Apparatus for urea analysis

• US 4,614,577 A
• Filed: 12/27/1984
• Issued: 09/30/1986
• Est. Priority Date: 07/29/1981
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Gebhardt, Ulrich, Mund, Konrad, Luft, Gunter
• Primary Examiner(s): Tung, T.
• Application Number:
  US06/686,837
• Time in Patent Office: 642 Days
• Field of Search: 204/1 T, 204/1 E, 204/403, 204/415
• US Class Current: 204/403.06
• CPC Class Codes: G01N 33/5304 Reaction vessels, e.g. agglutination plates for solid-phase systems G01N33/543
• CPC Class Codes: G01N 33/62 involving urea

Abstract

For determining the urea concentration in liquids in continuous operation, with a high sensitivity and reliable determination of the urea content over an extended period of time, an electrode which is separated from the urea containing liquid by means of a diaphragm with a diffusion coefficient of less than 10^-7 cm² s^-1 for urea has impressed on it potentiostatically and cyclically, two potential values, the more positive potential being between 0.9 and 2.0. V/H₂ rev, and the more negative potential being lower than 0.6 V/H₂ rev, and at the more positive potential, the current flowing within a predetermined time interval is evaluated as the measuring signal.

Claims

1. A urea sensor comprising:

(a) a measuring electrode,

(b) a counter electrode and a reference electrode,

(c) a diaphragm with a diffusion coefficient for urea of less than 10^-7 cm² s^-1 covering the measuring electrode, whereby during use said diaphram will be disposed between said measuring electrode and a urea containing liquid, said diaphragm having both hydrophobic and hydrophilic properties and having a degree of hydrophilization, H, which is in the interval of from about 1;

15 to about 1;

100.

2. A urea sensor according to claim 1, wherein said diaphragm has a diffusion coefficient for urea of about 10^-11 cm² s^-1.

3. A urea sensor according to claim 1 or 2, wherein said diaphragm has a thickness of ≦

10 μ

m.

4. A urea sensor according to claim 1, wherein the degree of hydrophilization H of the diaphragm is in the interval 1:

30≧

H≧

1;

60.

5. A urea sensor according to claim 1 or 4, wherein said diaphragm consists of weakly hydrophilized polysulfone, and preferably sulfonized polysulfone.

6. A urea sensor according to claim 1, wherein said measuring electrode consists of a noble metal, preferably of platinum.

7. A urea sensor according to claim 1, wherein said counter electrode at the same time acts as the reference electrode.

8. A urea sensor according to claim 7, wherein said counter electrode consists of vitreous carbon.