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Forensic Science International 206 (2011) 150–154
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Contents lists available at ScienceDirect
Forensic Science
s1. Introduction
Arson is one of the easiest crimes to commit. Even the use of a
small amount of an ignitable liquid can cause considerable
monetary damage as well as endanger human lives.
Ignitable liquids are used in a wide variety of activities in our
daily lives. Gasoline is particularly common as a source of energy in
vehicles. In Israel gasoline accounts for some 80% of the found
flammable liquids in arson cases which are detected.
The process of arson is not at all complicated. A flammable
liquid is poured on an item, and then ignited with amatch. There is
no need for professional knowledge, prior experience, or a license
to possess a controlled substance. In the United States, for example,
an estimated 30,500 cases of intentionally set fires in structures
were reported by the U.S Fire Administration in 2008 alone. These
fires took the lives of 350 persons [1].
The combustion process and associated heat release combine to
create damage that reduces traces such as fingerprints and DNA
[2], thus there is limited possibility to tie the perpetrator to the
scene.
One forensic method to connect the perpetrator to the crime is
to find evidence on his body. Contact with ignitable liquid when
transporting it to the scene of crime, and particularlywhen pouring
it, is apt to leave traces on clothes, shoes, or hands.
Previous studies have been conducted concerning the transfer
and presence of ignitable liquids on clothes and shoes [3–5], but
very few studies have been published dealing with the detection of
accelerants on the skin, and especially on the hands of a suspect.
There has been research concerning the penetration and
adsorption of petroleum products into the skin. The basic working
assumption is that hydrocarbons tend to remain in the outer skin
layers, particularly in the stratum corneum [6,7].
Usual swabbing methods do not yield satisfactory results to
extract ignitable liquids from hands, perhaps because hydrocarbon
residues are trapped in the epidermis, and swab methods are not
adequate to extract them [8,9].
A field test to readily sample and extract organic ignitable
liquids on the palm of a suspect is required.
Almiral et al. propose an extracting method using solid phase
microextraction (SPME) and further gas chromatograph (GC)
analysis for traces of ignitable liquids on skin [10]. The method is
sensitive, anda small amountofaccelerant canbedetected. Tracesof
ignitable liquids have been observed on hands more than 3 h after
the application of 10mL of the substances. Themethod, however, is
not very practical: the SPME fiber is not a field kit, and the suspect
must be brought to a laboratory immediately after his arrest.
Darrer et al. suggest dressing the suspect’s handswith polyvinyl,
polyethyleneor latex gloves for 20 min, then adsorbing the ignitable
liquid residue on the gloves using an activated carbon strip (ACS) for
16 h at 60 8C. The ACS is then analyzed using gas chromatograph–
massspectrometer (GC–MS) [8]. In thearticleofDarreretal. tracesof
gasoline are detected on gloves after several hours, when 500–
1000mL of gasoline had been poured on the hand.
Montani et al. recently evaluated the amounts of different glove
backgrounds; they suggest covering the suspect’s hands with latex
gloves. They even developed a prototype kit containing latex
* Corresponding author. Tel.: +972 25429435; fax: +972 25428599.
E-mail address: dlikim@police.gov.il (D. Muller).
0379-0738/$ – see front matter  2010 Elsevier Ireland Ltd. All rights reserved.
doi:10.1016/j.forsciint.2010.07.031Detection of gasoline on arson suspects’
Dan Muller *, Aharon Levy, Ran Shelef
Division of Identification and Forensic Science, Israel Police, National Headquarters, Jeru
A R T I C L E I N F O
Article history:
Received 8 February 2010
Received in revised form 30 June 2010
Accepted 22 July 2010
Available online 21 August 2010
Keywords:
Arson
Gasoline
Activated charcoal
Hands
Forensic sciences
GC–MS
A B S T R A C T
An arson suspect’s contact w
his hands, but detecting the
gasoline detection even 3 h
charcoal strips to adsorb the
hands to 45 8C significantly
This methodology is par
station. Samples are taken
The suggested method
liquids on suspect’s hands.
journal homepage: www.e lands
em 91906, Israel
th an ignitable liquid container can leave small traces of the substance on
traces is difficult. This research paper presents a method to obtain clear
fter hands have been moistened with 50 mL of gasoline using activated
nitable liquid traces directly from the suspect’s hands. Light heating of the
creases the ability to detect gasoline traces.
f a system to sample a suspect’s hands at the scene of crime or in a police
investigators then analyzed in a laboratory.
ovides an important improvement in detection sensitivity for ignitable
 2010 Elsevier Ireland Ltd. All rights reserved.
International
evier .com/ locate / forsc i in t

gloves for the sampling of ignitable liquids [9]. Theymention that a
decrease in the amount of gasoline is to be expected, but the
timeframe is not clear. They do not relate to this decrease in an
experimental mode.
This article proposes a new field test that is both practical and
sensitive for extracting and sampling gasoline residues on the skin.
A charcoal strip is placed on the suspect’s palms, and the hand is
inserted into a sealed bag at room temperature or with a gentle
warming of the hand. The gasoline is extracted from the strip by
dichloromethane (DCM) then examined by GC–MS.
Adsorption of vapors from ignitable liquid residues on charcoal
strips is one of the most commonly used method for sampling fire
debris prior to analysis, but there is no research into adsorption of
ignitable liquids from hands by charcoal strips, probably because
the technique usually requires heating of the exhibit for several
hours [11–13].
In the research presented here the presence of a very little
amount of gasoline was detected on the palm by adsorption with
charcoal strips. Gasolinewas used, because it is themost commonly
encounteredaccelerant in Israel andprobably throughout theworld.
2. Materials and methods
2.1. Materials
 Lead-free gasoline of 95 octane was obtained from Paz Oils and Chemicals (Haifa,
Israel).
Standard samplingwasconducted forcomparison:1mLofgasolinewasdrippedon
tissue paper and inserted into a nylon bagwithhalf of an absorbent strip. The bagwas
heated for 15 h at 60 8C. Extraction from the strip was then performed using DCM.
Passive adsorption on charcoal strips at room temperature: 50mL of gasoline
was dripped onto the palms of each of the three volunteers using a glass syringe.
After 60 or 180 min half of a strip (8 mm  10 mm)was placed on the palm, and the
palm was sealed in a polyamide bag for 15, 60, 120 or 180 min.
Only half of the strip was used in all of the experiments, because the second half
is used in the proposed method for blank processes.
Passive adsorption on charcoal strips with light heating: 50 mL of gasoline was
dripped by a glass syringe onto the palms of each of the three volunteers. After 60 or
180 min half of a strip (8 mm  10 mm)was placed on the palm. The handwas then
sealed in a polyamide bag heated at 45–48 8C by placement under a heating light
(Phillips, 250 W) at a distance of 26 cm from the lamp for 15, 30 or 60 min.
2.3. Extraction from the strips and sampling to GC–MS
After the gasoline was adsorbed from the hand, the half strip was inserted into a
conical vial, and 100 mL of DCM was added for extraction of the gasoline.
The vials were vigorously agitated for 1 min, and then 5 mL of the solvent was
inserted into the injector of the GC–MS.
The analysis instrument was a Thermo Trace Ultra GC coupled with a Thermo
DSQ quadrupole detector. The GC column was an Altech-fused silica capillary
column 30 mm  0.25 mm (i.d.) coated with AT-1 (0.25 mm film). The column
temperaturewas kept at 40 8C for 2 min, and then heated to 130 8C at a rate of 10 8C/
min. The transfer line was kept at 250 8C, and the source temperature at 200 8C; the
scan range was 30–300 Da; filament delay was 2 min. Carrier gas was helium; the
flow was 3.2 mL/min. During the entire duration of the study maintenance tunes
were performed daily to check the repeatability of the instrument. The injections
were carried out in weak split mode, split ratio 3:1.
Integration was automatically done at ions 91, 105 and 119 by a qualitative
ginn
ank—
D. Muller et al. / Forensic Science International 206 (2011) 150–154 151 Dichloromethane (DCM) and N,N-dimethyl-formamide (DMF) AR were pur-
chased from Bio Lab Ltd. (Jerusalem, Israel).
 M & Q polyamide roasting bags were purchased from Hanamal Packaging and
Marketing Ltd. (Beer Yaakov, Israel).
 Nylon arson evidence bags were purchased from Grand River Products, LLC
(Grosse Pointe Farms, MI).
 Activated charcoal strip devices (8 mm  20 mm) were purchased from Albrayco
Technologies, Inc. (Cromwell, CT).
2.2. Sampling procedures
Three volunteers participated to the experiment. Care was taken to prevent
contamination:
 The strips were stored in closed nylon bags not kept in the laboratory.
 Hands were sampled before dripping the gasoline.
 The volunteers had no contact with ignitable liquids during the experiments.
[(Fig._1)TD$FIG]
Fig. 1. TIC chromatograms (a) after adsorption during 60 minwithout heating. The be
(c) Blank—60 min adsorption of hand without previous dripping of gasoline. (d) Blidentification processing setup of XCalibur (the Thermo instrument processing).
3. Results and discussion
Fig. 1 shows the total ion chromatography (TIC) adsorption at
room temperature during 60 min. The beginning of the adsorption
was 60 min after dripping 50mL of gasoline on the hand. Toluene,
C2-, C3- and C4-alkylbenzene are clearly seen. This chromatograph
meets the ASTM requirements for the identification of gasoline [14].
The authors first examined the influence of adsorption time on
the results. Adsorptions were performed at room temperature for
different lengths of time. The strip was placed on the palm for 15,
60, 120 or 180 min, 1 h after dripping 50 mL of gasoline.
After adsorption of 15 min the TIC chromatogram of gasoline
was insuficient to conclude the presence of gasoline, however on
ing of the adsorptionwas 1 h after dripping 50 mL of gasoline. (b) Standard gasoline.
sampling by placing an ACS in an empty bag for 60 min.