science olympiad forensics event hints, tips, things to prep

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

pocket

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