Chemical Approaches In Detection of Explosives.1

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PowerPoint Presentation:

Chemical Approaches In Detection Of Explosives

PowerPoint Presentation:

Explosives LOW HIGH Pyrotechnics Propellants Subsonic Combustion Supersonic Combustion Primary Initiators Secondary “Main Charge ”

EXPLOSIVES:

EXPLOSIVES INITIATORS – Lead Azide , Pb (N3)2 NON-INITIATING HIGH EXPLOSIVES – TNT, DNT, Ammonium Nitrate LOW EXPLOSIVES – Black Powder, Smokeless Powder PERMISSIBLE EXPLOSIVES – Hydrate Inorganic Salts

Why are Compounds Explosive?:

Why are Compounds Explosive? Exothermic combustion Release large amounts of energy and gas Internal oxidant N-oxides (NO, NO2, NO3) as source of O Nitromethane (NM) Δ cH [kJ/mol] -709.2 Combustion velocity [km/s] 6.49 Methane Δ cH [kJ/mol] -890.8 Combustion velocity [km/s] 1.4-1.64

THE USUAL SUSPECTS:

THE USUAL SUSPECTS NITRO ALIPHATICS NITRAMINES NITRO AROMATICS ACID SALTS NITRATE ESTERS PEROXIDES Nitromethane (NM) 2,4,6-trinitrotoluene (TNT) Ammonium Nitrate Triacetone triperoxide (TATP) Hexamethylene triperoxide diamine (HMTD) Nitroglycerine (NG) Trinitro-triazacylohexane (RDX)

PowerPoint Presentation:

EXPLOSIVE DETECTORS BULK DETECTORS TRACE DETECTORS MASS SENSORS BIOSENSORS CHEMOSENSORS

Difficulties for Detection:

Difficulties for Detection Low vapor pressure • Vapor pressure depression • Mixtures • Binders • Packaging • Thermal vaporization causes degradation. • Lack characteristic absorption bands • Increased usage of non-conventional explosives Explosive Vapor press. [ ppt (v/v)] Chloroform 500,000,000 EGDN 100,000,000 NG 580,000 DNT 56,000 TNT 9,500 PETN 18 RDX 6

CHEMOSENSORS Three different polymorphic crystalline structures, including microbelts and flowerlike supernanostructures, were obtained via a simple solution process by utilizing different solvents from an oligoarene derivative. Explosive chemosensors based on these self-assembled organic crystalline nanostructures were successfully fabricated. The differences in the structures on the microscopic level and in the film morphologies led to dramatic enhancements of the explosive detection speed. With the evolution of structures from the netted 1D microbelts to the flowerlike supernanostructures, the detection speed of the chemosensors for DNT and TNT was improved by more than 700 times. Our discovery demonstrates that the morphology control through self-assembly provides a new platform to utilize organic crystalline microstructures for chemosensors, optoelectronics, biosensors and bioelectronics, and so forth.:

CHEMOSENSORS Three different polymorphic crystalline structures, including microbelts and flowerlike supernanostructures , were obtained via a simple solution process by utilizing different solvents from an oligoarene derivative. Explosive chemosensors based on these self-assembled organic crystalline nanostructures were successfully fabricated. The differences in the structures on the microscopic level and in the film morphologies led to dramatic enhancements of the explosive detection speed. With the evolution of structures from the netted 1D microbelts to the flowerlike supernanostructures , the detection speed of the chemosensors for DNT and TNT was improved by more than 700 times. Our discovery demonstrates that the morphology control through self-assembly provides a new platform to utilize organic crystalline microstructures for chemosensors , optoelectronics, biosensors and bioelectronics, and so forth.

CHEMO SENSORS:

CHEMO SENSORS

COLORIMETRIC DETECTION:

COLORIMETRIC DETECTION

Jackson-Meisenheimer Complex:

Jackson- Meisenheimer Complex 2,4,6 Tri Nitro Toluene(TNT) 2,6 Dinitro Toluene (DNT)

Nitrite Assayed With Griess Test:

Nitrite Assayed With Griess Test

Desorption Electrospray Ionization Mass Spectrometry:

D esorption Electrospray Ionization Mass Spectrometry Desorrption Electrospay Ionization (DESI) mass spectrometry is used for rapid,specific & s ensitive detection of trace amounts of the notorious explosive TATP present on ambient Surfaces by alkali metal complexation in a simple spray technique

Multiple Explosives Detection:

Multiple Explosives Detection Optical FIBRE

Fluorescent Quenching For Detection:

Fluorescent Quenching For Detection • ERed : NB (-1.15V) < DNT (-0.9V) < TNT (-0.7V) Increased Reduction Potential = Increased Quenching

QUENCHING EFFICIENCY:

Relative FluorescenceQuenching QUENCHING EFFICIENCY Quenching efficiency directly related to reduction potential: TNT (-0.7V) > DNT (-0.9V) > NB (-1.15V) CONCENTRATION OF EXPLOSIVES(M) TNT DNT NB

Psi Detects Nitro Aromatics:

Psi Detects Nitro Aromatics Poly( tetraphenylsilol ) [ PSi ] • PROS : excellent sensitivity and selectivity, cheap, easily synthesized, readily fielded for on-site use, and nontoxic • CONS : limited to nitroaromatics , interference from UV absorbers

FIDO:

FIDO LOD in femto -gram range( ppq ). Detection of vapour & particulates.

ACRO-PET:

ACRO-PET • Acid catalyzed decomposition • Horse-radish peroxidase • ABTS color detection • PROS : high selectivity, fast, cheap, disposable • CONS : moderate sensitivity (mg), interference

THANKING YOU:

THANKING YOU “ I dont know with what WORLD WAR III will be fought, but I am pretty sure World WAR 4 will be fought with sticks & stones .” -ALBERT EINSTIEN

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