Anodic stripping voltammetry system and combination electrode assembly therefore

• US 4,058,446 A
• Filed: 11/29/1976
• Issued: 11/15/1977
• Est. Priority Date: 11/29/1976
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Clavell, Cesar, Huey, Kent, Zirino, Alberto
• Primary Examiner(s): Kaplan, G. L.
• Application Number:
  US05/745,931
• Time in Patent Office: 351 Days
• Field of Search: 204/1 T, 204/1 M, 204/195 T, 204/195 H, 204/195 R, 204/272
• US Class Current: 204/409
• CPC Class Codes: G01N 27/42 Measuring deposition or liberation of materials from an electrolyte; Coulometry, i.e. measuring coulomb-equivalent of material in an electrolyte

Abstract

An improvement for an anodic stripping voltammetry system for measuring theresence and concentration of trace metals in a seawater solution yields more representative readings. A combination electrode is fashioned from a porous polyethylene cylinder having a coaxial bore for receiving the flowing solution. A helically extending silver/silver chloride reference electrode is disposed on the outside of the cylinder and a platinum counter electrode is located in its bore. The porous polyethylene prevents chlorides from contaminating the reference electrode while the counter electrode drains off currents. Thus, more representative potential readings between a working electrode and the reference electrode are made as trace metals are stripped away into the circulating solution.

Claims

1. In an anodic stripping voltammetry system for measuring the presence and concentration of trace metals in a sample solution having a source of a metal plating solution, a means for sensing trace metals, a means for feeding the sample solution and the plating solution through the sensing means, a means coupled for alternately coupling the sample solution and the plating solution to the sensing means, a means for depositing a metal plating film on the sensing means while the plating solution is coupled to flow through the sensing means and for reducing trace metals on the metal plating film while the sample solution is alternately coupled to flow through the sensing means, and means for indicating the presence and concentration of trace metals in the sample solution, an improvement therefor is provided comprising:

a combination electrode including a tubularly shaped body member provided with a coaxial bore coupled to receive the flow of the plating solution and the sample solution, a reference electrode disposed on the outer surface of the body member, and a counter electrode disposed in the bore of the body member and reaching to the exterior of the body member both electrodes extending to the indicating means.

2. An improvement according to claim 1 wherein the tubularly shaped body member is fashioned from a porous polyethylene tube impregnated with a potassium chloride saturated agar solution and the reference electrode is a helically extending length of anodized wire covered wih silver chloride.

3. An improvement according to claim 2 further including:

a section of heat shrink tubing extending to contain the tubularly shaped body member and to hold the helically extending length of anodized wire against the outer surface of the body member.

4. An improvement according to claim 3 in which the counter electrode is platinum gauze disposed in the coaxial bore coupled to a platinum foil strip reaching to the exterior of the body member.

5. An improvement according to claim 4 further including:

an epoxy seal potting the tubularly shaped body member, the helically extending length of anodized wire and the heat shrink tubing therein.

6. A combination electrode for receiving a flowing solution therethrough comprising:

a tubularly shaped body member fashioned from a porous polyethylene tube impregnated with a potassium chloride saturated agar solution and provided with a coaxial bore coupled to receive the flowing solution;

a reference electrode in the form of a helically extending length of anodized wire covered with silver chloride disposed on the outer surface of the body member and

a counter electrode disposed in the coaxial bore of the body member and reaching to the exterior of the body member.

7. A combination electrode according to claim 6 further including:

a section of heat shrink tubing extending to contain the tubularly shaped body member and to hold the helically extending length of anodized wire against the outer surface of the body member.

8. A combination electrode according to claim 7 in which the counter electrode is platinum gauze disposed in the coaxial bore coupled to a platinum foil strip reaching to the exterior of the body member.

9. A combination electrode according to claim 8 further including:

an epoxy seal potting the tubularly shaped body member, the helically extending length of annodized wire and the heat shrink tubing therein.