Indicator and method for manufacturing the same

• US 3,232,710 A
• Filed: 03/05/1963
• Issued: 02/01/1966
• Est. Priority Date: 01/28/1951
• Status: Expired due to Term

• Current Assignee: Erich Haack, Hans-Georg Rey, Peter Rieckmann
• Original Assignee: Erich Haack, Hans-Georg Rey, Peter Rieckmann
• Inventors: PETER RIECKMANN, HANS-GEORG REY, Haack, Erich
• Application Number:
  US04/262,827
• Time in Patent Office: 1,064 Days
• US Class Current: 435/25
• CPC Class Codes: C12Q 1/26 involving oxidoreductase
• CPC Class Codes: C12Q 1/28 involving peroxidase
• CPC Class Codes: C12Q 1/54 involving glucose or galactose
• CPC Class Codes: C12Q 2326/14 Ortho-Tolidine, i.e. 3,3'-dimethyl-(1,1'-biphenyl-4,4'-diamine)
• CPC Class Codes: C12Q 2326/40 Triphenylmethane dye chromogens, e.g. fluorescein derivatives
• CPC Class Codes: G01N 31/22 using chemical indicators G01N31/02 takes precedence
• CPC Class Codes: G01N 33/521 Single-layer analytical elements
• CPC Class Codes: G01N 33/523 the element being adapted for a specific analyte
• CPC Class Codes: Y10S 435/805 Test papers
• CPC Class Codes: Y10T 436/144444 Glucose
• CPC Class Codes: Y10T 436/173076 Nitrite or nitrate
• CPC Class Codes: Y10T 436/178459 Only nitrogen dioxide

Claims

1. ANALYTICAL INDICATOR CHARACTERIZED BY PROLONGED SHELF LIFE COMPRISING A SUBSTANTIALLY PLANE PAPER SHEET HAVING A WETTABLE SURFACE IMPREGNATED WITH A REAGENT FOR PRODUCING A CONTRASTING COLOR WITH RESPECT TO SAID PAPER SHEET ON SPREADING OF A LIQUID CONTAINING THE SUBSTANCE OF INTEREST THEREOVER AS VISUAL EVIDENCE OF THE PRESENCE OF SAID SUBSTANCE OF INTEREST IN SAID LIQUID, SAID INDICATOR INCLUDING SUPER-POSED UPPER AND LOWER LAYERS OF A WATER-INSOLUBLE PLASTIC MATERIAL, WITH THE PAPER SHEET THEREBETWEEN, SAID UPPER AND LOWER PLASTIC LAYERS OVERLYING, RESPECTIVELY, SUBSTANTIALLY THE ENTIRE UPPER AND LOWER SURFACES OF THE PAPER, SAID PLASTIC LAYERS EXTENDING BEYOND TWO OPPOSITE EDGE PORTIONS OF THE TEST PAPER AND BEING JOINED ALONG THE EDGES THEREOF DISPOSED OUTWARDLY OF THE STRIP FORMING A CLOSE-FITTING CLOSURE ABOUT THE TEST PAPER, AT LEAST ONE END OF THE CLOSURE BEING OPEN,