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Researchers Develop new method to detect hazardous solvents in water and soil

A Purdue University team, led by Joe Sinfield, an associate professor in Purdue’s Lyles School of Civil Engineering, and involving former Purdue researcher Chike Monwuba, has developed a new method to detect the presence of these hazardous solvents in water and soil. The method offers the potential to enhance monitoring operations and improve the efficiency of remediation efforts.

“Our method is accurate, quick and can detect very low concentrations of the target contaminants,” said Sinfield, who also serves as the director of Purdue’s College of Engineering Innovation and Leadership Studies Program.

The Purdue team had initially focused on using Raman spectroscopy to directly detect chlorinated solvents. In this approach, a laser is used to examine a sample and the scattered light is observed to determine its chemical makeup.


The different fundamental light processes during material interaction

“Traditionally, one would look for specific frequencies of scattered light that are indicative of the presence of the chemical of interest,” Sinfield said. “However, after conducting several broad spectral studies of the target compounds in simulated field samples, our team noticed that the light scattered by the water itself was affected by the presence of the chlorinated solvents—in fact more so than the light scattered by the molecules of the target chemical.”

This observation led to the development of a sensing mechanism that is nearly 10 times more sensitive than conventional approaches involving direct observation of the solvents themselves.

Sinfield said the Purdue method also shows promise for detecting chlorine based compounds in other contexts, as well as chemicals such as fluorine, bromine or iodine in an array of application spaces.

The work aligns with Purdue’s Giant Leaps celebration, celebrating the university’s global advancements in health and sustainability as part of Purdue’s 150th anniversary. These are two of the four themes of the yearlong celebration’s Ideas Festival, designed to showcase Purdue as an intellectual center solving real-world issues.

Researchers worked with the Purdue Office of Technology Commercialization to patent the innovation, and they are looking for partners to continue developing it. 

Validation of handheld X-Ray Fluorescence for In-Situ Measurement of Mercury in Soils

Researchers recently reported the results of an evaluation of a handheld X-ray fluorescence (XRF) device as a field screening tool for soil mercury as part of on-going remedial investigations along the South River in Waynesboro, Virginia.  As reported by the research team, the method achieved a detection limit of 7.4 mg/kg Hg with a 60-s analysis time, which improves upon earlier attempts and is sufficient for detecting mercury at generic risk assessment soil screening levels (23 mg/kg Hg).  The study also demonstrated levels of accuracy and precision for the method that rivaled traditional laboratory methods.  In a split-sample comparison with laboratory Method 7471A, field XRF results agreed with an R2 of 0.93 and a median coefficient of variation of 15%.  Precision estimates from duplicate and triplicate samples were not statistically different between the two methods and were constrained by sample heterogeneity rather than by method capabilities.

The study demonstrated that handheld XRF can be successfully used at contaminated sites to achieve high quality Hg results that are accurate, precise, and at a level of sensitivity commensurate with generic risk assessment screening levels.

Schematic of an X-ray fluorescence (XRF) device