Method for the extraction and electrochemical detection of explosives and explosive components in soils using electrodes, filter paper, and electrolyte
Inventors
Zabetakis, Daniel • Trammell, Scott A. • Dressick, Walter J. • Stenger, David A. • Verbarg, Jasenka
Assignees
Publication Number
US-9557296-B2
Publication Date
2017-01-31
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 voltammetry and/or spectroscopy, thus detecting a possible variation indicative of one or more analytes, wherein the solvent is selected from the group consisting of polar aprotic or protic solvents having a boiling point of at least 100° C., room temperature ionic liquids, and deep eutectic solvents.
Core Innovation
The invention relates to a method for detecting explosives and explosive components in soils or on surfaces using filter paper wetted with a solvent, followed by electrochemical detection through voltammetry and/or spectroscopy. The method includes contacting the soil or surface with the prepared filter paper and analyzing it to detect variations indicative of analytes, with the solvent selected from deep eutectic solvents, room temperature ionic liquids, or polar aprotic or protic solvents having a boiling point of at least 100° C. This approach employs inexpensive, disposable chemical sensor probes that can be mounted on unmanned aerial vehicles (UAVs), enabling site analysis without the need for ground-based human intervention.
The problem solved is the need for a simple, rapid, reliable, and inexpensive method for detecting explosives in the field, particularly one that does not require manual sampling or contact with suspect sites. Existing methods suffer from limitations such as bulk sample requirements, slow laboratory analysis, logistical complexity, low sensitivity to explosives in soils, or the need for direct human operation on-site. Remote sensing technologies available have insufficient sensitivity or cannot distinguish explosives signatures from background in soils. Therefore, a method that integrates sample collection, extraction, and electrochemical detection remotely, with minimal logistic demands and high specificity, is required.
The invention combines solvating filter paper with suitable high boiling solvents and electrolytes, allowing for extraction of explosives and analytes directly from soils via capillary action and electrochemical detection on metal or carbon electrodes, which can be modified for enhanced selectivity. The solvent mixtures, such as ethylene glycol and choline chloride (a deep eutectic solvent), serve both as a solvent to extract explosives and as an electrolyte for voltammetric detection, while the filter paper manifests as a lightweight, disposable sampling medium. The method can be integrated with UAV platforms to enable remote, in situ or ex situ analysis of suspect areas, supporting military operations and other chemical detection tasks.
Claims Coverage
The patent includes one independent claim defining a method of detection using a filter paper and a specified solvent, and dependent claims elaborating on analytes, analytical methods, and UAV implementation.
Use of a filter paper wetted with ethylene glycol and choline chloride deep eutectic solvent for analyte extraction and detection
The method involves contacting soil or a surface with filter paper wetted with a deep eutectic solvent composed of ethylene glycol and choline chloride, enabling extraction of analytes for subsequent electrochemical detection by voltammetry.
Electrochemical detection by voltammetry of analytes extracted on filter paper
Detection is performed by subjecting the filter paper to voltammetry, specifically cyclic voltammetry, to detect a variation in current indicative of analytes such as explosives.
Ability to detect explosives and other analytes
The method detects one or more analytes that include explosives, drugs, nerve agents, biothreats, pesticides, or industrial pollutants.
Analyte migration on filter paper prior to detection
The method may include allowing migration of at least one analyte across the filter paper prior to voltammetry to facilitate removal of interferents and enhance detection.
Use of modified electrodes
Voltammetric detection is conducted using copper-modified screen printed electrodes and/or carbon electrodes.
Sampling performed by unmanned aerial vehicle
The contacting of soil or surface with the filter paper wetted with solvent is performed by an unmanned aerial vehicle, enabling remote sample collection.
These inventive features define a novel method for remote electrochemical detection of explosives and other analytes using solvent-wetted filter paper and voltammetry, implemented on UAV platforms, with specific solvents and electrode modifications to enhance sensitivity and selectivity.
Stated Advantages
Ethylene glycol/choline chloride solvent is slow to evaporate, enabling analysis without needing sealed chambers.
Filter papers saturated with solvent allow direct soil sampling by UAVs while preventing electrode fouling by soils, which is counterintuitive and non-obvious.
Electrochemical detection in air-saturated solvent eliminates the need to purge oxygen, simplifying field operations.
The wicking property of filter paper facilitates removal of electrochemically active interferences such as natural organic matter, enhancing trace detection sensitivity.
Electrode modification enables selective detection of specific analytes like nitrates and chlorates.
Documented Applications
Remote detection of explosives and explosive components in soils using UAV-mounted sensor probes.
Detection of other chemicals including illicit drugs, nerve agents, biothreats, pesticides, industrial pollutants, and toxic industrial compounds.
Electrochemical detection of nitrates and trinitrotoluene (TNT) in different soil types.
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