Dry reagent for creatinine assay

• US 5,464,777 A
• Filed: 09/26/1994
• Issued: 11/07/1995
• Est. Priority Date: 09/26/1994
• Status: Expired due to Term

• Current Assignee: Siemens Healthcare Diagnostics Incorporated (Siemens AG)
• Original Assignee: Miles, Inc. (Bayer AG)
• Inventors: Yip, Kin-Fai
• Primary Examiner(s): Housel, James C.
• Assistant Examiner(s): McGlashen, Michael L.
• Application Number:
  US08/312,559
• Time in Patent Office: 407 Days
• Field of Search: 436/98, 436/106, 436/909, 436/534, 436/518, 435/7.1, 435/973, 435/962
• US Class Current: 436/98
• CPC Class Codes: G01N 33/70 involving creatine or creatinine
• CPC Class Codes: Y10S 435/973 Simultaneous determination of more than one analyte
• CPC Class Codes: Y10T 436/147777 Plural nitrogen in the same ring [e.g., barbituates, creatinine, etc.]

Abstract

A method for the determination of protein and creatinine in urine. An organic acid, in the form of its lithium salt, is dried onto a suitable substrate in the second reaction zone of a reaction vessel having a first reaction zone for the immunometric determination of the protein and a second reaction zone for the colorimetric determination of creatinine. After completion of the immunometric determination of the protein the dried organic salt is contacted with the urine containing creatinine resulting in solubilization of the organic acid salt as creatinine reactive reagent thereby facilitating the colorimetric determination of the creatinine.

Claims

1. An assay for a urinary protein and creatinine which comprises the steps of:

a) providing a reaction vessel having a substantially horizontal axis of rotation and an analytical reaction channel containing first and second reaction zones, the second reaction zone situated a predetermined distance from and in fluid communication with the first reaction zone whereby a liquid test sample disposed in the reaction channel is capable of being transported by gravity along the reaction channel between the reaction zones by rotating the reaction vessel along its axis of rotation;

delivery means for providing a unidirectional flow of a liquid test sample into the reaction vessel and inlet means in liquid communication with the delivery means for introducing the liquid test sample into the delivery means, the first reaction zone having an antibody reagent dried therein and the second reaction zone containing a dried lithium salt of an organic acid capable of reacting with creatinine under alkaline conditions in which the pH is from about 11.5 to 12.5 to form a colored reaction product therewith and a dried alkaline material which upon rehydration is capable of providing the necessary alkalinity for the creatine/organic acid reaction, said reaction vessel also having a viewing port between the first and second reaction zones;

b) introducing urine suspected of containing protein and creatinine as the liquid test sample into the reaction vessel through the delivery means and also introducing a reaction fluid containing a polymeric agglutinator which specifically binds with the antibody reagent dried in the first reaction zone to thereby solubilize the antibody reagent and cause an agglutination reaction which is quantified by the taking of readings through the viewing port;

c) rotating the reaction vessel about its axis of rotation to bring the liquid test sample/reaction fluid combination into contact with the lithium salt of the organic acid and alkaline material thereby causing their dissolution and raising the pH to a level of from about 11.5 to 12.5 and resulting in a colored response between the organic acid anion and any creatinine present in the liquid test sample and determining the magnitude of this colored response as a function of the creatinine in the urine sample.

2. The assay of claim 1 wherein the organic acid is 3,5-dinitrobenzoic acid, picric acid or 1,4-napthoquinone-2-sulfonic acid.

3. The assay of claim 2 wherein the organic acid is 3,5-dinitrobenzoic acid.

4. The assay of claim 1 wherein the alkaline material is an alkali metal hydroxide.

5. The assay of claim 4 wherein the alkali metal hydroxide is potassium, sodium or lithium hydroxide.

6. The assay of claim 1 wherein the magnitude of the colored response is determined by taking a spectrophotometric reading through the viewing port and comparing the results of this reading with readings taken on urine samples containing known concentrations of creatinine.