Organic AnalysisHonors Forensic Science

I. 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 in 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

II. 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

III. Selecting an Analytical Technique A. To select a 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 and quantitative determination

IV. Analytical Technique

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 the beginning, all substances are mixed together; as 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 by 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