Square wave amperometry alkalinity measurement

Patent metadata

Field	Value
Publication number	US-11808733-B2
Application number	US-202117143700-A
Country	US
Kind code	B2
Filing date	Jan 7, 2021
Priority date	Jan 7, 2021
Publication date	Nov 7, 2023
Grant date	Nov 7, 2023

Abstract

An embodiment provides a method for measuring an alkalinity of an aqueous sample, including: introducing an aqueous sample to a voltammetric pH electrode; holding the potential of a voltammetric pH electrode at a pH end point potential; applying a voltage step waveform comprising at least one potential pulse to the voltammetric pH electrode; titrating the aqueous sample; and measuring a current output resulting from the voltage step waveform, wherein the measuring comprises square wave amperometry. Other aspects are described and claimed.

First claim

What is claimed is:

1. A method for measuring an alkalinity of an aqueous sample, comprising:
introducing the aqueous sample to a voltammetric pH electrode;
holding a potential of the voltammetric pH electrode at a pH end point bias potential, wherein the pH end point bias potential corresponds to a titration pH end point;
applying a voltage step waveform comprising a plurality of potential pulses to the voltammetric pH electrode;
titrating the aqueous sample;
measuring one or a few current outputs resulting from the plurality of potential pulses, wherein the measuring comprises square wave amperometry; and
plotting a series current outputs from the voltage step waveform over a time span of the titrating to obtain a current maximum value.

2. The method of claim 1 , wherein the voltammetric pH electrode comprises a boron doped diamond material.

3. The method of claim 1 , wherein the voltage step waveform comprises pulsed potential steps.

4. The method of claim 1 , wherein the titrating comprises an addition of protons to the aqueous sample, wherein the addition of protons is selected from the group consisting of: in-situ generation and acid addition.

5. The method of claim 4 , wherein the addition of protons correlates to the alkalinity of the aqueous sample.

6. The method of claim 1 , wherein the measuring comprises a differential output current for each potential pulse between at least a portion of a forward step and at least a portion of a backward step.

7. The method of claim 1 , wherein the measuring further comprises a mode selected from the group consisting of: continuous measurement and intermittent measurement.

8. The method of claim 7 , wherein the mode correlates to the titrating.

9. The method of claim 1 , wherein the voltage step waveform comprises square wave potential perturbations applied to the voltammetric pH electrode to produce current responses which correlate to a pH redox response of the electrode.

Assignees

• Hach Co

Inventors

• Salzer Corey Alan

Classifications

• G01N27/4167 Primary

  pH (electrodes therefor G01N27/302, G01N27/36) · CPC title

• G01N27/49 Primary

  Systems involving the determination of the current at a single specific value, or small range of values, of applied voltage for producing selective measurement of one or more particular ionic species · CPC title

• G01N27/308

  at least partially made of carbon · CPC title

• G01N27/44

  using electrolysis to generate a reagent, e.g. for titration · CPC title

• G01N31/16

  using titration · CPC title