Within the last decade, several groups have reported successful application of mass spectrometry to the analysis of the organic constituents of firearms discharge residue<sup>[1]</sup>. The target compounds are stabilizer residues, flash suppressors, and other propellant residues generated by a weapon discharge. However, the elemental components of these residues, which arise from the primer (or the weapon itself) are usually analyzed by scanning electron microscopy coupled with x-ray spectroscopy (SEM-EDX). Thus, to take advantage of both organic and inorganic components in FDR, two separate methods are still required. Here we report progress towards characterization of the inorganic constituents of FDR (lead, barium, antimony, copper, iron, etc.) using host-guest complexation coupled to electrospray ionization triple quadrupole mass spectrometry. Complexation has been demonstrated with these elements using crown ethers (15-crown-4 and 18-crown-6) as well as with EDTA type ligands. In general, complexation of antimony has proven most challenging. For this assay, FDR is collected from the hands of shooters using a non-adhesive wall mount material which is extracted sequentially with methanol and then under relatively mild acidic conditions with heating followed by addition of the complexing solution. Flow injection analysis is used to introduce sample into the ion source. Identification of the element is confirmed via multiple reaction monitoring (MRM) of the generic form M-L à M where the cation is detected in Q3 and confirmed using isotopic patterns. Results of experiments with various complexing agents will be presented along with detection limits and applications to authentic shooter hand samples.

Application of host-guest complexation and tandem mass spectrometry to the characteriation of elemental constituents of firearms discharge residue

254th National Meeting (2017)

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