Abstract
This effort evaluated the potential of two prototype devices for enhanced electrochemical detection of 2,4,6-trinitrotoluene (TNT) and dinitrotoluene (DNT) following preconcentration using an organosilicate sorbent. The bench-scale prototype provides adsorption of the targets from aqueous solution followed by elution in a mixture of methanol and potassium chloride (KCl). Following elution, the eluant is diluted using an aqueous KCl solution to provide sufficient electrolyte for electrochemical analysis. Concentrations of methanol greater than 50% were detrimental to sensor performance and lifetime. Calibration of the electrochemical sensor was completed and results of electrochemical analysis were compared to those of HPLC analysis over a range of concentrations and in varied matrices. TNT detection was found to be consistent and detection limits were improved from 200 ppb to 3 ppb depending on the sample volume utilized. DNT detection showed higher variability and significantly greater false response rates. On the basis of these results, a second, more advanced, prototype was developed and utilized in limited field trials with the intention of moving the technology toward in situ applications.
Highlights
US Department of Defense (DoD) activities have resulted in contamination of the soil and water at a number of military installations
It was first necessary to evaluate the response of the PalmSens electrochemical sensor system to the targets of interest
While other electrolytes were evaluated early in these studies [13], we found that the performance of the sensors when used with potassium chloride was equal to or better than other electrolytes with respect to sensitivity and sensor lifetime
Summary
Congressional mandate requires compliance of the DoD with applicable environmental laws and regulations necessitating monitoring and remediation of a number of contaminated areas These efforts are costly in both the short and long term making more effective and efficient analytical methods of particular interest to the community. The procedure outlined by the US Environmental Protection Agency for colorimetric detection of TNT and RDX relies on adsorption of target from two liters of sample solution onto membranes bearing poly(styrenedivinylbenzne) octadecyl particles [3,4]. Even given this limitation, in situ monitoring offers several advantages over traditional collect and ship methods. Results from limited field trials utilizing a more advanced prototype system are presented
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