Name _______________________________________
HONORS FORENSIC SCIENCE
ORGANIC ANALYSIS
I.
II.
III.
IV.
Elements and Compounds
a. Matter = anything that has mass and occupies space
b. Element = cannot be broken down into simpler substances by chemical means
i. Listed on periodic table
ii. 98 naturally occurring elements
c. Periodic Table = chart of elements arranged in a systematic fashion
i. Vertical rows are called groups or families
ii. Horizontal rows are called series
iii. Elements in a given row have similar properties
d. Atom = smallest particle of an element that can exist and still retain its identity as that
element
e. Compound = a pure substance composed of two or more elements
i. 6 million known compounds
Physical states
a. Solid = rigid and has definite shape and volume
b. Liquid = occupies specific volume, but fluidity causes it to take shape of container it is in
c. Gas (vapor) = neither definite shape or volume
d. Substances change from one state to another
e. Sublimination = physical change from the solid directly into the gaseous state
f. Phase = a uniform piece of matter, different phases are separated by definite visible
boundaries; ex. Oil and water
Selecting an Analytical technique
a. To select technique, need to know whether substance is organic or inorganic
i. Organic = substance composed of carbon and hydrogen
ii. Inorganic = CO2 and all substances that lack carbon
iii. Also, need to consider the need for qualitative or quantitative determination
Analytical Techniques
a. Spectrophotometry
i. An analytical method for identifying a substance by its selective absorption of
different wavelengths of light
ii. Most applicable to organic analysis
iii. Optimum utilization requires that a material be in relatively pure state
b. Chromatography
i. Any of several analytical techniques whereby organic mixtures are separated
into their components by their attraction to a stationary phase while being
propelled by a moving phase
ii. Useful technique for purifying substances
iii. Behavior first observed in 1803 by William Henry (Henry’s Law)
iv. During process, one phase is always made to move continuously in one direction
over a stationary or fixed phase
v. Is like a race between chemical compounds; at beginning, all substances are
mixed together; a race progresses, those that have preference for moving
phase will move faster and pull ahead of others; at end, all substances
separated
vi. Gas Chromatography
1. Separates mixtures on the basis of their distribution between a
stationary liquid phase and a moving gas phase
2. Used widely because of its ability to resolve a highly complex mixture
into its components within a time period usually measured in minutes
3. Is very sensitive
4. Sample must be vaporized and passed through heated tube
vii. High-performance Liquid Chromatography
1. Liquid is moving phase
2. Can perform process at room temperature
3. Used for organic explosives and drugs that are heat sensitive
viii. Thin-layer chromatography
1. Incorporates solid stationary phase and moving phase to effect
separation of constituents of mixture
2. Because most compounds are colorless, use UV light to reveal those
that fluoresce
3. Cannot be itself provide absolute identification; has to be used in
conjunction with other procedures to prove absolute identity
4. Powerful tool for solving analytical problems
5. Rapid and sensitive
6. Minimal cost and space requirements
ix. Electrophoresis
1. Related to TLC in that it separates materials according to their migration
rates on solid phase
2. Uses electrical current instead of moving liquid phase
3. Characterization of proteins, enzymes, and DNA