5

The presence of explosives (BB) and components of smokeless powders was established by the correspondence of the relative mobility values of substance spots on the chromatograms of the studied and control solutions, as well as by the reaction to the action of developing reagents:
* A solution of diphenylamine in an alcohol-acetone mixture followed by irradiation with UV light with a wavelength of 366 nm.
* A solution of ethylenediamine in acetone.
* A 5% solution of potassium dichromate in a mixture of sulfuric and acetic acids.

GC-MS Study Details

The GC-MS study was carried out on a "GCQ" spectrometer from "Finnigan MAT" (USA).

• Separation:
  • Helium flow at a speed of 50 cm/s.
  • DB-1 column from "J&W Scientific" (USA) with a diameter of 0.25 mm, a phase layer thickness of 0.25 μm, and a length of 10 m.
  • Injected sample volume: 1 μl.
  • Injector temperature: -200 °C.
  • Injector mode: Splitless.
  • Column temperature: Isothermal 70 °C for 1 min, then programmed heating at a rate of 25 °C/min.
  • Ion source temperature: 150 °C.
  • Interface temperature: 250 °C.

Mass spectra of the separated substances were recorded in the chemical ionization mode with methane reagent gas in the mass range of negative ions 35-300 amu. Identification of explosives was carried out by comparing the retention times and mass spectra of the substances in the studied samples and reference samples.

Findings

As a result of the studies conducted, trace amounts were found:
* RDX (hexogen) - a high explosive - in swabs from the objects listed in paragraphs 1.1, 1.2, 2.1, 3.1, 4.1-4.6, 5.1 (about $10^{-8}$ g - $10^{-7}$ g).
* TNT (trotyl) - a high explosive - in swabs from the objects listed in paragraphs 1.1, 1.2, 2.1, 4.1-4.6, 5.1 (about $10^{-4}$ g - $10^{-7}$ g).

Trace amounts of other high explosives (HMX, PETN, nitroglycerin, tetryl and picric acid) at the level of about $10^{-6}$ g - $10^{-8}$ g were not detected.

TNT and RDX can be used as explosives both in individual form and in the form of mixtures with other explosive and non-explosive components. Among mixed explosives containing TNT and RDX, one of the most widely used components is ammonium nitrate.

Ammonium Nitrate Detection

To detect trace amounts of ammonium nitrate, studies were carried out by the IC (ion chromatography) method on a "Star" liquid chromatograph from "Varian" (USA). The eluent was supplied using an isocratic pump model 9002 from "Varian" (USA).

To separate anions in the studied mixture, the following were used:
* An Elsian-6-Kank column from "Elsiko" (Russia) filled with anion-exchange resin.
* A 2x20 mm guard column filled with grafted C18 phase with a particle size of 40 μm.
* A BTS AG suppression column from "Biotronik" (Germany).

Chromatography of the sample was carried out in isocratic mode with a carbonate buffer containing 0.002 M $\text{Na}_2\text{CO}_3$ and 0.002 M $\text{NaHCO}_3$. Eluent flow rate: 2 ml/min.