NAME THAT SUBSTANCE MDMAHeroin CocaineMeth MDMA heroin cocaine
Baking soda and powder
Slide 2
Chromatography Separation of Mixtures
Slide 3
What Is Chromatography? A family of laboratory techniques for
separating mixtures into their component compounds Uses some
version of a technique in which two phases, one mobile, one
stationary, flow past one another The mixture separates as it
interacts with the two phases
Slide 4
Basic Principle Different compounds will stick to a solid
surface with different degrees of strength or vary in the
efficiency with which they dissolve in a liquid
Slide 5
Slide 6
Basic Principles A mobile phase sweeps the sample over a
stationary phase like the wind sweeps the swarm over the flower
bed
Slide 7
Basic Principles When a mixture of compounds flows over a
surface, the molecules will stick to the surface If a molecule does
not stick to the surface too strongly, the molecule stick &
unstick many times as it is swept along the surface Over time, the
molecules will become physically separated from each other
Slide 8
Slide 9
Basic Principles When the molecules reach the far end of the
surface, they are detected or measured one at a time as they emerge
Chromatography is non-destructive does not alter the molecular
structure of the compounds
Slide 10
Slide 11
Slide 12
Types of Chromatographic Attraction Adsorption Chromatography
depends on physical forces such as dipole attraction to cause the
molecules to stick to the stationary phase column, TLC, HPLC
Slide 13
Types of Chromatographic Attraction Partition Chromatography
depends on the relative solubility of the mixtures molecules in the
stationary phase coating polarity may also have some effect gas
chromatography
Slide 14
Types of Chromatographic Attraction Size-exclusion the relative
sizes of the molecules determine how fast the molecules move
through the stationary phase large molecules flow right through
small molecules spend time trapped in the pores of the stationary
phase gel filtration chromatography
Slide 15
Types of Chromatographic Attraction Ion-exchange depends on the
relative strength with which ions interact with an ionic resin less
strongly held ions are displaced by more strongly attaching ions
one kind of ion is exchanged for another ion exchange
chromatography
Slide 16
Gas Chromatography Stationary phase a solid or very syrupy
liquid lines a tube (column) silicone polymers (like Silly Putty)
commonly used Mobile phase an inert gas nitrogen helium
Slide 17
Gas Chromatograph (GC)
Slide 18
Slide 19
Slide 20
GC Columns A packed column A capillary column
Slide 21
Slide 22
Schematic of a GC
Slide 23
Retention Time
Slide 24
The time between when the sample is injected & when it
exits the column reaching the detector Tm is the time taken for the
mobile phase to pass through the column
Slide 25
Analysis Using the GC Retention time can be used as an
identifying characteristic of a substance retention times may not
be unique GC is not an absolute method of identification An
extremely sensitive technique area under a peak is proportional to
the quantity of substance present allows quantitation of
sample
Pyrolysis Gas Chromatography Used when sample does not readily
dissolve in a solvent If heating such sample at high temp (500-
1000 0 C) decomposes it into gaseous products, the products can be
analyzed by CGC A pyrogram is obtained
Slide 28
Next Step? Now that you know WHAT is in there (qualitative),
what do you want to know next?