Field-Deployable Sniffer for 2,4-Dinitrotoluene Detection

Abstract

A field-deployable instrument has been developed to detect low-level 2,4-dinitrotoluene (2,4-DNT) vapors. The system is based on previously developed artificial nose technology and employs an array of sensory materials attached to the distal tips of an optical fiber bundle. Both semiselective and nonspecific, cross-reactive sensors were employed. Each sensor within the array responds differentially to vapor exposure so the array's fluorescence response patterns are unique for each analyte. The instrument is computationally "trained" to discriminate target response patterns from nontarget and background environments. This detection system has been applied to detect 2,4-DNT, an analyte commonly detected on the soil surface above buried 2,4,6-trinitrotoluene (TNT) land mines, in spiked soil and aqueous and ground samples. The system has been characterized and demonstrated the ability to detect 120 ppb 2,4-DNT vapor in blind (unknown) humidified samples during a supervised field test.

Multilayer Optical Filters for Automatic Detection of Analytes in Mixtures with Interferrants - Basic Research in Materials and Techniques

“…21 . ITTFA is a powerful mathematical tool to deconvolute spectra with broad overlapping spectral features.…”

“…The performance of the instrument with explosives vapors is the subject of another manuscript. 21 The performance with different fragrances is the subject of yet another manuscript. 22 In both studies we were able to show that pattern recognition based on the sensor responses could selectively identify and even quantify (within limits) vapor- phase analytes.…”

Automatic decoding of sensor types within randomly ordered, high-density optical sensor arrays

“…Vapor delivery, emission scan, data collection, and image processing Our sparging vapor-delivery apparatus, similar to one developed by Kauer and Shepherd [35], has been well-documented and employed for many detection tasks in our laboratory [1,2,4,9,17,18,19,20,22,36]. All solvent or solid analytes were placed in individual sealed flasks for vapor delivery; for delivery of "air" (the blank) an empty sealed flask was used to purge the carrier (air) gas on to the sensors.…”

“…The concentration and polarity of the vapor can be monitored by Nile Red by means of time-dependent spectral changes (excitation/emission shifts and/or intensity change), which form unique patterns for each odor [1,17,18]. These fluorescence-based microbeads have proven to be effective sensors for detecting lowlevel nitroaromatic compound vapors [1,2,9,19,20] and discriminating simple and complex odors [1,21]. As reported herein, these unique and reproducible sensor odor patterns can be used to identify, or decode, different types of sensor when they are combined and randomly distributed on a high-density array platform.…”

“…As reported herein, these unique and reproducible sensor odor patterns can be used to identify, or decode, different types of sensor when they are combined and randomly distributed on a high-density array platform. This paper does not elaborate on odor discrimination, which has previously been documented for similar types of sensors [1,2,4,9,19,20,21,22].…”