Turbidity Correction for Aqueous Raman Spectroscopic Measurements

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2014-SINF-66635
Turbidity is the measure of the loss of optical transparency of a medium resulting from the presence of suspended solids or other interfering matter. This is especially common in aqueous media in natural environments. While the suspended solids can be removed, for example via filtration, that removal can have significant influence on the accuracy of spectroscopic readings and tests. Improvements in diode laser, fiber optic, and data acquisition technologies allow for increased use of Raman spectroscopic techniques for both in lab and in situ water analysis, but there remains a need for methods to correct for turbidity.

Researchers at Purdue University have developed a new technique to correct turbidity effects in two different scenarios, i.e., when the analyte has a weak influence on the Raman spectrum of water and when it has a strong influence. Changes in the Raman return associated with the OH stretching band of water are employed as a correction for strong scatterers, such as ammonium nitrate, which have little influence on water's Raman return. A direct measurement of turbidity is used as a correction for weak scatterers, such as trichloroethylene, which have notable impact on the Raman response of water. These corrective procedures enables quantitative Raman spectroscopic measurements of analyte presence in highly turbid waters. Similar procedures may apply to other liquid systems.

Advantages:
-Allows for the quantitative Raman analysis with turbid aqueous solutions
-Enables in situ analysis

Potential Applications:
-Waterway analysis
-Laboratory analysis
-In situ anaylsis
Jan 15, 2015
Utility Patent
United States
9,863,881
Jan 9, 2018

Jan 15, 2014
Provisional-Patent
United States
(None)
(None)
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