FEASIBILITY OF GUNSHOT RESIDUE DETECTION VIA ITS ORGANIC CONSTITUENTS, PART I - ANALYSIS OF SMOKELESS POWDERS BY COMBINED GAS CHROMATOGRAPHY-CHEMICAL IONIZATION MASS SPECTROMETRY

• NCJ Number: 49639
• Journal: Journal of Forensic Sciences Volume: 23 Issue: 3 Dated: (JULY 1978) Pages: 433-445
• Author(s): M H MACH; A PALLOS; P F JONES
• Date Published: 1978
• Length: 13 pages
• Corporate Author: American Acad of Forensic Sciences
• Sale Source: Aerospace Corporation
• Publication Format: Article
• Language: English
• Country: United States of America

Annotation

THIS PAPER REPORTS GAS CHROMATOGRAPHIC-MASS SPECTROMETRIC ANALYSIS OF VOLATILE ORGANIC COMPOUNDS IN 33 SMOKELESS POWDER SAMPLES TO DETERMINE AN IDENTIFICATION METHOD THAT IS PRECISE, RAPID, AND INEXPENSIVE.

Abstract

SMOKELESS POWDERS COMMONLY USED IN SMALL ARMS AMMUNITION ARE BLENDS OF NITROCELLULOSE AND SMALL AMOUNTS OF STABILIZERS AND PLASTICIZERS, IN ADDITION TO CERTAIN MODIFYING AGENTS. THIRTY-TWO OF THESE POWDERS WERE OBTAINED FROM COMMERCIAL CARTRIDGES, AND ONE WAS A RELOADING POWDER. SAMPLES WERE ANALYZED BY USING GAS CHROMATOGRAPHY AND MASS SPECTROMETRY TECHNIQUES WITH DIFFERENTIALLY PUMPED CHEMICAL IONIZATION SOURCES. SAMPLES WERE INTRODUCED INTO THE MASS SPECTROMETER BY USING A HEATED SOLID PROBE INLET. FOR GAS CHROMATOGRAPHY ANALYSIS, SAMPLES WERE DISSOLVED IN REAGENT-GRADE ACETONE AND ANALYZED BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY. FIVE MAJOR CONSTITUENTS WERE IDENTIFIED BY SPECTRAL ANALYSIS: NITROGLYCERIN; 2,4-DINITROTOLUENE; DIPHENYLAMINE; DIBUTYL PHTHALATE; AND ETHYL CENTRALITE. SLOW HEATING OF SMOKELESS POWDER PARTICLES IN THE MASS SPECTROSCOPY SOLID PROBE INLET DID NOT RESULT IN THE DETECTION OF ANY OF THE FIVE MAJOR VOLATILE COMPONENTS FROM A NITROCELLULOSE MATRIX. THE RESULTS SHOW THAT THERE IS NO SIMPLE WAY TO PREDICT THE COMPOSITION OF A SMOKELESS POWDER BASED ON CALIBER OR BULLET TYPE. SEVERAL PRECAUTIONARY POINTS ARE MADE IN RELATION TO THE ANALYSIS OF RESIDUAL POWDER: (1) IDENTIFICATION REQUIRES THAT POWDER RESIDUE FOUND AFTER FIRING BE CHEMICALLY IDENTICAL TO THE VIRGIN POWDER AND NOT HAVE LOST ONE OR MORE COMPONENTS BY SELECTIVE VOLATILIZATION; (2) POWDER PARTICLES MAY BE CONTAMINATED WITH RESIDUE FROM A PREVIOUS FIRING OF A GUN WITH A DIFFERENT AMMUNITION PREVENTING IDENTIFICATION; AND (3) IDENTIFICATION PRESUPPOSES KNOWLEDGE OF WHETHER A MANUFACTURER REGULARLY USES ONLY ONE KIND OF POWDER FOR EACH PARTICULAR CALIBER/BULLET COMBINATION. SUPPORTING DATA ARE TABULATED, AND REFERENCES ARE INCLUDED. (DP)