Forensic Chemistry and Toxicology

Forensic chemistry - is the application of chemistry to criminal investigation. Focuses on the chemical analysis of substances connected to a crime.

Forensic Science - is the use of science and technology to enforce civil and criminal laws.

Blood - a specialized body fluid that circulates in the arteries and veins of vertebrate animals, carrying oxygen to and carbon dioxide from the tissues.

Semen - the male reproductive fluid containing spermatozoa in suspension.

Moulage - is the art of applying mock injuries for the purpose of training emergency response teams and other medical and military personnel.

Methods of Identifying Unknown Substance
  1. Gas Chromatograph-Mass Spectrometer - useful
      method for the simultaneous separation,
      identification and quantization of one or more
      individual components of an unknown substance or
      mixture.
  2. Spectroscopy - is the study of the interaction
      between matter and radiated energy.

Spectrophotometer - instrument used to aide in the identification of compound.

Gas Chromatograph - a chemical analyzer and instrument for separating chemicals in a complex sample.

Mass Spectrometry - is the analytical technique that measures the mass to charge ratio of charged particles. It is used for determining masses of particles.

Amino Acid - the building blocks of protein coded by triplets of bases of DNA blue print.

Ammonia - a colorless gaseous alkaline compound that is very soluble in water, has characteristics of pungent odor, is lighter than air and is formed as a result of the  decomposition of most nitrogenous organic material such as tissue from dead bodies.

Anemia - any condition in which the number of red blood cells, the amount of hemoglobin and the volume of packed red blood cells per 100 ml of blood are less than normal. It may result from increased destruction of red cells, excessive blood loss or decreased production of red cells.

Aplasia - failure of an organ or tissue to develop normally.

Autolysis - the destruction of cells after death due to lack of ability to metabolize oxygen needed by enzymes for cell activity.

Hair - any of the fine threadlike strands growing from the skin of humans,mammals, and some other animals.

What are the 3 stages of hair growth?
1. Anagen phase - the growth phase.It begins in
    the papilla and can last up to 8 years.The span at
    which the hair remains in this stage is determined by
    genetics.The longer the hair stays in the anagen
    phase,the faster and longer it will grow.About 85%
    of the hair on one's head are in this stage at any
    given time.The hair has a follicular tag.The root bulb
    is flamed shaped.
2. Catagen Phase - also known as the transitional
    phase,allows the follicle to renew itself.During this
    time which last about 2 week,the hair follicle shrinks
    due to disintegration and the papilla detaches and
    rests,cutting the hair strand off from its nourishing
    blood supply while hair is not growing during this
    phase.The length of the terminal fibers increase
    when the follicle pushes them upward.The root is
    elongated.
3. Telogen phase - or resting phase,the hair and
    follicle remain dormant anywhere from 1 to 4
    months,10% to 15% of the hairs in one's head are
    in these phase in any given time.The anagen phase
    begins again when this phase is complete.The root
    is club shaped.

Shedding - the process of normal hair loss.

Alopecia - a hair loss disease that causes the hair to spontaneously fall out.It is mainly characterized by bald patches on the scalp or other parts of the body and can ultimately cause baldness across the entire body.

Medulla - inner most layer of the hair shaft.

From which part of the body are most often used for hair comparison? Either head or pubic.

How to determine the likely race of the person from which a hair originated?
1. Caucasian - evenly distributed,fine pigmentation
    Wavy with round cross section.
2. Mongoloid - Continuous medullation.
3. Negroid - dense,uneven pigmentation.

Rate of speed of hair growth - 1.25 cm or .05 inches per month or about 6 inches or 15 cm. per year.

What aspect of the hair is the criminalist interested in matching?
1. matching color
2. Length
3. Diameter
4. presence or absence of medulla
5. distribution,shape,and color intensity of the
    pigment granules in the cortex.

What types of evidence found at the crime scene are most likely to provide evidence? Forcible removed hair are most likely to provide useful DNA evidence because they often bear follicular tags that are sources of nuclear DNA.

Hair from different parts of the body vary significantly in its physical characteristics.

Forensic Toxicology - deals with the medical and legal aspects of the harmful effects of chemicals on human beings.

Forensic - comes from the Latin word "forensis" meaning forum.

Toxicology - from the Greek word toxicos - "poisonous" and "logos".
                   - it is the study of the symptoms, mechanisms and treatments and
                     detection of poisoning.

Poison - a substance that when introduced into or absorbed by a living organism causes death or injury.

Toxin - an antigenic poison or venom of plant or animal origin especially one produced by or derived from micro organisms and causing disease when present at low concentration in the body.
         - poisonous substance produced during the metabolism and growth of certain micro organism and some higher plant and animal species.

Venom - poisonous fluid secreted by animals and typically injected into prey by biting or stinging or other sharp body feature.

Acute Poisoning - is exposure to poison on one occasion or during a short period of time.

Chronic Poisoning - is long term repeated or continuous exposure to a poison where symptoms do not occur immediately or after each exposure.

Antidote - a medicine taken or given to counter act a particular poison.
               - a substance which can counteract poisoning.

Mathieu Orfila - is considered to be the modern father of toxicology, having given the subject its first formal treatment in 1813 in his "traite des poisons" also called toxicologie generali.

Dioscorides - a Greek physician in the court of Roman emperor Nero, made the first attempt to classify plants according to their toxic and therapeutic effect.

Jean Stas - a belgian analytical chemist who in 1850 gave the evidence that the Belgian count Hypolite Visart de Bocarme killed his brother in law by poisoning with nicotine.

Celsus - a roman physician from the first century, considered the father of toxicology. He is credited with the toxicology maxim "all things are poison and nothing is without poison. This is often condensed to "the dose makes the poison" or in latin "sola dosis facit venenum".

Paracelsus - "Theophrastus Phillipus Aureleus Bombastus von Hohenheim (1493-1541) - believe that his studies were above and beyond the work of celsus.

LD50 - is the dose required to kill half the members of a tested population after a specified test duration.

Dose - a quantity of medicine or drug taken or recommended to be taken at a particular time.

Overdose - the ingestion or application of a drug or other substance in quantities greater than are recommended.

Carcinogen - any substance capable of causing cancer in living tissue.

Corrosive substance - is one that will destroy or irreversibly damage another surface or substance with which it comes into contact.

Related Readings: Forensic Chemistry
1. Forensic Chemistry Reviewer 1
2. Forensic Chemistry Reviewer 2