Spectroscopic method for the extraction and electrochemical detection of explosives and explosive components in soils using filter paper, and electrolyte
Inventors
Zabetakis, Daniel • Trammell, Scott A. • Dressick, Walter J. • Stenger, David A. • Verbarg, Jasenka
Assignees
Publication Number
US-9857294-B2
Publication Date
2018-01-02
Expiration Date
2034-08-27
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Abstract
Described herein is an approach using inexpensive, disposable chemical sensor probes that can be mounted on a small unmanned aerial vehicles (UAVs) and used to analyze a site (such as one known or suspected to contain explosive residue, spilled material or contaminated soil) without the need for a person to conduct ground operations at the site. The method involves contacting a soil or a surface with a filter paper wetted with a solvent, then subjecting the filter paper to spectroscopy, thus detecting a possible variation indicative of one or more analytes, wherein the solvent is a deep eutectic solvents consisting of a mixture of ethylene glycol and choline chloride.
Core Innovation
The invention described is a method for detecting explosives and explosive components in soils using filter paper wetted with a solvent, specifically a deep eutectic solvent consisting of a mixture of ethylene glycol and choline chloride. The method involves contacting a soil or surface with the wetted filter paper and then subjecting the filter paper to spectroscopy to detect optical property changes indicative of one or more analytes. This approach allows for extraction and electrochemical detection of explosives from soils, employing inexpensive, disposable chemical sensor probes that can be mounted on small unmanned aerial vehicles (UAVs) for remote analysis without the need for personnel to conduct ground operations at the site.
The problem addressed is the difficulty and limitations in current explosives detection methods, especially in military and counterinsurgency contexts. Existing technologies such as liquid chromatography, mass spectrometry, hand-held IR and Raman spectroscopy, electronic nose technologies, and laser standoff detection suffer from constraints including slow operation, need for bulk samples, manual sample collection, limited sensitivity in soils, and risk to personnel conducting ground-level analysis. There is a strong demand for a simple, rapid, reliable, and inexpensive field method that can detect explosives and related analytes remotely and effectively without logistical complexity.
The invention solves this problem by integrating sample collection, processing, and analysis in a compact and mobile system that uses filter paper impregnated with the ethylene glycol/choline chloride solvent mixture. This solvent serves both to extract explosive compounds such as nitro-aromatics and nitrates from soil and as an electrolyte suitable for electrochemical detection via modified electrodes. The method can be performed onsite or remotely by UAVs, and includes steps of wicking analytes across the paper to remove interferents, enhancing detection accuracy. Electrochemical techniques including cyclic voltammetry detect signature changes, while the filter paper also supports spectroscopic methods like Fourier transform infrared spectroscopy and Raman spectroscopy.
Claims Coverage
The patent presents one independent claim detailing a method of detection employing specific steps and solvent composition.
Use of filter paper wetted with a deep eutectic solvent for analyte extraction and detection
The method includes contacting a soil or surface with filter paper wetted specifically with a deep eutectic solvent consisting of a mixture of ethylene glycol and choline chloride, enabling extraction of analytes from the sample.
Spectroscopy for detection of analytes indicated by optical property changes
After contacting the sample, the filter paper is subjected to spectroscopy to detect any change in optical properties indicative of the presence of one or more analytes.
The independent claim covers a method combining the use of filter paper wetted with a specified deep eutectic solvent and spectroscopic detection of analytes through optical property changes, enabling extraction and detection of explosives and other analytes in soil.
Stated Advantages
The ethylene glycol/choline chloride solvent is very slow to evaporate, allowing adequate time for analysis without a sealed system.
The solvent acts as both an electrolyte with a large electrochemical potential window and as a solvent to extract explosive components, enhancing detection sensitivity.
Electrodes do not foul in the presence of soil when used with the filter paper and solvent, contrary to expectations, maintaining detection capability.
Detection of explosives such as TNT or nitrates is feasible in air-saturated solvents, eliminating the need for inert atmosphere purging, simplifying field work.
The filter paper's wicking property removes electrochemically active interferents like natural organic matter, improving trace-level detection.
The method is compatible with remote operation via UAVs, enabling rapid and safe analysis of suspect sites without ground personnel exposure.
Documented Applications
Detection of explosives and explosive components in soil samples at sites suspected of contamination.
Use with small unmanned aerial vehicles (UAVs) for remote sampling and analysis without requiring personnel on the ground.
Electrochemical detection of military-grade and homemade explosives, including nitro-aromatic compounds and nitrates.
Detection of other analytes such as drugs, nerve agents, biothreats, pesticides, and industrial pollutants.
Electrochemical and spectroscopic analysis of soil and surface contamination for military and environmental monitoring applications.
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