Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Y1 - FAC1 > Chromatography II > Flashcards

Chromatography II Flashcards

1
Q

Describe normal phase chromatography

A

Polar SP/Non-polar MP used

Non-polar analytes don’t interact with SP so elute faster, more polar do interact and separate well

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how does an increase in solvent polarity affect normal phase chromatography

A

Inc in solvent polarity inc solvent strength and dec retention (competition on adsorption sites on silica)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When is the best retention and separation obtained?

A

Using non-polar solvents with low solvent strengths

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe reverse phase chromatography

A

Hydrophobic non-polar SP on surface of solid matrix and polar MP
Polar analytes not retained (elute quickly), non-polar interact with SP so retained/ separated on RP column

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe pH and RPC

A

If analyte neutral, pH of aq MP doesn’t affect separation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the 4 classifications methods?

A

Adsorption, Partition, Ion exchange, Pore penetration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe adsorption chromatography

A

Solid SP where samples adsorbed, Liquid/Gas MP

Compounds distribute btw 2 phases through sorption/desorption processes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe partition chromatography

A

Liquid SP supported on inert solid, Liquid/Gas MP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe what the column in column chromatography may look like

A

Column may be packed with small particles, coated with thin layer of liquid phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe ion exchange chromatography

A

Uses ion exchange resin as SP, separation based on ion exchange equilbria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe size exclusion chromatography

A

Solvated molecules separated by size, depends on ability to penetrate sieve-like structure SP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe thin layer chromatography (TLC)

A

SP - Thin layer on surface of plate, Samples in volatile solvent, evaporated, plate into tank with MP, closed, MP up by cap.ac

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Advantages of TLC

A

Inexpensive, Simple, Easy to detect analytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Disadvantages of TLC

A

More detection limits than HPLC/GC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How to calculate Rf value?

A

Distance travelled by solute/Distance to solvent front

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the 2 types of TLC visualisations?

A

Physical - UV at 254nm

Chemical - I2, H2SO4, pH indicators, Ninhydrin for AA

17
Q

Describe how adjusting MP polarity affects Rf

A

Analytes with stronger interactions with SP have lower Rf values (non-polar)

18
Q

What are the main parts of an LC system?

A

Solvent delivery
Separation column
Detector

19
Q

Describe gas chromatography (GC)

A

Analytes separated btw MP/SP, MP (gas) under pressure flowing through heated column coated with SP (inner column), Column - long tube of silica/metal

20
Q

Which parameters control GC separation?

A

Temp of injector/column
Type/amount of SP
Column size
Type/speed of gas

21
Q

Describe temperature control of GC

A

Sample compounds with similar volatiles separated at same column temp

22
Q

What are the 3 different types of injection systems?

A

Split, Splitless, Cool on-column injection

23
Q

Describe split injection

A

Evaporated sample split so only small portion enters column (best for high conc of analytes)

24
Q

Describe splitless injection

A

Total sample volume injected into column

25
Q

Describe cool on-column injection

A

Direct injection to cold column, sample shouldn’t have non-volatile solvents (may block column)

26
Q

Describe the SP desired product of GC

A

Low volatility, Thermally stable, Chemically inert, Forms thin film

27
Q

Describe the effect of flow rate in GC

A

Broader peak if gas speed is too low/high

28
Q

When is the highest efficiency achieved?

A

By optimum gas velocity

29
Q

Describe the effect of temperature and RT

A

Increase in temp by 30C halves RT

30
Q

What are the 2 types of GC columns?

A

Packed, Capillary

31
Q

Describe packed columns

A

Packed with particles, covered with SP

SP particles fill open tubes, leads to broader peaks

32
Q

Describe capillary columns

A

Metal of fused silica

Open tubes with little pressure drop so can use very long columns without inc in pressure

33
Q

Describe characteristics of the ideal detector

A

Good stability, sensitivity, short response time

34
Q

What are the most common GC detectors?

A

Mass spec detector

Flame ionisation detector

Y1 - FAC1 (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions