Sodium flame:
Yellow flame, very distinct. Even a small amount of sodium will contaminate other
compounds
Sodium Hydroxide = Sodium hydroxide is used simply to categorize your samples into two fields: NaOH
reactive- and non-reactive. For this reason, it is extremely useful when using a flowchart. To perform this test, a
few drops of NaOH is added to a small sample of chemical dissolved in water. If a milky-white precipitate forms,
the sample is NaOH reactive. If a precipitate does not form, the sample is NaOH non-reactive. 100, in 55
solutions dissolves nitrile, wool, animal hair, and silk. Acetates, tricitrates, wilk silk, reconstituted protein fibers
dissolve partially/slowly
Polypropylene (PP) = • Blue, yellow tipped flame • Burns slowly • Plastic drips • Has sweet odor • Floats in water • A
common use of PP is in food containers. PP is naturally BPA free and has a high melting point making it dishwasher and
microwave safe. • Due to its resistance to fatigue, most hinge type products are also made from PP (such as flip-top bottles,
lock & lock Tupperware, etc). • PP is often used for storage containers such as Rubbermaid and Sterilite containers. The
softer, rubbery lids are made of a softer plastic, usually LDPE. • Products made from PVC and HDPE can also be made with
polypropylene. For instance, the infamous PVC piping can also be manufactured using PP. HDPE furniture such as tables and
chairs can also be substituted using PP. • PP is commonly used in non-woven fabrics (used in diapers and or sanitary
products). • Polypropylene is commonly used for producing ropes, carpets and recycled plastic rugs. • Many stationary
products such as plastic folders, notebook covers, paper protectors, storage boxes are also made from PP. These products are
made through the plastic extrusion process.
Sulfuric Acid - dissolves acetates, tricitrates, rayons, silk, nylon. NOT cotton, linen, cellulosic plant fibers. If 70% sulfuric
acid then dissolves all
Acetic Acid - at 20, 100% acetic dissolves acetates, at 100 can dissolve acetates/triacetates, nylon very slow
Cotton = - Vegetable - Most widely used plant fiber, fairly short fibers - burns with a
steady flame, smells like burning paper, able to blow flame from thread like a match,
leaves a charred whitish ash - irregular twisted ribbon. Cotton dissolves in bleach(acid-
base reaction)
Linen = -Vegetable - fibers generally longer and smoother than cotton - burns at a
constant rate, does not produce smoke, smells like burning grass, produces sparks -
smooth, bamboo like structur
Wool = - Animal - Most commonly used animal fiber - shrivels, leaves brown-black
residue, smells like burning hair - cylinder with scales. Imbricate hair pattern
Silk = - Animal - Smoother than wool - shrivels, leaves black residue, smells like
burning hair - thin, long and smooth cylinder. Has fibroin(insoluble protein) which is
mostly of made of glycine(gives silk high tensile strength b/c only has hydrogen in R
group(not sterically constrained), more glycines can form more hydrogen bonds and
make beta sheets)
Nylon = - Synthetic - long fibers - curls, melts, produces black residue, smells like
burning plastic (some sources say it smells like celery?), ignites only when brought into
flame - fine, round, smooth, translucent
Hydrochloric Acid = Hydrochloric acid will react when added to samples containing carbonates--therefore, it is
useful in identifying calcium carbonate, sodium carbonate, and sodium hydrogen carbonate. Calcium carbonate
reacting with generic H2A acid is CaCO3 + H2A -> CaA + H2O + CO2 where CO2 produces bubbles. At 20,
concentrated HCL dissolves catests, tricitrates, saponified cellulose acetate(Fortisan), nylon, silk, rayons slowly.
Lower concentrations dissolve nylon
pH = The pH data for chemicals can be useful, especially for determining between two similar chemicals. Most
samples have a pH of between 5 and 7, but there are several chemicals that have distinct pH's.
Polyester = - Synthetic - fibers can be any length - melts, only ignites when in the flame, drips when it burns and
bonds quickly to any surface it drips on, produces sweet odor and hard, colored (same as fiber) ash - completely
smooth cylinder
Ammonium Chloride flame = faint green flame
Solubility = All samples can be divided into two fields--soluble and insoluble. Water is used to
perform this test.
Soluble Samples = sodium acetate, sodium chloride, sodium hydrogen carbonate, sodium carbonate,
lithium chloride, potassium chloride, calcium nitrate, glucose, sucrose, magnesium sulfate, boric
acid, ammonium chloride
Acetone - At 20, acetone dissolves acetates, tricitrates, modacrylics, and vinyons
Zinc chloride - at 45, 75% zinc chloride dissolves acetates, tricitrates, sil, cotton(not mercerized),
rayons
Non-soluble Samples = calcium sulfate, calcium carbonate, cornstarch
Benedict's solution = Benedict's solution is used to detect glucose. To perform this test, dissolve a small sample of chemical in water in a
test tube. Add two to three drops of Benedict's solution, then place the test tube in a hot water bath. If the glucose is present, the sample will
react and form an orange precipitate. This test may take a few minutes; be patient. An important fact to note is that sucrose will not react
with Benedict's solution but glucose will. Benedict's solution can also be used to test for ammonium chloride. Adding a couple drops will
turn the sample a dark blue. Active component is copper (II) citrate. Available as a ready-to-use reagent. Contains carbonate, citrate, sulfate
makes red, yellow, organ precipitate upon warming with sugar reducing agent. Stable. Indirect positives from sucrose heated with dilute
hydrochloric acid prior to test. Then glycosidic bonds break through hydrolysis.
Potassium flame
light purple, lavender flame
Conductivity = Certain chemical samples will dissociate and become conductive when dissolved in water. To
perform this test, dissolve a small sample of dry chemical in water. Using a 9-volt conductivity tester will
determine whether a sample is conductive or semi-conductive. This data is especially helpful when following a
flowchart.
Ammonium Chloride flame = faint green flame
Polymethyl Methacrylate (PMMA) = Plexiglas, glass substitute
Calcium flame = yellow-red flame
Polystyrene (PS) = Yellow flame • Burns quickly • Plastic drips • Illuminating gas odor (naphtha) • Dense black smoke w/ soot (floating
particles) • CD / DVD jewel cases • Audio and video cassette casings • Model assembly kits • Clear disposable cups • Styrofoam packaging
such as boxes, filler material, etc (EPS) • Styrofoam tableware such as cups, plates, containers, etc (EPS) • Building insulation (EPS) •
Cases for electronic equipment such as television, air conditioner, and computer cases (HIPS) • Stationary such as pen cases, organizing
trays, etc (HIPS) • Toys (HIPS)
Horse Hair = very coarse, thick, medulla is absent to unbroken, cellular or amorphous
(mosaic pattern) imbricate scale on cuticle
Polycarbonate (PC) = • Orange flame • Self extinguishing • Plastic drips • Black smoke w/ soot (floating
particles) • Faint, sweet aromatic odor • Data storage including CDs, DVDs, blu-ray discs, etc. • Lenses including
sunglasses, prescription glasses, automotive headlamps, riot shields, instrument panels, etc • PC is derived from
bisphenol A (BPA) and is no longer used in food applications • Electrical and telecommunications hardware •
Construction materials such as dome lights, sound walls, etc • Automotive, aircraft, and security components •
Medical applications,
Iodine = When iodine is added to cornstarch, the sample will turn black. If cornstarch is not present, the iodine
will remain brown.
Medullary Index = diameter of medulla/diameter of hair
Bat Hair = - very fine - distinguishable by coronal scales on cuticle - looks like a stack of paper cups
Polyvinyl Chloride (PVC) = • Yellow flame w/ green spurts • Plastic does not drip • Self extinguishing • Smells like hydrochloric acid •
Plastic chars • A large usage of flexible PVC is in wire insulation (colored plastic wrapped around electrical wires). Flexible PVC can be
found in clothing such as raincoats, rain boots, and leather-like fabrics. PVCs are also made into vinyl records and vinyl signs and
billboards. • About 75% of all PVC resin (rigid) is made into construction materials such as piping & fittings, siding, flooring, windows,
fencing, decking, roofing, wall coverings, etc
Tests with Liquid = Liquids used for identification are iodine, sodium hydroxide, hydrochloric acid, Benedict's solution, and
water. Not all liquids are applicable to all samples.
Calcium flame = yellow-red flame
Polymethyl Methacrylate (PMMA) = Plexiglas, glass substitute
Low Density Polyethylene (LDPE) Polyethylene Terephthalate (PET or PETE) = • Yellow flame • Plastic drips • Burns slowly • light smoke • Polyethylene
Terephthalate is probably most well known for its use in water, juice, and soda bottles. You’ll also find PET plastic used
in other packaging such as peanut butter jars, containers for holding salad dressings, cooking oils, cosmetics, and household
cleaners. PET used for plastic packaging consumes roughly 30% of PET usage worldwide. • A major use of Polyethylene
Terephthalate is in synthetic fibers used for manufacturing polyester clothing, fabrics, carpets, etc. PET used for this purpose
consumes more than 60% of PET usage worldwide! Mylar is produced from stretching PETE which produces high tensile
strength -> chemical/dimensional stability, transparency, reflectivity
High Density Polyethylene (HDPE)
Chromatography =
There are two types: paper chromatography and TLC (thin layer
chromatography).
Fingerprints = Fingerprints are formed by the arrangement of volar ( pads. They are made
mostly of sweat and water but can also contain various organic and inorganic compounds.
Visible Print = As the name suggests, these ones can easily be seen because they were
made with a substance like ink or blood. They can also easily be photographed without
development.
Reading Mass Spectrogram:1) Search for a molecular ion peak first. It may not always be
present, but it is the peak with the highest m/z ratio. The Nominal Molecular Weight (MW)
is a rounded value assigned to the molecule representing the closest whole number to the
molecular weight. This value is even if the compound being analyzed contains simply
Carbon, Hydrogen, Oxygen, Sulfur, or Silicon. The value will be odd if any of these
elements are combined with an odd number of Nitrogen. 2) Attempt to calculate the
chemical formula, using isotopic peaks and using this order: Look for A+2 elements: O, Si,
S, Cl, Br; Look for A+1 elements: C, N; And then: "A" elements: H, F, P, I. From looking
at the isotopic peaks, it is possible to determine the relative abundance of specific
elements. 3) Calculate the total number of rings plus double bonds: For the molecular
formula: CxHyNzOn rings + double bonds = x - (1/2)y + (1/2)z + 1
4) Try to determine the molecular structure based upon the abundance of isotopes and m/z
of fragments.
Plain Whorl
Double Loop
Radial Loop
Ulnar Loop
Accidental Whorl
RF = distance solute traveled/ distance solvent traveled.
Impression = Made in soft material such as clay. Less easy to detect
than visible fingerprints, but can still be photographed without
development.
DNA = deoxyribonucleic acid
Iodine Fuming = an excellent way to develop prints on flexible, porous and non-porous
surfaces such as paper, index cards, magazines, and cardboard. To fume a suspected latent
print, the surface must be placed into a container with solid iodine. The sublimation of
iodine in a closed container will cause iodine vapors to concentrate, then be absorbed by
the oil and sweat left behind by human skin. The temporarily-developed print will then be
visible as an orange/brown outline. Upon development, the print should be photographed
for documentation. The iodine will eventually sublime from the surface of the print,
allowing the print to return to its latent state. The surface is then returned to its original
appearance and can even be exposed to additional developing techniques.
Ninhydrin = Ninhydrin is a chemical that reacts with amino acids to form a purple compound. This development technique is
used primarily on porous surfaces such as paper, tissue, and clothing. The white powder ninhydrin must be dissolved in
acetone before it can be soaked into a surface for development. The reaction will then develop the print within twenty four
hours, though that time can be significantly reduced if heated, the treated print is heated during development.
Small Particle Reagent (SPR) = Not as common as the other methods
used, but still important. SPR is used for wet surfaces and reacts with
the lipids present in fingerprints.
Cyanoacrylate (Superglue) Fuming = also called superglue method. Most liquid super glues are really either methyl
cyanoacrylate or ethyl cyanoacrylate. Less common types of super glue include butyl cyanoacrylate and isobutyl
cyanoacrylate. Fortunately, all these types of super glue are nearly identical physically and chemically. Super glue reacts with
the traces of amino acids, fatty acids, and proteins in the latent fingerprint and the moisture in the air to produce a visible,
sticky white material that forms along the ridges of the fingerprint. The final result is an image of the entire latent fingerprint.
This image can be photographed directly, or after further enhancement. However, the glue must be in gaseous state. To do
this, one places the surface suspected of containing a latent fingerprint in a container with a heater in it. Then, they place a
small, opened container of the glue on top of the heater, and carefully seal the overall one. After that, simply wait.
gel electrophoresis = When the current runs through the gel during
this process, because DNA is negatively charged, it will move towards
the positive end of the box. Smaller fragments of DNA will obviously
move farther through the gel filter than larger ones.
Glass Fractures
- Cracks end at existing cracks
- A small force forms circular cracks
- Radial cracks and conchoidal cracks make right angles, but face different ways. When
dealing with fractures, remember the 3Rs of glass fracture: Radial cracks at Right angles
on the Reverse side of impact.
- A force very close to the glass before impact, such as a gunshot or a rock, will completely
shatter the glass
Blood Spatters =generally classified by velocity at which they form
four nucleotides = adenine, cytosine, thymine, and guanine Medium Velocity Formation Blood Splatter = A medium-velocity spatter is one that has
a force of anywhere from 5 to 100 feet per second, and its diameter is one to four
millimeters.
It can be caused by a blunt object, such as a bat or an intense beating with a fist. It can also
result from a stabbing. Unlike with a low-density spatter, when a victim is beaten or
stabbed, arteries can be damaged. If they're close to the skin, the victim bleeds faster and
blood can spurt from wounds as his or her heart continues to pump. This results in a larger
amount of blood and a very distinctive pattern. Remember that if a victim is beaten, there
is usually an initial blow which does not result in blood spatter since there is no exposed
blood. Also, medium velocity blood spatters can result from blood being flung from a
weapon that has already hit the victim once, and is now going in for another hit. This forms
a distinctive pattern on the wall which shows the exact movement of said weapon
Low Velocity Formation Blood Splatter = A low-velocity spatter is usually the result of dripping blood. The force of
impact is five feet per second or less, and the size of the droplets is somewhere btwn four and eight millimeters (0.16 to 0.31
inches). This type of blood spatter often occurs after a victim initially sustains an injury, not during the infliction of the injury
itself. For example, if the victim is stabbed and then walks around bleeding, the resulting drops are a type of low-velocity
spatters known as passive spatters. Low-velocity spatters can also result from pools of blood around the body of a victim and
transfers (impressions left by weapons, or smears and trails left by movement). It can occur with some injuries, such as
bleeding sustained from a punch.
Angle of Impact = The angle at which a spatter hits a surface. The
formula for it is:
θ=arcsin(W/L)
Where theta (θ) is the angle, W is the width of the spatter, and L is the
length.
Note that arcsin is also known as inverse sine.
bifurcation
a point on a fingerprint in which a single ridge divides into two
High Velocity Formation Blood Splatter = Classified by blood drops traveling through the air at over a hundred feet per
second, this can appear as either a mist, or a fine spray of droplets btwn .1 and 1 millimeter in diameter (these can help
determine the direction from which the victim was hit).
Blood Types = A, B, AB, O ridge ending = the line-like, raised formations that form the pattern that forensic scientists
use to analyze and identify fingerprints. By all means, they alone with the furrows they
create define the fingerprints. When they form is when a fetus gets his/her fingerprints
(more notes on fingerprint formation are listed below)
Medulla = thin, central structure of the follicle whose function is undetermined. In
forensics, it is important to remember that not all hair follicles found may be human. To
tell the species of origin, forensic analysts look to see the pattern of fractures on the
medulla, if any.
island (short ridge) = formation in which the ridge
is shaped like a dot
lake (enclosure) = an often elliptically-shaped, bowl-like furrow
surrounded by ridges
hook (spur) = one line branching off from the others ridge crossing = two ridges merge then immediately split
opposed bifurcations = opposite "v" shapes on the same line
Cuticle = the external layer of cells resembling a shell of translucent fish scales or a
mosaic. Forensic analysts can use the pattern to determine species of origin and possibly
match the follicle to another human if that's what it is
double bifurcation = Occurs when a ridge splits or
forks into two separate ridges and the splits again
into two separate rides
Trifurcation
Splitting into three branches
cortex
the middle layer of the follicle containing the pigments: made up of a
complex pattern of air pockets, and differently shaped pigment
particles. Forensic analysts take advantage of these unique
arrangements to identify whose hair it is
Luminol (C8H7N3O2)
a white to pale yellow crystalline solid that is solid in most polar organic
solvents, insoluble in water
Loop =
the most common basic pattern of the human fingerprint, formed by
several sharply rising elongated-U-shaped ridges
two types of fingerprint powder
regular and magnetic
Describe the hair follicle of a
caucasian = Shaft diameter:
moderate with little variation, Cross
Section: oval, Pigment granules
evenly distributed
Root = the part of the hair located under the skin (all previously mentioned components of
the follicle are located in the shaft, which is the part sticking out of the skin) in the tube-
like structure known as the follicle. It is where the hair first begins to grow, the underlying
cells forming the protein keratin which comprises the hair.
Describe the hair
follicle of an Asian
= Shaft diameter:
moderate with little
variation, Cross
Section: round, Pigment granules: large patchy
areas
Whorl = one of the basic patterns of the human fingerprint, formed by
several complete circular ridges one inside another
regular powder
preferable when dusting off such surfaces as windows, televisions, kitchen countertops,
magnetic powder
Magnetic powders are best applied to shiny surfaces, such as plastic containers. When dusting for fingerprints with magnetic
