Forensic Chemistry Exam 3

Trace Evidence

wide range of materials such as plastics, polymers, paints, paper, hair, fiber, soil, tape and gunshot residue.

Microanalysis

Evaluation (both quantitatively and qualitatively) with goal of identification of minor or ultra minor components of the sample.

Physical Properties of trace evidence

dentist, magnetism, size, diameter, morphology, fracture edge matching, and refractive index.

Chemical Properties

% composition, pH, spectroscopic properties and elemental composition.

Immersion Method

pieces of glass, fiber, soil minerals are immerses into liquids/oils of its own refractive index. When refractive index of the sample is equal to the liquid, ,match point has been reached.

Becke Line

halo glow that appears around an object immersed in liquid.

Match point

when unknown evidence and known liquid have the same refractive index.

Locard’s Exchange Principle

Whenever two objects come into contact, a transfer of material will occur. Trace evidence that is transferred can be used to associated objects individuals or locations.

Glass Analysis Points

• High or low velocity impact

• differentiation of color, thickness, texture, uniformity, curvature and fitting pieces together

• refractive, reflective, fluorescence and density properties.

Glass

hard, amorphous, brittle transparent solid. Can originated from windows and exhibits conchoidal or smooth rounded fractures.

From SiO2, other chemicals can lead to varying colors and properties.

Radial Fractures

Initial impacts in non-tempered glass leads to formation of radial fractures that emanate from break point

Concentric Fractures

Circular lines that spear to form a circle around point of impact or between radial lines.

Conchodial Lines or Hackle marks

arch shaped stress markings are perpendicular to one glass surface and curved parallel to the opposite surface. Perpendicular lines are on the side of origin.

Tools for Glass analysis

Microscope with Hot stage, SEM, SEM with x-ray spectroscopy, LA-ICP-MS, EDS, XRF

Absorption

taking in of alcohol or other substances through the skin, oral mucosa, stomach or intestine into the bloodstream

Excretion

elimination of metabolic waste products from body

Ingestion

taking in food or substance

metabolite

a product from the breakdown of a substance in the liver or other organs

Secondary Metabolite

a product or molecule produced by humans, animals, bacteria and fungi that is not required from its normal, growth, development or reproduction leading from the ingestion of poisons or other substances.

Toxicology

the science of the identification and quantification of poisons and their clinical effects.

forensic toxicology

focused on the identification and quantification of legal and illegal substances to answer questions pertaining to violations of criminal law.

ethanol

-CH3CH2OH

-alcohol

-in pure form it colorless liquid.

Blood Alcohol Concentration(BAC)

-maximum concentration of alcohol in the blood

-registers at minimum 30 mins

-can be altered by many factors like weight, food, ect.

Absorption Rate

affected by the time taken to consume the alcoholic drink, it alcohol content, number of ounces consumed, body weight and tolerance of individual ect.

Post- absorption period

beings when BAC begins to decline

Alcohol metabolism

pathway the alcohol is broken down by ADH pathway.

Alcohol Dehydrogenase-Acetaldehyde Pathway

-coupled with respiratory chain in mitochondria

-Ethanol—>Acetaldehyde

NAD+—→NADH

Aldehyde Dehydrogenase Pathway (ALDH)

Acetaldehyde—→acetic acid

NAD+—→NADH

Acetic acid produced goes to Krebs Cycle which energy can be broken down into energy, CO2, and Water

Alcohol Deterrent Drug

Block the activity of functional ALDH2 enzyme serving as inhibitors.

Intoxilyzer

determines BAC via evaluating the absorbance of infrared light captured by breath determined by a detector. Measured BAC indirectly by decrease in light transmitted if alcohol present

Breathalyzer

-Ethanol reacts with potassium dichromate reagent under acidic conditions and using AgNO3 catalyst- Chromium sulfate product is detected via spectroscopy

Fuel Cell Method

determined BAS using alcohol as a fuel that is ignited and burned in the Prescence of oxygen creating energy created to electric current.

Evidence to collect near potential overdose

-pills or powders

-paraphernalia

-empty pill containers

Retention Time

Length if time a drug may be found in body fluid

-varies differently between dose, specific body fluid, metabolism ext.

Analytical Scheme

it detects, isolate, and identify poisons, drug substance and their metabolites.

Metabolites of Heroin

6-acetyl morphine—>morphine

Metabolites of Codeine

Hydrocodone—>hydromorphone of dihydrocodeine, morphine, norhydrocodone

Fiber

a natural or synthetic textile that is long thin capable of being spun into yarn.

multilobal

a synthetic textile fiber with multiple strands, includes tri/penta lobal fibers