Chapter 22-24 Separations

Question 1

The process in which we separate compounds from one another by passing a mixture through a column that retains some compounds longer than others.

Extraction

Answer 1

chromatography

Question 2

a substance that stays fixed in the column

a substance or solvent that moves through the column

Answer 2

stationary phase

mobile phase

Question 3

Stationary Phase:

Can be ____ or _____ tubular.
A ____ liquid _____ to the ____ of a tube
_____ particles are _____ inside a column.

Mobile Phase:.
Solvent entering the column is called _____.
Stuff leaving the column is called _____.

Answer 3

open, packed
viscous, bound, inside
solid, packed

eluent
eluate

Question 4

Adsorption Chromatography:

___ stationary phase and a ____ or _____ mobile phase.

Solute is ______ on the surface of the solid particles.

The more ______ a solute is adsorbed, the _______ it will travel through the column.

Answer 4

solid, liquid, gaseous

adsorbed

strongly, slower

Question 4

Adsorption Chromatography:

___ stationary phase and a ____ or _____ mobile phase.

Solute is ______ on the surface of the solid particles.

The more ______ a solute is adsorbed, the _______ it will travel through the column.

Answer 4

solid, liquid, gaseous

adsorbed

strongly, slower

Question 5

Partition Chromatography:

A______ stationary phase is bonded to a ______ surface.

Typically the inside of the _____ (SiO2) column for _____ chromatography.

Solute ______ between the stationary liquid and mobile phase (flowing gas in GC).

Answer 5

liquid, solid

silica, gas

equilbrates

Question 6

Ion-Exchange Chromatography:

Anions or cations are ______ attached to the stationary _____ phase, usually a _____.

Solute ions of the opposite charge are ______ to the stationary phase.

Mobile phase is a _____

Answer 6

covalently, solid, resin

attracted

liquid

Question 7

Molecular Exclusion:

Also called:
____ exclusion
Gel ____
Gel _____

_______ by size, with ______ solutes passing through ____ quickly.

____ in a gel are small enough to ____ large solute molecules but not _____ ones.

Small take ____ to pass through because the enter the gel and flow through a _____ ______

Answer 7

size, filtration, permeation

seperating, larger, most

pores, exclude, small

longer, larger volume

Question 8

Affinity chromatagraphy:

Most ______ type because it employs ____ interactions between one kind of solute molecule and a second molecule that is _______ attached to the stationary phase.

An ____ and a ____.

Analyte flows through and the stationary phase _____ to it, _____ it until the end.

Eventually there is a ___ or ___ strength change ____ it from the stationary phase and _____ the column .

Answer 8

selective, specific, covalently

antibody, protein

attached, holding

pH, ionic, detaching, leaving

Question 9

Chromatography Theory:

Mobile phase flowing through the column has a rate.

Answer 9

flow rate (mL/min)

Question 10

Graph showing the detector response as a function of elution time.

Time that elapses between injection of sample and arrival of that component at the detector.

The time is takes for mobile phase to travel through the column.

Basically the “blanking” of chromatograms.

Answer 10

Chromatogram

Retention time (Tr)

retention mobile phase (Tm)

adjusted retention time (t’r)

Question 11

Ratio of the adjusted retention times.
- The greater the relative retention, the
greater the separation between two
components

Time required to elute that peak minus the time for the mobile phase to pass through the column, expressed in multiples of tm.
- The longer a component is retained by the
column, the greater is the retention factor

Answer 11

Relative Retention (separation factor)

Retention factor

Question 12

Two factors contribute to how well compounds are separated:

The difference in ____ ____ between peaks.
Farther ____ the better.

How ____ the peaks are.
The wider the peaks, the ______.
The wider the peaks, the _____ the solute ____ on the column.

Answer 12

elution times, apart

broad
poorer separation, longer, stayed

Question 13

What are the two places peaks are measured in?

a quantitative measure of how well two elution peaks can be differentiated in a chromatographic separation.

Answer 13

Baseline (w)
half weight (w1/2)

Resolution

Question 14

Resolution ___ 1.5 is desirable

Answer 14

greater

Question 15

A band of solute ______ as it moves through a chromatography column.
- Ideally a band should be ____ in shape.

One main cause of band spreading is ______.
- Net transport of a solute from a region of ____ concentration to a region of ____ concentration caused by ______ movement of molecules.

Answer 15

broadens, Guassian

diffusion
- high, low, random

Question 16

The height of one plate in a column.
- _____ the better.

Place where solute molecules equilibrates between mobile and stationary phases.
- The _____ plates the better.

Answer 16

Theoretical plate height (H)
- smaller

Theoretical Plates (N)
- more

Question 17

Doubling the column length ______ resolution by √2.

Resolution _____ as the unadjusted relative retention _____.
- Change _____ of species through column.

Answer 17

increases

increases, increases
- velocity

Question 18

Plate height is ______ t the variance of a chromatographic band.

The ____ the plate height, the ____ the band.

_______ ________ tells us how the column and flow rate affect plate height.

Answer 18

proportional

smaller, narrow

van Deemter equation

Question 19

H = A + B/ux + Cux

A: 
- will be \_\_\_\_ in open tubular 
B:
- how \_\_\_ does it \_\_\_ in the colum?
C:
- How \_\_\_\_\_ is the solute to the stationary phase?

Answer 19

A - eddy diffusion/multiple paths 
- zero 
B- longitudinal diffusion 
 - long, stayed 
C - equilibration time/Mass transfer 
- attracted

Question 20

B: longitudinal diffusion

the more it moves down the band th