Raman Spectroscopic In Situ Monitoring of Highly Turbid Media

Journal Article · Thu Mar 12 00:00:00 UTC 2026 · Analytical Chemistry

DOI: https://doi.org/10.1021/acs.analchem.6c00332 · OSTI ID:3030448

Felmy, Heather M.  ^[1]; Boily, Nikolas T. C.  ^[1]; Schafer Medina, Adan ^[1]; Tse, Poki  ^[1]; Westesen, Amy M.  ^[1]; Bello, Job M. ^[2]; Bryan, Samuel A.  ^[1]; Lines, Amanda M. ^[1]

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1. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
2. Spectra Solutions Inc., Norwood, MA (United States)

The ability to run chemical processing more efficiently and cost effectively is a need that spans critical materials recovery and legacy nuclear waste cleanup. Sensors integrated to provide online monitoring are essential to addressing this need by providing near-real time feedback on process conditions, which can improve efficiency, aid in decision making, and reduce the need for grab sample measurements. Optical spectroscopy is well-suited for providing online chemical composition information and has been widely applied in varied chemical systems. However, applications in turbid matrices continue to represent substantial challenges to sensor performance, where absorption or scattering of excitation light can cause significant signal interference. Here, in this study, close-focus Raman probes are investigated for use in turbid media as a way to overcome the signal loss from the scattering of the Raman excitation source. This, paired with advanced data science techniques, allowed for the development of chemometric models for the accurate quantification of several analytes of interest (NO₃^–, NO₂^–, and PO₄^3–) in highly turbid solutions with solids loadings of up to 20 wt %. This work focuses on offline sample measurement and characterization as an initial step toward the development of online monitoring capabilities. Chemical systems of interest were focused on nuclear waste at the Hanford Site, which represents highly complex matrices that could realize significant processing benefits through the integration of online monitoring.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE Office of Environmental Management (EM)
• Grant/Contract Number: AC05-76RL01830
• OSTI ID: 3030448
• Report Number(s): PNNL-SA-214735
• Journal Information: Analytical Chemistry, Journal Name: Analytical Chemistry Journal Issue: 11 Vol. 98; ISSN 1520-6882; ISSN 0003-2700
• Publisher: American Chemical Society (ACS)Copyright Statement
• Country of Publication: United States
• Language: English