignee: Safety Associates, Inc.
• Inventors: Sorensen, John T., Elias, John F., Gordon, Virginia C., Mirhashemi, Soheila, Mittelstein, Michael
• Primary Examiner(s): Le, Long V.
• Assistant Examiner(s): Padmanabhan, Kartic
• Application Number:
  US09/388,974
• Time in Patent Office: 1,188 Days
• Field of Search: 210/200, 210/201, 210/203, 210/238, 210/252, 210/253, 210/255, 210/263, 210/290, 210/295, 210/301, 210/322, 210/314, 210/323.1, 210/348, 210/500.29, 210/600, 210/634, 210/649, 210/767, 210/800, 210/806, 210/908, 422/56, 422/58, 422/60, 422/68.1, 422/82, 422/102, 422/147, 422/188, 422/190, 422/211, 422/213, 422/216, 422/236, 422/239, 422/240, 422/101, 435/7.92, 435/179, 435/180, 435/7.1, 436/175, 436/177, 436/178, 436/518, 436/527, 436/530, 436/824, 436/825
• US Class Current: 435/7.92
• CPC Class Codes: G01N 33/52 Use of compounds or compositions for colorimetric, spectrophotometric or fluorometric investigation, e.g. use of reagent paper and including single- and multilayer analytical elements immunological elements G01N33/54386; involving labelled immunochemicals G01N33/58; for haemoglobin or occult blood G01N33/72
• CPC Class Codes: G01N 33/54366 Apparatus specially adapted for solid-phase testing
• CPC Class Codes: Y10S 210/908 Organic
• CPC Class Codes: Y10S 436/824 Immunological separation techniques
• CPC Class Codes: Y10S 436/825 Pretreatment for removal of interfering factors from sample
• CPC Class Codes: Y10T 436/25125 Digestion or removing interfering materials
• CPC Class Codes: Y10T 436/25375 Liberation or purification of sample or separation of material from a sample [e.g., filtering, centrifuging, etc.]
• CPC Class Codes: Y10T 436/255 including use of a solid sorbent, semipermeable membrane, or liquid extraction

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. 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 a detectable concentration.

Claims

1. A method for determining a presence of a plurality, n, of analytes within a matrix, said method comprising the steps of:

a) providing a plurality, n, of membranes;

b) passing the matrix through a first membrane to remove extraneous matter therefrom, such that a filtrate containing said analytes will pass through the first membrane;

c) passing the filtrate through n−

1 additional membranes such that each of said additional membranes captures one of said n analytes, and such that a sub-filtrate containing the remaining analyte will pass through all of said n−

1 membranes;

d) collecting the sub-filtrate which has passed through said first membrane and said n−

1 additional membranes, and combining said sub-filtrate with at least one reagent to provide a sub-filtrate reagent admixture from which a presence of said remaining analyte may be determined;

e) eluting each of said analytes captured by said n−

1 additional membranes from each of said additional membranes, and combining each of such eluants with at least one reagent to provide an eluant-reagent admixture from which a presence analyte may be determined;

f) determining a presence of said remaining analyte in said sub-filtrate-reagent admixture; and

g) determining a presence of the analytes in the eluant-reagent admixtures.

2. A method for determination of lipid peroxides, malonaldehyde and histamine within a matrix, said method comprising the steps of:

a) passing the matrix through a microporous first membrane which will remove extraneous matter while allowing a filtrate comprising lipid peroxides, malonaldehyde and histamine to pass therethrough;

b) passing the filtrate through a second membrane formed of DEAE cellulose to capture malonaldehyde, and a third membrane formed of silica glass to capture lipid peroxides, such that a sub-filtrate containing histamine will pass through all three of said membranes;

c) collecting the sub-filtrate containing histamine, and combining said sub-filtrate with a mixture of histaminase and peroxidase to provide a filtrate-histaminase peroxidase admixture from which a concentration of histamine is determined by analysis of histamine-derived peroxide conjugates contained therein;

d) eluting the malonaldehyde captured by the DEAE cellulose membrane to produce a first eluant containing malonaldehyde, and combining the first eluant with methyl indole to provide a malonaldehyde-indole mixture from which a concentration of malonaldehyde is determined; and

e) eluting the lipid peroxide captured by the silica glass membrane to produce a second eluant containing lipid peroxide, and combining the second eluant with xylenol orange to provide a lipid peroxide-xylenol orange admixture from which a concentration of lipid peroxides is determined.

3. A method for determining sulfites, free aldehydes, and sulfite-bound aldehydes within a matrix, said method comprising the steps of:

a) passing the matrix through a microporous first membrane having pores of approximately 0.45 microns formed therein to remove extraneous matter while allowing a filtrate containing sulfites, free aldehydes, and sulfite-bound aldehydes to pass therethrough;

b) passing the filtrate through a second membrane formed of DEAE cellulose to capture sulfite and sulfite-bound aldehydes while allowing a sub-filtrate which contains free aldehydes to pass therethrough;

c) collecting the sub-filtrate containing free aldehydes and combining the sub-filtrate with methyl indole to provide a filtrate-methyl indole admixture from which a concentration of free aldehydes is determined;

d) eluting the sulfite and sulfite-bound aldehydes captured by the DEAE cellulose membrane to produce an eluant, and combining the eluant with sulfite oxidase at an alkaline pH to provide an eluant-sulfite oxidase admixture of alkaline pH, from which a concentration of sulfite-bound aldehydes is determined; and

e) acidifying the eluant-sulfite oxidase admixture to provide an eluant-sulfite oxidase admixture of acid pH, from which a concentration of non-aldehyde-bound sulfites is determined.

4. A method for determining malonaldehyde, lipid peroxides and xanthine within a matrix, said method comprising the steps of:

a) passing the matrix through a microporous first membrane having pores of approximately 0.45 microns formed therein to remove extraneous matter while allowing a filtrate containing malonaldehyde, lipid peroxides and xanthine to pass therethrough;

b) passing said filtrate through a second membrane formed of material which will capture lipid peroxides and a third membrane which is coated with xanthine oxidase for capturing xanthine while allowing a sub-filtrate containing malonaldehyde to pass therethrough;

c) collecting the sub-filtrate containing malonaldehyde, and combining said sub-filtrate with methyl indole to provide a sub-filtrate-methyl indole admixture from which a concentration of malonaldehyde is determined;

d) eluting the lipid peroxides captured by said second membrane to produce a first eluant containing lipid peroxides, and combining the first eluant with xanthine oxidase to provide a first eluant-xanthine oxidase admixture from which a concentration of lipid peroxides is determined; and

e) eluting the xanthine captured by said third membrane to produce a second eluant containing xanthine, and combining the second eluant with a peroxidase to provide a second eluant-peroxidase admixture from which a concentration of xanthine is determined.