Abstract:
Metal cans are one of the regularly utilized containers for fire debris sampling. When
lined cans are used, co-extraction of interfering compounds from the can’s lining may
cause false data interpretation. Accordingly, unlined metal cans are recommended to
avoid this potential problem. Since unlined metal cans are not vapor tight, heavy loaded
volatile matter can escape easily and even trace quantities can leak during the extraction
procedure. Therefore, this research was carried out (a) to examine the potential crosscontamination
and (b) to interpret data correctly when such cross contaminations occur
through unlined metal cans. Volatile compounds were solvent extracted using heated
passive headspace adsorption by charcoal strips followed by acetone. Analyses were done
using gas chromatography/mass spectrometry (GC/MS) and the data were interpreted
was carried out by visual comparison of the total ion chromatograms or extracted ion
profiling (EIP), considering target compounds concerning the reference chromatogram.
Petrol-free cans, which were kept closely with cans containing known volumes of spiked
petrol from 1 µL – 50 µL, eluted all the target compounds. But the eluting patterns of
chromatograms were different from reference petrol. Typically, 1,2,4-trimethylbenzene is
the prominent peak of the reference petrol chromatogram. In cross contaminations, the
co-eluting peak of 1-ethyl-3-methylbenzene/1-ethyl-4-methylbenzene appeared tallest,
which is second prominent peak in the reference located in the castle group, at low
quantities of spiked petrol samples. Considering high quantities of spiked petrol samples,
both co-eluting peak and 1,2,4-trimethylbenzene appeared with almost the same peak
heights or prominent peak height for the 1,2,4-Trimethylbenzene. Therefore, misinterpreting
of false-positive results can be avoided by examining these pattern distortions.
Further, comparison samples should be examined for background interference prior to
concluding as cross-contamination since they can distort peak patterns
