Measurement of total organic carbon

Patent metadata

Field	Value
Publication number	US-9791430-B2
Application number	US-201514721960-A
Country	US
Kind code	B2
Filing date	May 26, 2015
Priority date	May 23, 2014
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

A method for determining the total organic carbon in a sample which includes mixing the sample with a reagent containing at least one acid effective for reacting with inorganic carbon-containing materials in the sample, and at least one oxidizing agent effective for oxidizing organic carbon-containing materials in the sample in the presence of ultraviolet radiation, and detecting the carbon dioxide generated, is described. The at least one acid may include phosphoric acid, while the oxidizing agent may include sodium persulfate. In accordance with an embodiment of the inventive concept, the sample is first injected into a reaction chamber, which is continuously flushed with carbon dioxide free gas with no UV light present, and CO 2 generated from any inorganic carbon in the sample as carbonates is flowed through the detector, and may be recorded. Subsequent to this step, the UV light is passed through the reaction chamber and CO 2 generated from the reaction of the at least one oxidizing agent with the organic material in the solution in the presence of ultraviolet radiation, is flowed through the detector, which may be a non-dispersive infrared detector, after the reaction chamber is sparged using a carbon dioxide free gas, and recorded.

First claim

What is claimed is:

1. A method for measuring total organic carbon in a sample, comprising: in a reaction chamber, mixing the sample with a reagent comprising an aqueous solution of both at least one acid effective for acidifying the sample-reagent solution formed thereby to a chosen pH value, whereby carbon dioxide from inorganic sources of carbon in the solution is generated, and at least one oxidizer effective for converting organic carbon into carbon dioxide only in the presence of ultraviolet radiation; sparging the resulting solution with a carbon dioxide free gas to remove carbon dioxide generated from inorganic carbon from the solution; irradiating the solution in the reaction chamber with ultraviolet light having a wavelength such that the at least one oxidizer converts organic carbon into carbon dioxide; sparging the resulting solution with a carbon dioxide free gas to remove carbon dioxide from organic carbon in the sample from the solution; and measuring the carbon dioxide removed from the solution by the second sparging step; whereby the total organic carbon in the solution is determined.

2. The method of claim 1 , wherein the carbon dioxide is measured using non-dispersive infrared detection having a range of detection for carbon dioxide.

3. The method of claim 2 , further comprising the step of removing water from the carbon dioxide before said step of measuring the carbon dioxide.

4. The method of claim 2 , further comprising the step of diluting the sample using the reagent if the carbon dioxide generated from the sample is greater than the range for carbon dioxide detection.

5. The method of claim 1 , further comprising the step of measuring the carbon dioxide removed from the solution by said step of sparging before said step of irradiating the solution, whereby total inorganic carbon may be determined.

6. The method of claim 5 , further comprising the step of removing water from the carbon dioxide before said step of measuring the carbon dioxide.

7. The method of claim 6 , wherein the carbon dioxide is measured using non-dispersive infrared detection.

8. The method of claim 6 , wherein total carbon is determined as the sum of the total inorganic carbon and the total organic carbon in the sample.

9. The method of claim 1 , wherein the acid comprises at least one inorganic acid.

10. The method of claim 9 , wherein the at least one inorganic acid is chosen from phosphoric acid, hydrochloric acid, nitric acid, and sulfuric acid, and mixtures thereof.

11. The method of claim 1 , wherein the at least one oxidizer comprises a persulfate.

12. The method of claim 11 , wherein the persulfate is chosen from sodium persulfate and potassium persulfate.

13. The method of claim 1 , wherein the carbon dioxide free gas is chosen from oxygen and nitrogen.

14. The method of claim 1 , wherein the step of irradiating the solution is undertaken for less than or equal to about 5 min., followed by the step of sparging the irradiated solution.

15. The method of claim 1 , wherein the step of irradiating the solution is performed using an irradiation source chosen from a mercury vapor lamp, and an ultraviolet light emitting diode.

16. The method of claim 1 , wherein the chosen pH value is less than about 4.

17. The method of claim 1 , wherein the reagent comprises about 0.01 molar phosphoric acid and about 0.01 molar persulfate in water.

Assignees

• Hach Co

Inventors

• Hammerschmidt Ramon

Classifications

• Y10T436/204998

  Inorganic carbon compounds · CPC title

• Y10T436/235

  In an aqueous solution [e.g., TOC, etc.] · CPC title

• G01N21/3504

  for analysing gases, e.g. multi-gas analysis · CPC title

• G01N21/75

  Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated (systems in which material is burnt in a flame or plasma G01N21/72, G01N21/73) · CPC title

• G01N21/272

  for following a reaction, e.g. for determining photometrically a reaction rate (photometric cinetic analysis) · CPC title