ISSN: 0022-1198
CODEN: JFSCA
Page Count: 8

Detection of Trace Levels of Gasoline in Arson Cases by Gas Chromatography-Mass Spectrometry with an Automatic On-Line Thermal Desorber
Seppälä, I
Forensic Chemist; Forensic Chemist, Quality Assurance Manager; and Director of Laboratory, National Bureau of Investigation, Crime Laboratory,

Himberg, K
Forensic Chemist; Forensic Chemist, Quality Assurance Manager; and Director of Laboratory, National Bureau of Investigation, Crime Laboratory,

Kärkkäinen, M
Forensic Chemist; Forensic Chemist, Quality Assurance Manager; and Director of Laboratory, National Bureau of Investigation, Crime Laboratory,

(Received 22 January 1993; accepted 11 June 1993)

Abstract

A method for the analysis of trace levels of gasoline in arson debris using an automatic thermal desorber (TD) and commercial Tenax adsorbent tubes is described. First, a static headspace screening test is performed by gas chromatography using a flame ionization detector (GC-FID). Suspected gasoline is reanalyzed by gas chromatography-mass spectrometry (GC-MS). Gasoline traces smaller than 10 μL in a 1 liter volume are analyzed by a dynamic heated headspace procedure with thermal desorption and GC-MS after adsorption on 45 mg Tenax tubes. The desorption of adsorbed vapors is carried out by heating the tubes; the analytes are focused in cryogenic units cooled with liquid nitrogen. The cryofocused vapor sample is flash-heated for injection into the capillary column of the GC. The dynamic heated headspace technique (TD-GC-MS) is suitable for analyses of trace amounts of gasoline (0.1–10 µL in 1 liter volume).

Keywords:
criminalistics, forensic science, gasoline, gas chromatograph, thermal desorption, arson, debris, trap, cryo, GC-MS, chemical analysis

Paper ID: JFS13584J
DOI: 10.1520/JFS13584J
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