Transcript Forensic Analysis of Pens and Inks

Forensic Analysis of Pens & Inks
Video link
• http://www.youtube.com/watch?v=I34tz5nIP
Cs 9 min
• Inks appearing on questioned documents may
be examined for the purpose of comparing
with other inks on the same document, with
ink on other documents or even with ink in
seized pens.
• Aging is an important
forensic aspect for ink
analysis. If an old
document has been
altered recently, the newer
ink will have a different
composition to the old,
aged ink and should be
detectable by the
appropriate technique
Inks
• Inks are complex mixtures of colorants,
vehicles, and additives, which are adjusted in
composition to produce the desired writing
characteristics
Analytical Techniques
• Infrared, Mass Spectrometry, Gas
Chromatography, and high-performance liquid
chromatography, have been used to study
different ink components for identification
purposes
Types of Pens
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Ballpoint
Rollerball
Fountain
Felt
Ceramic tip
Gel Tip
Ball Point Pen
• A ballpoint pen is a writing instrument which
dispenses a viscous ink from an internal
reservoir through the rolling action of a metal
ball at its point.
• This "ball point" may vary in diameter, and
may be made of brass, steel, or tungsten
carbide
Roller Ball Pens
• use ball point writing mechanisms with waterbased liquid or gelled ink, as opposed to the oilbased viscous inks found in ballpoint pens.
• These less viscous inks, which tend to saturate
more deeply and more widely into paper than
other types of ink, give roller ball pens their
distinctive writing qualities.
• The writing point is a tiny ball, usually 0.5 or
0.7 mm in diameter, that transfers the ink from
the reservoir onto the paper as the pen moves.
Gel Pens
• A gel pen uses ink in which pigment is
suspended in a water-based gel.
• Because the ink is thick and opaque, it shows
up more clearly on dark or slick surfaces than
the typical inks used in ballpoint or felt tip
pens.
Gel Pens
• The increasing popularity of gel pens has seen
them used to sign many legal documents and
as a direct result, they have also become the
subject of forensic scrutiny in cases of
suspected fraud
• Several well-established methods exist for
analyzing inks from ballpoint and fountain
pens, but not for inks from gel pens
Fountain Pen
• A fountain pen is a nib pen that, unlike its
predecessor the dip pen, contains an internal
reservoir of water-based liquid ink. The pen
draws ink from the reservoir through a feed to
the nib and deposits it on paper via a
combination of gravity and capillary action.
Felt Pen
• A marker pen, marking pen, felt-tip
pen, flow, marker is a pen which has its
own ink-source, and usually a tip made
of a porous, pressed fibers such as felt .
• Until the early 1990s the most common
solvents that were used for the ink were
toluene and xylene.
• Today, the ink is usually made on the
basis of alcohols (e.g. propanol, butanol,
diacetone alcohol and cresols
Ceramic Tip Pens
• wears well and does not broaden when
pressure is applied while writing
Forensics Analysis of Ink
• Chromatography analysis
What is chromatography?
Chromatography (from Greek word for chromos for colour) is the collective
term for a family of laboratory techniques for the separation of mixtures. It
involves passing a mixture which contains the analyte through a stationary phase,
which separates it from other molecules in the mixture and allows it to be isolated.
Which means ...
Chromatography is the physical separation of a mixture into its individual
components.
We can use chromatography to separate the
components of inks and dyes, such as those found in
pens, markers, clothing, and even candy shells.
Chromatography can also be used to separate the
colored pigments in plants or used to determine the
chemical composition of many substances.
http://members.shaw.ca/vict/chemistry_test3.htm
Examples of Chromatography
Liquid Chromatography
Used to identify unknown plant
pigments & other compounds.
Thin-Layer Chromatography
Uses thin plastic or glass trays to identify
the composition of pigments, chemicals,
and other unknown substances.
Gas Chromatography
Used to determine the chemical composition of
unknown substances, such as the different
compounds in gasoline shown by each separate
peak in the graph below.
Paper Chromatography
Can be used to separate the
components of inks, dyes, plant
compounds (chlorophyll), make-up,
and many other substances
Mixtures & Compounds
Mixture – Two or more substances that are mixed together, but not chemically
combined.
Examples of mixtures ...
Air – mixture of gases
Bowl of cereal – mixture of cereal and milk
Soda pop – mixture of soda syrup, water, and CO2 gas
Fog –water suspended in air
Kool-Aid – mixture of water, sugar, and flavor crystals
Compounds – Two or more elements that are chemically combined.
Examples of compounds ...
Salt –Sodium and chlorine combined chemically
Water –Hydrogen and oxygen combined chemically
Carbon Dioxide – Carbon and oxygen combined chemically
Solutions
Solutions are mixtures in which one substance is dissolved in another.
Solutions have two parts: solute and solvent
The solute is the substance that is dissolved.
The solvent is the substance that does the dissolving
Identify the solute and solvent in each solution ...
Solution
Solute
Solvent
Lemonade
Soda pop
Ocean water
Solubility - A measure of how much of a given substance will dissolve in a liquid.
A substance that does not dissolve in water is called insoluble.
A substance that does dissolve in water is called soluble.