science olympiad forensics event hints, tips, things to prep
TRANSCRIPT
Science Olympiad
Forensics Event
Hints, Tips, Things to Prep
What’s New Each team member may bring notes Bunsen burner PS (polystyrene) limited to non-expanded Fingerprints
8 NCIC classifications development techniques
DNA PCR (not cell division)
Blood type ABO avian vs mammalian vs reptilian
Overview Story arc presents
suspects types of evidence which exhibit goes w/ which suspect
exhibit list
Table of Results in notes?
Crime Scene
Suspect 1
Suspect 2
Suspect 3
Su
sp
ects
Evidence
Powder Fiber HairPoly Gr 2 Gr 2
P1
P2
P3
P4
R1
R3
R4
R2
Prep the Team Divide the responsibilities Trust each other Person 1
start the chromatogram powder tests
Person 2 prep the Table of Results polymers hair fibers
Make the "Notes" page 8½" x 11 "
allowed 2 sheets this year hand written there are 2 sides to a sheet of paper…
Table of Test Results dichotomous keys
entomology flowcharts for tests
polymer density
Make the "Notes" page tables of expected results
powders which test yields which positive indication
distinguishing characteristics hair fibers glass
formulas Rf
spatter
Prep Pack the "Kit"
see list in Rules ex: thermometer
non-mercury (safety clause) does not specify analog or digital
ex: test tubes… or any devise in which they can perform tests plural test tubes spot plates, well plates have enough to run all tests w/o washing waterproof box for dirty stuff
ex: paper towels plural does not specify all the same type pack plenty (include enough for cleanup)
Categories of Exemplars Powders Polymers Fibers Hair Chromatography
Any 2(R), 3(S), 4(N) of fingerprints DNA glass entomology spatter seeds & pollen tracks & soils blood type bullet striations
Prep - Powders Develop a Flowchart
Practice the tests chart of results in "Notes" count equipment needed for "Kit"
Soluble Iodine Test
HCl Test
Flame Test
Cornstarch
Calcium Carbonate
Calcium Sulfate
Pos
Electrolytic
Yes
Benedict'sNo
Glucose
SucroseNeg
No Pos
Pos
pHmild acid Ammonium
Chloride
Yes
HCl Test
vinegarsmell
Sodium Acetate
base
CO2 Test
no smell
pH<10 Sodium Hydrogen
Carbonate
Sodium Carbonate>10
Yes
Sodium Chloride
Calcium Nitrate
Lithium Chloride
Potassium Chloride
yellow/orange
red/orange
crimson
purple
Flame Test
No
Magnesium Sulfate
yellow
no effect
Boric Acid
Flame Testfaint green
blue/green
Prep - Polymers Burn Test Results
Polymer "Burn" Behavior
PETE Bubbles; slow burn; soot; pungent
HDPE Fast burn; clean; drips flames; white smoke
LDPE Fast burn; clean; drips flames; white smoke
PS Fast burn; lots of black soot
PP Slow burn; some drips flame
PVC Melts more than burns; self-extinguishing
PMMA Bright flame; no smoke
PC Slow burn / smolder; no smell; self-extinguishing
Prep - Polymers Density Dichotomous Key
Water46%
Isopropyl AlcoholVegetable
Oil
10% NaCl
SaturatedNaCl
PP LDPEHDPE
PS
PETE PVC
PC PMMA
Unknown Polymer
floats
sinks
floats
floats sinkssinks
floats
sinks
sinks
floats
Prep - Fibers Microscopic Examination
cotton – twisted flat ribbon
wool – hair; imbricate scales
Prep - Fibers Microscopic Examination
silk – double ribbon
linen - bamboo
Prep - Fibers Microscopic Examination
nylon - tri-lobe cross-section
polyester - round cross-section; delustering pits
Fibers – Burn Tests Burns AsbestosNo
Self-Extinguishing
Yes
Chars
No Yes
Burning GrassGrey Ash
Linen
Melts
Burning PaperGrey Ash
Cotton
Vinegar OdorHard Black Ash
Acetate
Burning MeatHard Black Ash
Rayon
Tumeric OdorSoft Black Ash
Acrylic
Chars
Burning HairSoft Black Bead
Silk
Melts
Burning HairDark Ash
Wool
Celery OdorHard Grey Bead
Nylon
Sweet SmellHard Black Bead
Polyester
Prep - Hair Human
Medullary index < 1/3 even distribution of pigment
Human Hairs
Hair Cross-Section
Prep - Hair Animal
Medullary index > 1/2 Dog
continuous medulla scales usually not visible ovoid bodies root is spade-like
Prep - Hair Animal
Medullary index > 1/2 Cat
uniserial medulla; very large spinous scales root looks frayed
Prep - Hair Other Stuff to Know
cuticle scale patterns coronal (crown like) imbricate (flat; think shingles) spinous (petals; think asparagus tips)
medulla patterns (Nationals) trace discontinuous continuous uniserial ladder multiserial ladder amorphous (bubbly)
Prep - Chromatography How to "run" a chromatogram How to measure Rf
Rspo t d ist
fron t d istf
Prep - Chromatography Typical chromatograms
Prep – Mass Spectroscopy Consider affinity area under curve % concentration
Optional - Fingerprints arch
tented
arch
loop radial ulnar
Optional - Fingerprints whorl
central
double
loop
accidental
Optional - Fingerprints Minutia
bifurcation trifurcation ridge island dot delta
Optional - Fingerprints Detection
powder cyanoacrylate fuming
amino acids, fatty acids, proteins non-porous surfaces
iodine fuming fats, oils porous surfaces noxious, corrodes surfaces
silver nitrate salts
ninhydrin amino acids kills living tissues
Optional – DNA Chromatogram
• PCR – DNA copy machine
Option - Glass Index of Refraction Hot-Stage Microscope Stress Lines Order of fractures
Option - Entomology Time Lines
Blow Fly larva maggot pupa adult
Beetles usually arrive after blow flies
Option - Spatter Directionality Angle of Impact Droplet Size
sin w id th o f sta in
leng th o f sta in
Option – Seeds, pollen visual microscopic comparison
Option – Tracks visual comparisons directionality
Option – Soils compare composition microscopic examination soil triangle
Option – Blood Type ABO blood type
perform antigen tests RBC, WBC, platlet human vs avian vs reptilian
Option – Bullets comparison of striations
Science Olympiad
Forensics Event
Hints, Tips, Things to Prep