Characterisation of gunshot residue from three ammunition types using suppressed anion exchange chromatography

Recent trends in organic gunshot residue analysis

“…Volatile OGSR compounds can be collected from human nasal tissue [2,4], but more often it is associated with the collection of volatile compounds from spent cartridge cases and firearm barrels. The collection of OGSR compounds from cartridge cases generally involves the collection of the case itself in an airtight container [9,13], or seal bag [46], followed by extraction in a laboratory. The use of solid phase micro extraction (SPME) is generally the method of choice for the collection of volatile OGSR compounds from the barrel of a firearm [47][48][49].…”

“…Solvent extraction has been employed for the extraction of OGSR compounds from smokeless (propellant) powders [8,10,11] and spent cartridges [46], as well as OGSR compounds collected on a swab or (modified) stub [12,53] and from vacuum collected samples [45]. Solvent extraction involves dissolving the sample by submerging the powder or object containing the OGSR sample in a solvent for a period of time.…”

“…Solvent extraction involves dissolving the sample by submerging the powder or object containing the OGSR sample in a solvent for a period of time. Dissolving the sample may be done in an aqueous solution [38,46] or in organic solvents, such as methanol [8,12,14], methylene chloride [10,11,45], acetonitrile [10] or methyl ethyl ketone [54]. This process can be aided and thus accelerated, by stirring or (ultra)sonication [8,14,46].…”

“…Stirring, however, was considered to be ineffective by Zeichner and Eldar, who reported that sonication is imperative to achieving an efficient extraction [38]. This is generally followed by centrifugation, which allows for the collection of the supernatant and filtration [8,14,46]. Alternatively, the sample may be concentrated prior to centrifugation by blowing it to near dryness [38], or complete dryness [10][11][12].…”

“…Solvent extraction procedures are employed in conjunction with a wide array of analytical techniques including gas chromatography-mass spectrometry (GC-MS) [8], ultra-high performance liquid chromatography-tandem MS (UPLC-MS/MS) [11], high performance liquid chromatographyultra violet detection (HPLC-UV) [14], liquid chromatography-quadrupole time-of-flight (LC-QTOF) [12], ion exchange chromatography [46], Raman microscopy [54], capillary electrophoresis (CE) [10] and micellar electrokinetic capillary chromatography (MEKC) [14]. The use of organic solvents, however, is both economically and environmentally disadvantageous [8].…”