Electrochemical Detection of Silica Species

• US 20100193377A1
• Filed: 06/29/2007
• Published: 08/05/2010
• Est. Priority Date: 06/29/2007
• Status: Active Grant

• Current Assignee: EMD Millipore Corporation (Merck & Co., Inc.), Arizona Board of Regents (University of Arizona)
• Original Assignee: EMD Millipore Corporation (Merck & Co., Inc.)
• Inventors: Le Ninivin, Celine, Dimitrakopoulos, Aristotelis, Wang, Joseph, Mabic, Stephane
• Granted Patent: US 8,702,957 B2
• Time in Patent Office: Days
• US Class Current: 205/782
• CPC Class Codes: G01N 27/48 using polarography, i.e. measuring changes in current under a slowly-varying voltage

Abstract

A systems and apparatus for measuring non-electroactive materials in liquids using electrochemical detection. A first electrical activity of a electroactive material is detected in absence of a target non-electroactive material (Step 120). A second electrical activity of the electroactive material is detected in presence of the target non-electroactive material (Step 130). A difference between the first and second electrical activities is obtained, and based on the obtained difference, a concentration of the target non-electroactive material is identified (Step 140).

Claims

1. A method comprising:

applying a voltage to a buffering solution, which comprises a metal complex and is free of inorganic species to be detected;

measuring a first current associated with the metal complex in absence of the inorganic species;

adding the inorganic species into the buffering solution;

measuring a second current associated with the metal complex in the presence of the added inorganic species; and

obtaining a difference between the first current and the second current to identify a concentration of the added inorganic species in the buffering solution.

2. The method of claim 1, wherein measuring the first and second currents comprises applying an accumulation potential followed by a scanning potential.

3. The method of claim 2, wherein the applying an accumulation potential comprises applying an accumulation potential of a amplitude comprising 0.5 volts.

4. The method of claim 2, wherein the applying an accumulation potential comprises applying an accumulation potential for a time period that includes 60 seconds.

5. The method of claim 2, wherein applying a scanning potential comprises applying a scanning potential having at least one of a 25 millivolt amplitude, a step potential of 4 millivolt, and a frequency of 25 hertz.

6. The method of claim 1, wherein applying a voltage includes applying a voltage to a buffering solution that includes a metal complex comprising a molybdenum-chloranilate complex.

7. The method of claim 1, wherein measuring the first and second currents comprises using a working electrode comprising at least one of bismuth, gold, carbon or mercury.

8. The method of claim 7, wherein measuring the first and second currents using a working electrode comprises using a screen printed electrode.

9. The method of claim 1, wherein adding inorganic species comprises adding silica species.

10. The method of claim 1, wherein measuring the first and second currents comprises measuring voltammetric signals.

11. The method of claim 10, wherein measuring the voltammetric signals comprises using a stripping voltammeter.

12. The method of claim 11, wherein measuring the voltammetric signals using a stripping voltammeter comprises using a disposable stripping voltammeter.

13. A system comprising:

a detection device comprising

a container configured to at least partially hold a solution in the container, the solution comprising a metal complex; and

an electrically conductive member that is at least partially submerged in the solution, wherein the container, the solution and the electrically conductive member are configured to measure a first current corresponding to the metal complex in absences of inorganic species and a second current corresponding the metal complex in the presence of inorganic species; and

a data processing device configured to

receive the measured first and second currents from the detection device; and

obtain a difference between the first current and the second current to identify a concentration of the inorganic species.

14. The system of claim 13 wherein the detection device is configured to measure the first and second currents corresponding to a metal complex comprising a molybdenum-chloranilate complex.

15. The system of claim 13, wherein the detection device is configured to measure the second current corresponding to the metal complex in presence of inorganic species comprising silica species.

16. The system of claim 13, wherein the electrically conductive member comprises at least one of bismuth, gold, carbon or mercury.

17. The system of claim 13, wherein the electrically conductive member comprises a screen printed electrode.

18. The system of claim 13, wherein the detection device is configured as a stripping voltammeter.

19. The system of claim 18, wherein the stripping voltammeter comprises a disposable stripping voltammeter.

20. The system of claim 13, wherein the detection device is configured to measure the first and second currents by applying an accumulation potential followed by a scanning potential.

21. A method comprising:

detecting a first electrical activity of an electroactive material in absence of a target non-electroactive material;

detecting a second electrical activity of the electroactive material in presence of the target non-electroactive material;

obtaining a difference between the first and second electrical activities; and

identifying a concentration of the target non-electroactive material based on the obtained difference.

22. The method of claim 21, wherein detecting the first and second electrical activities comprises applying an accumulation potential followed by a scanning potential.

23. The method of claim 21, wherein the detecting the first and second electrical activities comprises detecting the first and second electrical activities of a metal complex in a buffering solution.

24. The method of claim 21, wherein the identifying a concentration of the target non-electroactive material comprises identifying a concentration of a target silica species.