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Lecture 29

CHEM 212 Lecture Notes - Lecture 29: Size-Exclusion Chromatography, Gas Chromatography, High-Performance Liquid Chromatography


Department
Chemistry
Course Code
CHEM 212
Professor
Hamilton M.Coreen
Lecture
29

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Chem 212!
Nov. 16/2016!
!
Chromatography!
a bunch of liquid liquid separations!
seperation technique!
two immiscible phases!
more versatility --> two phases !
stationary!
mobile!
Gas chromatography -> moving phase gas!
Liquid chromatography --> liquid moving phase!
sample infused into mobile phase!
Each small interaction with stationary phase has its own partition coecient!
the column is either gas or metal!
gravity chromatography --> not much pressure therefore use glass!
need metal when more pressure !
stationary phase is packed particles !
pressure is applied so movement is induced!
Instrumental technique column is on its side!
!
!
mobile phase$$$$$$$$$$out$$$$$$$$$$Collection or Detection!
!
!
!
!
size of peak from instrument gives us quantitative data!
also gives us qualitative --> from when it appears out of column!
!
How does separation occur:!
sample is introduced before the column --> put into mobile phase!
mobile phase goes past the stationary phase!
compound interacts with the stationary phase dierently for each compound!
component of mixture that interacts more with the stationary phase is last to come out of column!
the compound that interacts the most will spend the most time in the column and will come out on the graph last!
retention time!
x-axis gives time!
y-peak height!
!
Types of chromatography:!
-adsorption!
-partition!
-ion-exchange!
-size exclusion !
-anity chromatography!
!
Adsorption!1.
polarity interaction!A.
sample components and surface of the stationary phase interact!B.
all non-polar components wash off!a.
change solvent gradually to higher and higher polarity to coax them o the stationary phase!b.
most polar are still attached!c.
all the way to methanol and water to get most polar solvents to coax off!d.
the smaller the particles in the stationary phase the better the interactions, therefore the better the e.
separation. Once particles get too small though, the solvent won't go through anymore --> apply
pressure HPLC!
Partition !2.
Sample components do not adsorb onto surface but actually dissolve!A.
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