Methods for measuring concentrations of chlorinated solvents through raman spectroscopic observation of the vibrational modes of water

Patent metadata

Field	Value
Publication number	US-9488582-B2
Application number	US-201514656136-A
Country	US
Kind code	B2
Filing date	Mar 12, 2015
Priority date	Mar 14, 2014
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

Abstract

Method for determining concentration of a chlorinated solvent in a non-turbid aqueous solution sample containing the chlorinated solvent is disclosed. The method includes developing a calibration profile relating intensities of Raman returns at a predetermined Raman shift associated with O—H stretching region of water for non-turbid aqueous chlorinated solvent calibration solutions of known concentrations. Intensity of Raman return at the predetermined Raman shift associated with O—H stretching region of the non-turbid aqueous solution sample is measured and compared to the calibration profile to determine the concentration of the chlorinated solvent in the non-turbid aqueous solution sample. For turbid solution samples, a method using turbidity-corrected intensity for the solution sample is disclosed. Alternatively, for turbid solution samples, a method employing a calibration profile utilizing turbid calibration solutions is disclosed.

First claim

The invention claimed is:

1. A method comprising:
providing a plurality of non-turbid aqueous chlorinated solvent calibration solutions, the calibration solutions comprising solutions of water and a chlorinated solvent, each calibration solution having a concentration of the chlorinated solvent within a predetermined concentration range, at least two of the chlorinated solvent calibration solutions having different concentrations of the chlorinated solvent within the predetermined concentration range;
measuring intensity of Raman return at a predetermined Raman shift associated with O—H stretching region of water for each of the plurality of non-turbid aqueous chlorinated solvent calibration solutions;
developing a calibration profile for non-turbid solutions relating chlorinated solvent concentrations of the plurality of the non-turbid aqueous chlorinated solvent calibration solutions to the measured intensities;
obtaining a non-turbid aqueous solution sample whose chlorinated solvent concentration has to be determined, the sample containing the chlorinated solvent;
measuring intensity of Raman return at the predetermined Raman shift associated with O—H stretching region of the non-turbid aqueous solution sample;
comparing the intensity of Raman return at the predetermined Raman shift associated with O—H stretching region of the non-turbid aqueous solution sample to the calibration profile for non-turbid solutions; and
determining the concentration of the chlorinated solvent in the non-turbid aqueous solution sample.

2. The method of claim 1 , wherein the predetermined concentration range includes zero concentration.

3. The method of claim 1 , wherein the non-turbid aqueous solution sample whose chlorinated solvent concentration has to be determined is taken from a geographic region of interest.

4. The method of claim 3 , wherein the geographic region of interest is a well, a body of water, a subsurface water environment, an aquifer, a waste water stream, or an industrial process stream.

5. The method of claim 3 , wherein the chlorinated solvent is trichloroethylene.

6. The method of claim 3 , wherein the chlorinated solvent is an aggregate of chlorinated solvents.

7. The method of claim 1 , wherein the chlorinated solvent is trichloroethylene.

8. The method of claim 1 , wherein the chlorinated solvent is an aggregate of chlorinated solvents.

9. A method comprising:
providing a plurality of non-turbid aqueous chlorinated solvent calibration solutions, the calibration solutions comprising solutions of water and a chlorinated solvent, each calibration solution having a concentration of the chlorinated solvent within a predetermined concentration range, at least two of the chlorinated solvent calibration solutions having different concentrations of the chlorinated solvent within the predetermined concentration range;
measuring intensity of Raman return at a predetermined Raman shift associated with O—H stretching region of water for each of the plurality of non-turbid aqueous chlorinated solvent calibration solutions;
developing a calibration profile for non-turbid solutions relating concentrations of the plurality of the non-turbid aqueous chlorinated solvent calibration solutions to the measured intensities;
obtaining a turbid aqueous solution sample whose chlorinated solvent concentration has to be determined, the sample containing the chlorinated solvent;
measuring intensity of Raman return at the predetermined Raman shift associated with O—H stretching region of the turbid aqueous solution sample;
applying a turbidity correction to the measured of Raman return at the predetermined Raman shift associated with O—H stretching region of the turbid aqueous solution sample to obtain a turbidity-corrected intensity; and
comparing the turbidity-corrected intensity to the calibration profile for non-turbid solutions; and
determining concentration of the chlorinated solvent in the turbid aqueous solution sample.

10. The method of claim 9 , wherein the predetermined concentration range includes zero concentration.

11. The method of claim 9 , wherein the turbid aqueous solution sample whose chlorinated solvent concentration has to be determined is taken from a geographic region of interest.

12. The method of claim 11 , wherein the geographic region of interest is a well, a body of water, a subsurface water environment, an aquifer, a waste water stream, or an industrial process stream.

13. The method of claim 11 , wherein the chlorinated solvent is trichloroethylene.

14. The method of claim 11 , wherein the chlorinated solvent is an aggregate of chlorinated solvents.

15. The method of claim 9 , wherein the chlorinated solvent is trichloroethylene.

16. The method of claim 9 , wherein the chlorinated solvent is an aggregate of chlorinated solvents.

17. A method comprising:
providing a plurality of turbid aqueous chlorinated solvent calibration solutions, the calibrations solutions comprising solutions of water and a chlorinated solvent, each calibration solution having a turbidity value in a predetermined turbidity range, each calibration solution having a concentration of the chlorinated solvent within a predetermined concentration range, at least two of the chlorinated solvent calibration solutions samples having different concentrations within the predetermined range;
measuring intensity of Raman return at a predetermined Raman shift associated with O—H stretching region of water for each of the plurality of turbid aqueous chlorinated solvent calibration solutions;
developing a calibration profile for turbid solutions relating concentrations of the plurality of the turbid aqueous chlorinated solvent samples to the measured intensities;
obtaining a turbid aqueous solution sample whose chlorinated solvent concentration has to be determined, the sample containing the chlorinated solvent;
measuring intensity of Raman return at the predetermined Raman shift associated with O—H stretching region of the turbid aqueous solution sample;
comparing the intensity of Raman return at the predetermined Raman shift associated with O—H stretching region of the turbid aqueous solution sample to the calibration profile for turbid solutions; and
determining concentration of the chlorinated solvent in the turbid aqueous solution sample.

18. The method of claim 17 , wherein the predetermined concentration range includes zero concentration.

19. The method of claim 17 , wherein the turbid aqueous solution sample whose chlorinated solvent concentration has to be determined is taken from a geographic region of interest.

20. The method of claim 19 , wherein the geographic region of interest is a well, a body of water, a subsurface water environment, an aquifer, a waste water stream, or an industrial process stream.

Assignees

• Purdue Research Foundation

Inventors

• Sinfield Joseph Victor
• Monwuba Chukwukelue Kenneth

Classifications

• G01N21/65 Primary

  Raman scattering · CPC title

• G01N33/182

  Specific anions in water · CPC title

• Y10T436/193333

  In aqueous solution · CPC title