CRJU 230 FINAL EXAM (Chemistry, Blood, & DNA Chapters)

Pure vs Non-pure substance

Atom: smallest part of an element and cannot be broken into another substance

Pure substance: have same type of atoms

Non-pure substance: more than two different types of atoms (molecule/compound)

• H20

Three Types of Substances

elements, compounds, and mixtures

Elements: the building blocks which all matter is constructed on an atomic level

• Example: iron (Fe)

Elements make up compounds; for example: Carbon dioxide is the compound and the two elements that make up the compound are carbon and oxygen 

Compounds: substances composed of two are more elements combined chemically in fixed proportions and decomposed by chemical means

• Example: water (H2O) or carbon dioxide (CO2)

Mixtures

Homogeneous mixture: a combination of two or more different substances mixed that are not chemically bonded, in the form of solutions, suspensions, and substance

• Only one state of matter can be present (all liquid or all gas)

• Examples: air or saltwater

  • cannot see the individual components

Heterogeneous mixture: a combination of two or more different substances mixed, not combined chemically, in the form of solutions, suspensions, and substance.

• more than one state of matter can be present (solid and liquid…etc)

• Examples: sand in water or salad

  • different components are visible and can often be separated physically.

Alloys: Alloys are made by mixing metals in different ratios, alloys are mixtures of metals designed to have properties that are more desirable than those of their components.

• Steel: iron + carbon *bonded together by compression 

• Mixed metals 

• Brass: copper + zinc (used for casings) 

• Nickel and aluminum used in guns 

Molecule vs Compound

Molecule: two or more atoms bonded together

• structure; group of atoms bonded

• Not all molecules are compounds

• not visible to humans

• Example: oxygen (O2)

Compound: Two or more different elements bonded together

• structure; matter in complete shape (table salt)

• all compounds are molecules

• visible to humans

• Example: table salt (NaCl)

Periodic Table

Elements are arranged in order of atomic number (i.e., number of protons) instead of atomic mass.

The atomic number gives each element its own unique atomic number. 

• Atomic number: The number of protons or electrons in the nucleus of an atom of an element. *Should be equal 

• The atomic mass number of an element is the sum of protons and neutron

• Periods: seven horizontal rows that divide the periodic table 

• Groups: 18 vertical columns that divide the period table 

There are….

94 natural elements + 24 lab made elements = 118 elements on periodic table

(some are not discovered yet but predicted) *103 discovered 

Metals vs Non-Metals

Metals: 

•  Good conductors of heat and electricity, with a lustrous appearance. 

•  Both ductile and malleable solids at room temperature except mercury. 

• Common metals include sodium, aluminum, calcium, chromium, iron, copper, silver, tin, platinum, and gold. 

Nonmetals: 

• Do not conduct heat or electricity significantly. 

• They have little or no luster and are neither ductile nor malleable. 

•  Common nonmetals include hydrogen, nitrogen, oxygen, chlorine, and noble gases. 

•  Solid nonmetals include carbon, phosphorus, sulfur, and iodine. 

•  Metals are purple, nonmetals are green. 

Semimetals or metalloids:

• boron, conduct electricity well at high temperatures. 

 Semiconductors:

• silicon, germanium, and arsenic conduct electricity better than nonmetals but not as well as metals. 

The Three Classifications of Substances by CH, Bonding, and Formats

Three classifications of substances are:

Chemical Composition (CH), Type of Bonding, and Physical Format

Chemical Composition: two structures of carbon-hydrogen (CH) for Organic (carbon-based) or Inorganic (non-carbon-based)

Bonding: elements and compounds are bond through different chemical bonds

however, Mixtures are not bond chemically instead they are physically combined.

Physical Formats: solid, liquid. gas, plasma

• elements, compounds, mixtures can come in these forms

The Inner Structure of Substances (Protons, Neutrons, Electrons)

• Electrons (-) *negatively charged* circle around the nucleus

• atoms have equal number of Protons (+) positively charged and Neutrons (-+) *neutrally charged * in the core, they balance each other so atoms in core are neutrons (neutral charge) 

• Atomic number: The number of protons or electrons in the nucleus of an atom of an element. *Should be equal *

• The atomic mass number of an element is the sum of protons and neutrons. 

  •  Proton mass equals 1, neutron mass equals 1. (P + N or P x 2), 99.9% of the mass

• Atomic weight: weighted
  average of all isotopes (P’s average)

  
  

• Isotopes: Protons and neutrons are not equal, same carbon property but different atomic mass (neutrons)

• Ion: Protons are not equal to electrons

  • cation (+): when loosing electrons

  • anion (-): when gaining electrons

The Modified Griess Test

• Modified Greiss Test: A test for the presence of nitrites in gunshot residue. 

  • Non-destructive test

  • a color test (pink) of nitrites of incomplete burning of GPR
    residue (size and density)

• Purpose: The test detects nitrite residues from partially burned gunpowder, helping to establish the muzzle-to-target distance. 

• less accurate on unburned powder particles for distance estimation
  

Process:

• Desensitized photographic paper is treated with sulfanilic acid and alpha-naphthol to make it reactive to nitrites

• object (e.g., clothing) is placed face down on the treated paper with the bullet hole centered. 

• back of the object is heated with a steam iron containing dilute acetic acid, causing nitrite residues to react with the chemicals on the paper. 

Result:

• Areas with nitrites appear as orange specks on the photographic paper. 

• This method is particularly useful because it doesn’t interfere with subsequent tests for lead residues and provides clear visual evidence of nitrite presence. 

Gunpowder Residue: made of nitrocellulose

Four Types of Gunpowder

Flakes, Discs, Balls, and Cylinders

Flakes: (75%) not shiny

Discs: shiny

Balls: shaped like tiny balls

Cylinders: rifles usually have it

The SEM Examination

Scanning Electron Microscopy (SEM)

• analyzes both GPR and GSR

• Advantage: Its collection method for GSR is easy to carry out in the field; CST just applies an adhesive tape directly to the suspect’s hands (or other surface) to lift the GSR. 

•  Limitation: Too sensitive (can be transferred to one person to another) if you shake shooters hand it will detect the GSR on your hand 

Sample Collection: 

• The GSR sampling kit includes tubes with aluminum stubs that have an electrically conductive adhesive layer. 

• The investigator removes the cover from the stub and dabs it over the suspect’s hand to collect GSR particles. 

• The stub is then covered again, and the tube is labeled for identification. 

• In the lab, the forensic examiner places the stub into a scanning electron microscope for detailed analysis. 

GSR vs GPR

• Gunshot Residue: made up of Lead, Antimony, Barium (found in primer) *Inorganic 

• GSR can be found near thumb area *yellow color 

  • GSR is a perishable type of evidence: delay in obtaining residues (valuable up to 8 hours), movement, or washing of the body prior to autopsy may diminish or destroy GSR.  

  •  Simply washing the hands will remove the GSR. 

• Gunpowder Residue: Nitrocellulose or Nitroglycerin (Unburnt or Burnt Powder) *Organic (carbon-based) 

• GPR Usually lands on person’s clothing or skin *black color 

  • Unburned powder, semi-burned powder (bigger than unburned), burned powder (soot) 

• Different types of gunpowder: Flake, discs, cylinder (rifle usually has this one) ball 

• Black Powder= Potassium Nitride Charcoal and Sulfur (IED) 

• Contact vs. Distance Estimation (soot density, distribution shape and size) 

• Helps determine shooting distance  

  • Shooting distances 

    • Contact

    • Close (3-6 inches)

    • Medium (6-12 inches)

    • Longer (>18 inches)
      

Organic vs Inorganic Materials

• Organic Material: (carbon-based) and living thing (carbon-hydrogen = CH)

  • Example: cane sugar 

  • GPR is organic

• Inorganic Material: (non-carbon based) not produced by living things

  • Example: metal 

  • GSR is inorganic

• Pure Water (H2O) does not have carbon element and is an inorganic substance.

• 
  * In forensic settings: Dirty water in a victim’s lung or mouth is a mixture.

  • If it
    contains any fatty, juice, vegetables, microorganism, proteins, or lipids for carbohydrates it is then an organic substance (during body decomposition)

Combustion Ring vs Abrasion Ring

• Abrasion ring: black ring around the bullet wound, oil and powder put together (star torch shape) 

  • formed when the force of the gasses entering below the skin surface back against the muzzle of the gun (contact range wounds) 

• Combustion Ring: around the entrance wound, reddish-bluish bruising  

  • occurs when shot close range *more useful to CST’s*

These occurrences help determine the SHOOTING DISTANCE!!!

Burned vs Unburned Powder vs Soot vs Stippling

• Burned: created when the gunpowder ignites and burns during the firing process

• Unburned Powder: consists of gunpowder particles that did not ignite during the process

• Stippling: little circles around bullet wound, embedded into skin or clothing *tattooing 

  • consist of unburned powder particles

  • occurs when shot at contact to close range

• Soot is a black powdery or flaky substance consisting largely of amorphous carbon, produced by the incomplete burning of organic matter. 

  • It’s commonly found in areas where combustion occurs, such as chimneys, engines, and industrial processes. 

Particles vs Micrometer

• Particles: small fragments or pieces of material that can be collected from a crime scene.

  • Example: GSR (using SEM)

  • Example: dust, fibers, glass fragments, soil, etc..

• Micrometer: a unit of measurement you get from multiplying by one million meters

  • used to measure thickness or size of small objects and particles

  • In length; millimeter (mm) *Micromillimeter (AM) + 1000, nanometer (9ng) 

Quality vs Quantity Analysis

•  Qualitative analysis confirms the presence of an element or molecule. 

  • A qualitative analysis may determine whether white powder found at a crime scene involving a poisoning contains arsenic or is powdered sugar, as the suspect claims.  

•  Quantitative analysis determines the compounds present and their concentrations. (measures how much)

  • A quantitative analysis, by contrast, determines the compounds present and their concentrations. 

  • Example: Blood Alcohol concentration test

Video: Gunshot Residue Test

1. What is the key question on the form for the investigator to ask a potential suspect? 

   1. If they have recently shot a fire arm?..because if the answer no and later the results test positive for gunshot residue then it's hard for them to come back from denying it at first (makes them have to explain why they lied) 

2.  Where was the GSR mostly likely located? 

   1. The GSR is most likely located in the back thumb area of your hand  

3. How does the GSR test differentiate a suicide and homicide? 

   1. You test the suicide victims' hands for GSR and if it tests positive then that helps investigators confirm that it was a suicide not a homicide made to look like a suicide 

4.  What are the three limitations of the GSR test? 

   1. Needs to be done recently, AS SOON AS POSSIBLE suspects can wash hands and will wash away any GSR, putting hands in pockets etc...(GSR disappears after 8 hours) 

   2. if there is a struggle the victim could have GSR on them  

5.  Where was the video produced? 

   1. Indiana University of Pennsylvania (Department of Chemistry), presented by Sergeant Anthony J. Clement and the Indiana Borough Police Department 

 

Hands on (GSR vs GPR) different types of gunpowder shapes + GSR and GPR color on casing

Flakes: flat and thin not a specific shape, look like cereal flakes

Discs: look like tiny cd’s, a more circular shape

Balls: shaped like mini balls

Cylinder: look like mini cylinders

GSR is a yellow color on casing when looking at it through a microscope

GPR is a black color on casing when looking at it through a microscope

Types of Bloodstains

• Passive bloodstains are formed by the influence of gravity.  

• Active bloodstains are formed by blood that has traveled by a force other than gravity. 

•  Transfer bloodstains result from contact with wet blood.  

• Bloodstain pattern analysis is used to establish what occurred during a violent crime and to elucidate the probable sequence of events

The Major Components of Human Blood and its Testing Steps

• Erythrocytes: Red blood cells allow you to determine Blood type (ABO type) 

  • four blood types: A, B, AB, O

  • 60% 

  • contain hemoglobin, the iron-containing protein that carries oxygen (gives you) (and takes away carbon dioxide). 

  • do not have nucleus

• Leukocytes: White blood cells carry DNA!!! in the nucleus 

  • 5% - 10% or even less 

  • They protect the body from infection. 

• Thrombocytes: platelets.

  • Platelets are non-nucleated cell fragments that form in the bone marrow.  

  • How much platelets determine how fast a cut heals 

  • They are involved in the blood clotting mechanism. 

The Principles of Luminol and Seratec Tests

Luminol test: that can detect the iron in blood from mixes as low as 1-to-1-millions mixtures

• highly sensitive! and will detect small traces of blood 

• needs a dark setting and UV lighting

• Dark blue for a “positive”

• DNA destructive

• highly likely for false positive (contains iron) 

Seratec test: reacts to human hemoglobin only

• turns a purple color for positive

  • C only =negative 

  • T only = invalid 

  • C + T = positive  

  • T bar color varies—ag and concentration 

• German product, can determine aged blood (31-32 years)

  No need for dark setting or UV light

• 4 products: Saliva, Blood, Semen, menstrual blood

  • Non-destructive on DNA

The ABO Typing System

• ABO Typing System: Classifies human blood into four categories based on presence or absence of antigen A or B. 

• Type A (42%) 

• Type B (12%) 

• Type AB (3%): has both A and B antigens or master receiver 

• Type O (43%): has neither A nor B antigens or called master donator  

Forensic value: can be used to go back to parent's blood type which can help identify suspects blood type and determine whether the suspect has been correctly identified or helps narrow down the suspect pool 

The Principle of the Pythagorean Theorem on the Blood Angle Calculation

The Pythagorean Theorem states that in a right-angled triangle, the square of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides.

• should equal up to 180 degrees

the Pythagorean Theorem helps determine the angle at which blood droplets hit a surface.

equation is: [ c^2 = a^2 + b^2 ]

• c is the hypotenuse

• a and b are the other two sides

Blood Angle= D/d ….

The Principle of Saliva (Paper) and Semen (Test Kit) Tests

Saliva can be found in discarded items like cigarette butts, chewing gum, water glasses, or bottles at crime scenes 

The presence of salivary amylase by Seratec is a positive presumptive test for saliva (fluid +paper test)

• A blue-black solution indicates starch, a negative test for saliva. 

• A yellow solution indicates salivary amylase breaks down starch into smaller sugars. 

The presence of seminal stain by Seratec (3 bars) as a positive presumptive test

Erythrocytes vs Leukocytes Cells

• Erythrocytes: Red blood cells allow you to determine Blood type (ABO type)

  • four blood types: A, B, AB, O

  • 60%

  • contain hemoglobin, the iron-containing protein that carries oxygen (gives you) (and takes away carbon dioxide).

  • do not have nucleus

• Leukocytes: White blood cells carry DNA!!! in the nucleus

  • 5% - 10% or even less

  • They protect the body from infection.

Non-Human Blood vs Non Blood Samples

• Non-human blood sample = animal blood (cow, pig, chicken, etc.) *sheep blood closest to human blood 

• Non-blood sample= red paint, ink, ketchup 

Presumptive vs Confirmatory Tests

• Presumptive test: is done in the field, so the evidence is fresh less contamination

  • based on preliminary result can make arrest

  • can begin plea bargain (defendant pleas guilty and avoids a trial in return for a lenient sentence) *cannot appeal once plea guilty 

• Confirmatory test: (final test), second test by advanced techniques like the precipitin test 

Luminol vs Hemident vs Blue Star vs Seratec Tests

• Luminol: needs a dark setting and UV lighting, iron reactive 

• Hemidnt: reacts with iron in blood 

• Blue star: Dutch product and based on Luminol, spray that doesn’t need a dark setting or UV lighting, Hemoglobin reactive (animal blood will not work) 

• Seratec: German product, can determine aged blood (32 years), 4 products: Saliva, Blood, Semen, menstrual blood, Hemoglobin reactive  

Hemoglobin vs Iron Element in Blood

Hemoglobin is a metalloprotein found in red blood cells.

Iron is a metal ion and an essential micronutrient.

Hemoglobin is a complex protein, while iron is a simple metal ion.

Sine (θ) vs Arcsine (Sin-1) vs Cosine

Angle of blood = d/D(shorter dimension/longer dimension); then use table to find angle

False Positive vs False Negative Tests on Blood

• False positive = innocent person in prison 

  • Test comes out positive when it should have come out negative 

  • Example: Animal blood being tests positive for human blood 

  • More dangerous because after exoneration comes a very expensive lawsuit 

• False Negative = guilty person walks free 

  • Test comes out negative when it should have come out positive

• Positive control= use a source you know for sure is going to be positive 

  • Example: Testing blood you know is human blood, while testing for human blood 

• Negative control uses a source you know for sure is going to be negative

   

Type A, B, AB, O Blood Types and Their Test Results

• Type A (42%) 

  • Test result: A or O

•  Type B (12%) 

  • Test result: B or O

•  Type AB (3%) 

  • Test result: A , B , AB, or O

  • Universal recipient

• Type O (43%) 

  • Test result: only O

  • Universal donor

Spurt/Gushing vs Expiated Bloodstains

• Spurt / Gushing: from a blow to an artery *main blood source

  • (low velocity) beer bottle, punch 

• Expiated: from mouth or nose 

  • low velocity so “satellite” splatter

Splatter vs Spatter vs Mist/Projected vs Cast-Off

• Splash: medium (pipe or club) blunt object no sharp edge  

• Spatter: smaller (lower) velocity (knife) 

  • could be from stabbing

• Mist/projected: very small dots and V-shaped 

  • from gunshot wound 

• Cast – off: when a bloody object swings blood onto other surfaces  

Video: Seratec

• What is the PSA for? The PSA is for the detection of seminal fluids  

•  What is the HemDirect for? Detects Blood  

• What is the PMB for? Detects menstrual blood (fewer red and white cells *dying cells) 

• What is the Amylase for? Detection of salvia (DNA can be tested) 

•  Which reagent has a paper testing form? Amylase filter paper for detection of latent saliva stains  

Hands on Different Types for Blood

Blood Visual  

• Yellow solid stains on clothes from ketchup  

• Blood is yellow brown color on clothes because it penetrates the fabric and changes color 

• Red stain that does not change color, stays bright red that is ink 

• Yellow liquid stain is from juice 

• Black shoelace; blood will stay reddish color and not change to yellow brown 

• A victim under fingernail can have many sources of evidence like: hair, blood, and skin cells 

The Brief DNA History

• James Watson and Francis Crick at University of Cambridge were the first to describe the DNA structure (double strand helix) and a method of replication in 1953.

• In 1983, Dr. Alec Jeffreys discovered a region in human
  DNA (< 0.1%) that showed enormous variations from one
  person to another, now known as DNA fingerprinting (de-
  oxyribo-nucleic acid)

  • talking about spacers!

• Sir Jeffreys first applied it to two murder cases in 1985 in
  Leistershire, U.K. semi-successfully.

The DNA Roadmap (Six Steps)

1. Human Genome

2. Chromosome= (23 pairs, 46 chromosomes in total)

3. Gene= a region of DNA that helps determine a characteristic

4. Locus/loci = a specific spot on each chromosome occupied by repeats and varying by individuals

5. Alleles = number of repeats

6. DNA Coding/Profile = letter sequence method or allele method (number of repeats)

The Pitchfork Syndrome

Colin Pitchfork was a British serial killer who raped and murdered two teenage girls in the 1980s.

His case became famous because it was the first time DNA evidence was used to convict a criminal, thanks to Alex Jefferys

• The Most likely suspect was local youth Richard Buckland. 

  •  DNA samples from Buckland and the girl's body did not match. 

•  Police took DNA samples from 5,000 men over six months, but no matches were found. 

•  Ian Kelly, who gave his sample while masquerading as a friend, was taken into custody. 

  •  Pitchfork, a local baker, was taken into custody and matched his DNA to the killer. 

•  Pitchfork later confessed to both murders. 

The Two DNA Comparison Methods (The Sequential Order and the Allele)

Letter sequence method: using base pairs

• T bonds with A

• G bonds with C

Alleles Method: number of repeats (CODIS)

• number of repeats at each locus from two parents for (13 pairs, 26 total chromosomes)

The Supreme Court Decisions on DNA examination

• 50 states require that DNA samples to be collected from
  those convicted felonies.

• 28 states and the federal government currently collect DNA
  samples from arrestees for serious crimes (felony) from a
  2013 Supreme Court case.

More Issues:

• Convicted misdemeanors?

• Arrestees of misdemeanors

• Exoneration Requirement

  • Requires original police station to have original DNA from case 

• Locations (Admissibility)? Home, Apartment/Condon,&
  Curb

• Regulations on Genealogy

  • Violent Crime only (Murder and Rape)

  • Exhausted as last resort

  • No arrest/CODIS

The Coded Gene vs Non-Coded Gene

Nucleus is coded with protein

• In cell, have nucleus, in nucleus 23 pairs of chromosomes (46 in total) 

  • Nucleus DNA pinpoints exact individual 

• 13 chromosome pairs used by CODIS FBI 

  • 26 individual chromosomes in total 

• Outside nucleus is mitochondria (only gives you maternal DNA *all children from same mother) 

Spacers (non-coded) 

• > 0.1% 

• T bonds with A 

  • Two hydrogen bonds 

  • 60% 

• G bonds with C 

  • Three hydrogen bonds 

  • 40% 

• Called JUNK DNA but very important to CST’s 

Genome vs Chromosome vs Gene

Genome 

• Entire family (genes, spacers, loci, alleles, and base pairs) 

Chromosome 

• Inside the nucleus 

• 23 chromosome pairs (46 in total) 

• 4-30 repeats  

Gene 

• Coded with protein not important only need Spacers!

Locus/Loci vs Alleles

• Locus: one  

• Loci: plural 

• Alleles: number of repeats 

TA vs GC Base Pair Rule

TA vs GC Base Pair Rule 

• Tom marries Ann (T bonds with A)

  • two hydrogen bonds

  • 60%

• George marries Cathy (G bonds with C)

  • three hydrogen bonds

  • 40%

The Letter (Sequential) Order vs The Alleles Methods

The Letter Order 

• Using T, A, G, C to represent you DNA sequence (old) 

Alleles Method 

• Uses the number of repeats (ex: 7:9) 

• Heterozygous alleles: two peaks from two different alleles from the parents 

• Homozogous alleles: one peak from the two identical alleles from the parents 

PCR vs STR

STR 

• Short tandem repeat: Current STR are 26 loci on 13 chromosomes on the spacers that contain a short segment (400 bases) with repeated sequences of bases up to around 30 times/repeats (allele) 

• STR is less likely to degrade, but quick for amplification 

• Higher discrimination power (more detail more discrimination*good kind)

  • the U.S database requires the 13 loci with two alleles to match per locus under the CODIS 

PCR 

• Allows use to produce DNA profile as long as you have one letter (because of base pair rule)

  • Ex: only have T well T only bonds with A so you found the missing letter 

    •  Polymerase chain reaction (PCR): A reaction that is used to make millions of copies of a section of DNA. 

    • Advantages: PCR amplifies only those DNA regions that are of interest; it ignores all other regions in the DNA strand. PCR is fast and, because it can make copy after copy, extremely sensitive.

n-DNA vs f-DNA; m-DNA vs Y-DNA

N-DNA vs F-DNA  

• N-DNA 

  • nucleus DNA

• best DNA it is more accurate but requires a nucleus  

• F-DNA

  • Partial or Familal DNA 

    • have 13 loci and only 11 out of 13 or 12 out of 13  

    • Real suspect is not far away (family related) 

M-DNA vs Y-DNA 

• M-DNA 

  • mitochondria DNA (1,000 copies) 

  • less accurate get a group of potential suspects not one 

• Y-DNA 

  • focus on Y chromosome DNA (for gang rape situations etc..) 

  • only males have Y chromosome 

CODIS vs NGI vs Forensic Genealogy

CODIS: FBI DNA database 

• requires 13 pairs of chromosomes to match, 26 individual chromosomes

NGI: replacing CODIS (New Generation Identification) combining all 7 databases that the FBI has currently     

 

Genealogy: using third party DNA database (23 and me) which will narrow down the suspects family tree, can go up to fourth generation cousin!!!

• Grim Sleeper 

• Golden State Killer 

 

Genotyping vs Phenotyping

• Genotype: n-DNA genetics, help pin down suspect 

• Phenotype: Based on Genotype + environmental conditions  

  • Dominant and recessive (competing between Mother and Father) 

  • Produces eye color, hair color, skin color, height (strong) 

  • Personality (medium) 

  • Behavior pattern (low) 

  • Allow forensic scientist to predict suspect profile 
     

Degradation vs Cross-Contamination vs Mutation

• Degradation: evidence is being disqualified and damaged (lower quality for you to use) 

• Cross-Contamination: unintentional *forget to change gloves etc... 

  • Training problem 

• Contamination: unwanted (something added) *bystander could contaminate 

  • Contamination could be intentional  

Mutation  

• Mutations can cause an error in your DNA sequence 

  • Example: G pairs with T which does not abide by base pair rule 

• Based on location of mutation can determine family relation  

Video: Introducing DNAscan Rapid DNA Analysis System

1)The Rapid DNA device takes about 85 minutes to test up to 5 samples simultaneously. 
 

2) How many times the person needs to swab his/her inner cheeks in the first time? 

- 6 times up and down inside the cheek 
 

3) Why need to take a second swab as a reference sample and store it up? 

-allows user to store samples for later use or send to lab for further analysis 

• useful for exoneration cases
   

4) What are the three steps/measures to guarantee the COC in the Rapid DNA process? 

- 3. RFID chips  

- 1. Access samples and machine with username and password 

-2. barcode label on sample tubes 

 

5) Three limitations? 

- only can be used to exclude a suspect, determine they are the wrong person 

- still need to do a PCR test to verify and include a suspect, determine they are the suspect 

- need a credential to use this device, training for this machine 

Hands on

Type of Swabs for DNA (Blood, Semen, and Saliva) 

• Regular cotton swab 

  • Cotton tip is inexpensive 

  • Weaker absorption  

  • Need a container 

  • Likely contamination 

• Cotton swab connected to container 

  • Foam/sponge tip 

  • More absorption 

  • Tube protection 

  • Serial number 

  • Write-in space 

• Flock trip (cotton cloth) 

  • For cheek swab 

    • Semi-covering 

      • Write-on space 

        • Cut ready for use 

• Swab for only saliva (swab mouth, then DNA is transferred to tab and placed into a machine) 

  • Form + Flock tip 

  • Two: Swab + Container 

  • Larger area more absorption 

  • Card semi-auto punch 

  • Barcode + DNA ready