Method of measuring hydroquinone levels in boiler feedwaters using electrochemistry

• US 5,104,809 A
• Filed: 02/06/1991
• Issued: 04/14/1992
• Est. Priority Date: 02/06/1991
• Status: Expired due to Fees

• Current Assignee: Betz Laboratories, Inc. (General Electric Company)
• Original Assignee: Betz Laboratories, Inc. (General Electric Company)
• Inventors: Moulton, Roger D.
• Primary Examiner(s): Rollins, John W.
• Application Number:
  US07/651,159
• Time in Patent Office: 433 Days
• Field of Search: 436/96, 422/53, 422/13, 422/16
• US Class Current: 436/96
• CPC Class Codes: G01N 33/1826 Organic contamination in water
• CPC Class Codes: Y10T 436/145555 Hetero-N

Abstract

An improved method of electroanalytical detection of residual hydroquinone in boiler feedwater employing adding an ionic base and a copper chelant to the feedwater sample. Na₃ PO₄ and ethylenediamine are representative chemicals when square wave voltammetry (SWV) is used as the electroanalytical technique.

Claims

1. A method of measuring the amount of residual hydroquinone in boiler feedwaters of the type containing copper employing an electroanalytical technique, the improvement comprising adding to said boiler feedwaters an effective amount for the purpose of an ionic base which maintains the pH of said boiler feedwaters in a range of 9 to 11 and increases the ionic conductivity of said boiler feedwaters and a copper chelant which complexes with the copper present in said boiler feedwaters and thereby employing an electroanalytical technique to measure the concentration of residual hydroquinone.

2. A method according to claim 1 wherein said electroanalytical technique is square-wave voltammetry.

3. A method according to claim 1 wherein said ionic base is Na₃ PO₄.

4. A method according to claim 3 wherein said Na₃ PO₄ is added to said boiler feedwaters in a range of about 1 mM to about 1M concentration.

5. A method according to claim 1 wherein said copper chelant is ethylenediamine.

6. A method according to claim 5 wherein said copper chelant is added to said boiler feedwaters in excess of demand at a ratio up to 100 to 1.

7. A method according to claim 2 wherein said square wave voltammetry is performed on said boiler feedwaters at -0.1 V vs SCE.