Examination of Firearms Review: 2007 to 2010 - Interpol

sensitivity of the method is important. In diesel fuel characterization the Supersonic
GC-MS achieved the ppb -level (ng/ml). Biodiesel samples were also studied but the
analysis was made without pre-treating the samples. The molecular ions of the
samples were discovered. The method was found adaptable to use in forensic
work. 63 Another type of separation capacity is considered when GC-MS is used in
analysing alkylcyclohexanes. The purpose of the method was to determine whether
the residues found in the fire debris were kerosene, gas oil or plastic based. 64
Another suggested method for the characterization of gasoline samples is multidimensional
GC-fourier transform ion cyclotron resonance MS analysis (GC-FT-ICR-
MS). The author of the study refers to fingerprinting crude oils and refined petroleum
products. Therefore the use of chemical ionization, with protonated reagent ions, can
be used to identify the presence of co-eluting isomers in gasoline samples. When
necessary, the method includes dimensions that can be added to the analysis in
order to achieve greater accuracy. 65
A different kind of detector for forensic work, ion mobility spectrometry (IMS), has
been evaluated and developed. An article and a review written about the method, its
history, ion source development and applications serve to deepen the know-how of a
fire analyst. The method is expected to play a significant role in ignitable liquid and
66, 67
arson investigations.
In addition to the study mentioned in the previous section, there have been two novel
studies made; firstly, an application of gas chromatography differential mobility
spectrometry (GC-DMS) with two-way classification of ignitable liquids in fire debris.
The GC-DMS provides unique profiles for different ignitable liquids and, combined
with the fuzzy rule building expert system (FuRES) on two-way data objects, the
system was successful in forensic analysis of fire debris. Also the method seemed
promising for onsite detection for arson investigation. 68 Secondly, the same writer
has published a comparison of different detection methods in order to value their
performances in ignitable liquid classification by using gas chromatography coupled
with either differential mobility spectrometry or mass spectrometry, GC-DMS and GC-
MS respectively. The comparison of the methods was made with projected difference
resolution (PDR) and the results were furthermore verified by FuRES. One-way
datasets were determined in order to calculate minimum resolution values. The
results were that MS data achieved higher resolution, but DMS gained more
informative data. The two way (2D-GC) datasets in neat samples demonstrated that
GC-MS would have had smaller prediction errors than DMS in classifying the
ignitable liquids. No statistic difference occurred between the two methods
considering the high resolution values of neat and spiked samples, yet with burned
samples a smaller prediction error was obtained with GC-MS. 69
Detection of gasoline and paint thinner directly from common household material has
been studied. The analysis method is a direct analysis of real time mass
spectrometry (DART). The method does not need sample pre-treatment. Samples
are introduced at atmospheric pressure and placed into a stream of exited gas, from
which analytes are desorbed and ionized. The method has been demonstrated to be
sensitive and chemical fingerprinting was obtained when samples were analysed
within 1-24 hours after being spiked. Further studies considering matrices and related
effects for detection are proposed. 70 DART is also mentioned in a review article
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