A method to control the polymorphic phase for RDX-based trace standards

Brady, John J.; Argirakis, Brittney L.; Gordon, Alexander D.; Lareau, Richard T.; Smith, Barry T.

doi:10.1117/12.2223837

Cited by 4 publications

(4 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The research described here aims to expand upon and build on previous work by exploring various solvents, deposition methods, as well as mass loadings and their effect on the polymorphic phase of RDX. 23 The sample preparation techniques that were explored in this work were drop cast crystallization, aerosol spray deposition (ASD), and dry transfer. 24 Herein, we demonstrate that the dry transfer methodology is capable of converting b-RDX to a-RDX regardless of the material (i.e., RDX versus C-4), the initial solvent used to dissolve the sample, initial deposition technique, or mass loading.…”

Section: Introductionmentioning

confidence: 99%

Polymorphic Phase Control of RDX-Based Explosives

Brady¹,

Argirakis

Gordon

et al. 2017

Appl Spectrosc

Self Cite

View full text Add to dashboard Cite

The polymorphic phase of 1,3,5-trinitro-1,3,5-triazine (RDX) was examined as a function of mass loading, solvent, and sample deposition technique. When RDX was deposited at a high mass loading, the vibrational modes in the obtained Raman spectra were indicative of concomitant polymorphism as both the α-RDX and β-RDX phases were present. At low mass loadings, only β-RDX was observed regardless of solvent when using the drop cast crystallization method. However, α-RDX (the thermodynamically stable polymorphic phase observed with visible quantities of the explosive) was observed when RDX deposits were dry transferred. Observation of α-RDX was independent of the initial mass loading or the initial deposition solvent when using the dry transfer methodology. These data indicate that the use of the dry transfer preparation method can be used to successfully prepare RDX-based test articles with the α-RDX phase regardless of the solvent used to initially dissolve the RDX, the initial deposition technique, or the mass loading.

show abstract

Section: Introductionmentioning

confidence: 99%

Polymorphic Phase Control of RDX-Based Explosives

Brady¹,

Argirakis

Gordon

et al. 2017

Appl Spectrosc

Self Cite

View full text Add to dashboard Cite

show abstract

“…This protocol uses RDX particle standards produced by inkjet printing that have a known particle size distribution and a known area distribution when transferred onto the test surface. Other dry-transfer samples 13 can be used if the same parameters are known. Samples produced by direct solution deposition onto the test surfaces are not recommended.…”

Section: Protocolmentioning

confidence: 99%

“…The desired particle diameters, as determined by analysis of fingerprints containing trace explosives, is 10 to 20 μm. Deposits can also be formed by pipetting microliter volumes of solution onto Teflon substrates 13 , but they will dry into a single large deposit, generally much larger that the desired range of particle sizes (for RDX masses relevant to this work). The inkjet RDX particle standard is used in this work along with quantitative extraction and analysis procedures to demonstrate the method for determining wipe collection efficiency.…”

Section: Introductionmentioning

confidence: 99%

Standardized Method for Measuring Collection Efficiency from Wipe-sampling of Trace Explosives

Verkouteren

Lawrence

Staymates

et al. 2017

JoVE

View full text Add to dashboard Cite

One of the limiting steps to detecting traces of explosives at screening venues is effective collection of the sample. Wipe-sampling is the most common procedure for collecting traces of explosives, and standardized measurements of collection efficiency are needed to evaluate and optimize sampling protocols. The approach described here is designed to provide this measurement infrastructure, and controls most of the factors known to be relevant to wipe-sampling. Three critical factors (the applied force, travel distance, and travel speed) are controlled using an automated device. Test surfaces are chosen based on similarity to the screening environment, and the wipes can be made from any material considered for use in wipe-sampling. Particle samples of the explosive 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) are applied in a fixed location on the surface using a dry-transfer technique. The particle samples, recently developed to simulate residues made after handling explosives, are produced by inkjet printing of RDX solutions onto polytetrafluoroethylene (PTFE) substrates. Collection efficiency is measured by extracting collected explosive from the wipe, and then related to critical sampling factors and the selection of wipe material and test surface. These measurements are meant to guide the development of sampling protocols at screening venues, where speed and throughput are primary considerations.

show abstract

“…This approach relies on the drying process to produce appropriate analyte particles with characteristics (such as size and shape) that simulate residues collected from fingerprint deposition after handling bulk explosives. 36–41 Trace explosive particles transferred through fingerprint deposition, such as RDX and pentaerythritol tetranitrate (PETN) from handling C-4 and Semtex H, ranged from less than 1 μm to greater than 50 μm in diameter. 42 Early studies 36,43,44 have used fluorescent polystyrene latex (PSL) microspheres within that particle size range.…”

Section: Introductionmentioning

confidence: 99%

A new wipe-sampling instrument for measuring the collection efficiency of trace explosives residues

et al. 2018

View full text Add to dashboard Cite

Trace explosives detection, a crucial component of many security screening environments, commonly employs wipe-sampling. Since collection of an explosive residue is necessary for detection, it is important to have a thorough understanding of the parameters that affect the efficiency of collection. Current wipe-sampling evaluation techniques for explosive particles have their limits: manual sampling (with fingers or a wand) is limited in its ability to isolate a single parameter and the TL-slip/peel tester is limited to a linear sample path. A new wipe-sampling instrument, utilizing a commercial off-the-shelf (COTS) 3D printer repurposed for its XYZ stage, was developed to address these limitations. This system allowed, for the first time, automated two-dimensional wipe-sampling patterns to be studied while keeping the force and speed of collection constant for the length of the sampling path. This new instrument is not only capable of investigating the same parameters as current technology (wipe materials, test surfaces, forces of collection, and linear sample patterns), it has added capabilities to investigate additional parameters such as directional wipe patterns (i.e. "L" and "U" shapes, square, and serpentine) and allowing for multiple lines to be sampled during a single collection without the need for adjustments by the user. In this work, parametric studies were completed using 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) and the COTS 3D printer for wipe-sampling to establish collection efficiencies for numerous scenarios. Trace explosives detection in field screening environments could be greatly improved with the ability to comprehensively investigate how a wide range of parameters individually affect collection by wipe-sampling. A screener who knows how to properly interrogate any given surface will be much more efficient at detecting trace explosives.

show abstract

A method to control the polymorphic phase for RDX-based trace standards

Cited by 4 publications

References 15 publications

Polymorphic Phase Control of RDX-Based Explosives

Polymorphic Phase Control of RDX-Based Explosives

Standardized Method for Measuring Collection Efficiency from Wipe-sampling of Trace Explosives

A new wipe-sampling instrument for measuring the collection efficiency of trace explosives residues

Contact Info

Product

Resources

About