SMOKELESS POWDERS LIBRARY

Jess Seng

What is a GC-MS instrument?

Gas Chromatography• Column separates injected sample mixture • Mass of chemicals determines travel time

through column

Mass Spectroscopy • Molecules are charged & put through

magnetic field; become fragmented• Fragment mass & molecular mass used to

name sample

GC-MS

He

HeHe

He

He

& accelerator

Quadrupole

Vacuum Chamber

QUADRUPOLE: ELECTRIC FIELDS

Small ion

Large ion

Just right sized ion

camph

or

nitrog

lyceri

n 2,4-

Di

nitro

toul

ene

Diet

hyl p

htha

late

Diph

enyl

amin

e

Ethy

l Cen

tralit

e2-

Nitro

diph

enyl

amin

eDi

buty

l ph

thal

ate

Diam

yl p

htha

late

4-Ni

troso

diph

enyl

amin

e

Ethylh

exyl

phtha

late

From solvent

9.2 11 1

2

12.3

12.4

13.4

13.5

14 14.2 16.4

13.7

Methyl Centralite

Ethyl Centralite

Accurate-2495

13.2

13.4

Nitroglycerin

Diphenylamin

e

Ethyl Centralite

Hodgdon-LEVERevolution

11 12.4

13.4

What are smokeless powders?

• Smokeless powders are a form of propellant that replaced the use of black powder.• They leave little

residue; found as gun powder residue in guns or as explosive charge in IEDs.

D:

Classes of powders Single-base: nitrocellulose

Double-base: nitrocellulose + nitroglycerine

Triple-base:nitrocellulose + nitroglycerine + nitroguanidine

PROPELLANT AUTO IGNITION

Nitrocellulose slowly breaks down over time

In bulk, released heat could have negative effects

To stop, calcium carbonate may be added

STABILIZER • In order to prevent decomposition products, stablizers

added. • Inserted in low quantities [0.5 – 2.0%]• Over time, stabilizer will degrade, so frequently tested

Common stabilizer? Diphenylamine

Further forms of classification are morphology and color. . .

BURN RATE & SURFACE AREA• Black powders never had distinguishing shapes.• Smokeless powders DO.

NCFS EXPERIMENT PROTOCOL• Weighed out then cut in half 0.010 g of each sample of smokeless powder.

300ųl methylene chloride + smokeless powder [sat for 3 hours]

Extraction: Insert contains 100ųl of previous vial

Dilution: 10ųL of 1st vial placed in insert & 100ųL methylene chloride

PROTOCOL CONTD. . .

• 2 microliter injections of sample analyzed with Agilent ALS autosampler G2614A splitless injector.

• Via transfer line, moves temp changes

PROTOCOL CONTD. . .• Agilent 7890A GC/5975c EI MSD GC-MS used for analysis

• Restek Rtx-5ms crossbond 5% diphenyl/ 95% dimethyl polysiloxane • Helium carrier gas w/ flow rate of 1.2 mL/min on column & 40 cm/sec velocity

ATR FT-IR

Sample platform

Pressure tower/compression tip

ATR FT-IR PROTOCOL

• 2.5 mg uncut powder kernels placed in 100ųL of acetone; sat for 30 minutes

• Supernatant spotted onto microscope slide and allowed to evaporate, topped with another drop of supernatant and film placed on ATR-FTIR

SABRE 5000

• Handheld trace detector for• Explosives• Chemical agents• Toxic industrial

chemicals• Narcotics

Item loaded: Swab

Swab dabbed with sample

Blank swab loaded?

No alert! Keep searching!

Control with drug/bomb sample loaded?

ALERT! STOP! Positive sample acquired!

Future applications of acquired results.• Better compare smokeless powders and look at stabilizers present in the

sample.

Resources

• A Forensic Application of Mass Spectroscopy, Jehuda Yenon

• Practical Bomb Scene Investigation, James T. Thurman• Forensic Analysis on the Cutting Edge, Robert D. Blackledge• A Qualitative Comparison of Smokeless Powder Measurements, William A.

Mac Creham & Michelle R. Reardon• The Manufacture of Smokeless Powders & their Forensic Analysis: A Brief

Preview, Probert M. Heramb• National Center for Forensic Science Smokeless Powder Database

QUESTIONS?

THANK YOU VERY MUCH!