Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
35 Cards in this Set
- Front
- Back
|
partition coefficient
|
K=Conc of Solute in phase 2/conc in solute in phase 1
*the larger the p.c the less solute remains in phase 1 |
|
|
Fraction remaining in phase 1 after n number of extractions
|
q=(V1/V1+KV2)^n
*many small extractions better than one large |
|
|
solubility of charged and uncharged species
|
neutral-soluble in organic
charged-soluble in aqueous |
|
|
Distribution coefficient
|
replaces K when dealing with a species that has more than one from (ie B and BH+)
Acid->D=K[H+]/[H+]+Ka Base->D=K(Ka)/Ka+[H+] |
|
|
chromatography
|
same principle as extraction but uses a mobile phase and a stationary phase
|
|
|
mobile phase
|
usually either a liquid or a gas, the mobile phase is the solvent that is moving through the column
|
|
|
stationary phase
|
usually a viscous liquid bonded to the inside of the column
|
|
|
goes in/goes out
|
elueNt(iN) eluATE(evacuATE out)
|
|
|
types of column
|
packed
open tubular |
|
|
adsorption
|
solute adsorbed on surface of stationary phase
|
|
|
partition chrom
|
solute dissolved in liquid phase bonded to the surface of column
|
|
|
ion-exchange chrom
|
anions vs cations
|
|
|
molecular exclusion chrom
|
large molecules excluded, small molecules penetrate pores
|
|
|
affinity chrom
|
used in cancer research, stationary phase covalently bonds to passing molecules
|
|
|
volume flow rate
|
how many mL solvent per min travel through column
|
|
|
linear flow rate
|
how many cms traveled by solvent in 1 min
|
|
|
chromatogram
|
graph showing detector response as a function of elution time
|
|
|
retention time
|
time needed after injection until the component reaches the detector
shower example |
|
|
retention volume
|
the volume of mobile phase required to elute a solute from the column
|
|
|
capacity factor
|
k'=tr - tm/ tm
|
|
|
adjusted retention time
|
tr'=tr-tm
adjusted retention time is also called station time or ts and refers the time the solute spends in the stationary phase |
|
|
mobile phase
|
is the part of the solvent that moves through the column, tm refers to the amount of time spent in the mobile phase
|
|
|
extraction
|
transfer of solute from one phase to another, used to isolate or concentrate desired analyte
|
|
|
stationary phase
|
the phase that stays in place in the column, ts=time spent in stationary phase=tr-tm=tr'
|
|
|
longitudinal diffusion
|
diffusional broadening of a band that takes place along the axis of the column, occurs while band is transported through column by solvent
|
|
|
resolution
|
difference in tr/w(avg)
or difference in vr/w(avg) or 0.589(diff in tr)/w1/2(avg) |
|
|
diffusion coefficient
|
measures the rate at which a substance moves randomly from a region of high concentration to lower concentration
|
|
|
plate height
|
H=L/N
small plate height=more plates=narrower peaks=better separations |
|
|
relative retention
|
alpha=tr'2/tr'1=k2'/k1'=K2/K1
physical basis of chrom |
|
|
separation factor
|
gamma=t2/t1=u2/u1
|
|
|
silanization
|
reduces tailing by blocking hydroxyl groups with nonpolar trimethylsilyl groups
|
|
|
van Deemter equation
|
H~A+B/Ux+CUx
A=doesn't exist in open tube, multiple path term, Eddy diffusion B is opposite of C so need to find balance between two |
|
|
gas chromatography
|
mobile phase-gas
stationary gas-usually nonvolatile liquid, sometimes solid analyte-gas or volatile liquid |
|
|
Carrier Gas
|
He, H2, N2
He-most common |
|
|
open tubular column
|
more common
|
