Medicine - Chromatographic Techniques Flashcards Preview

Pharmacy Year 2 Semester 1 > Medicine - Chromatographic Techniques > Flashcards

Flashcards in Medicine - Chromatographic Techniques Deck (31):
1

Uses of chromatography

Analyse
Identify
Purify
Quantify

2

Common features of chromatography

All have a stationary phase (solid or liquid supported by a solid)
And a mobile phase (liquid or gas)
The mobile phase flows through the stationary phase and carries the components of the mixture with it. Different components travel at different rates dependent on their attraction to the mobile phase and the stationary phase

3

What is meant by development when referring to chromatographic techniques?

Elution

4

What is the solute referred to as?

The euate

5

What is the mobile phase referred to as?

The elluant

6

Describe the process of column chromatography in 5 steps

1 - load the stationary phase material into the column
2 - Equilibrate column stationary phase with the mobile phase
3 - Load sample in as small a volume as possible
4 - Add more mobile phase to the column
5 - Collect sample fractions from the column

7

What are the two possibilities of substance the column can be loaded with in terms of mobile and stationary phases? (In column chromatography)

The column is either loaded and filled with mobile phase, which is then flushed through the column,
Or
More usually, loaded with a slurry of stationary phase and mobile phase together (care taken to avoid bubbles)

8

When is sand used in column chromatography?

Sand is used if cotton wool is used in place of a sinter disc

9

Describe how molecules of analyte are separated in column chromatography in terms of stationary and mobile phases

Molecule with high affinity for the stationary phase will take longer to travel through the column.
Thus, molecules of different polarities separate out

10

Stuff to monitor in normal phase chromatography and how to monitor it

Monitor fractions:
-colour
-weight
-TLC
-derivatives
-spectroscopy

11

What one factor determines the type of chromatography it is?

The type of solid/stationary phase determines the type of chromatography

12

Most common stationary phase in normal phase chromatography? Give particle sizes

Silica gel (Si-OH) is mostly commonly used
-40-63um particle size
-high surface area (~800m2/g)

Alumina is less commonly used
50-200um particle size

13

Describe how use of column chromatography as a purification tool would happen in 4 steps

1) Collect fractions
2) Determine component of interest by methods such as colour, TLC, UV, fluorescence
3) Pool fractions
4) Column can then be washed with eluting solvent and re-used or discarded

14

Use of chromatography in laboratories and in industry?

Used to separate an purify compounds on scale from mg to kg

15

What is the stationary phase in TLC?

Usually silica, but alumina and cellulose are used too

16

What does TLC stand for?

Thin layer chromatography

17

What is the driving force in TLC?

Mobile phase moves through stationary phase by capillary action

18

What is the elutropic series?

A scale of compounds starting at high polarity (water, acetic acid) down to low polarity (cyclohexane, n-hexane)

19

What is flash column chromatography used (a lot of the time) for?

Gas separation

20

In flash column chromatography, what affects solvent flow? Discuss

Particle size affects solvent flow
70-230 silicia gel for gravity columns
Smaller particles (higher mesh values) need a pump to flow the mobile phase

21

Describe the instrumentation in flash column chromatography

Solvent reservoir
Pump (causes fast elution, can use gas instead)
Column
Detector (fraction collector)
Recorder

All of this is in a closed system

22

Elution expected in order of organic classes for flash column chromatography?

Increasing polarity (more slow)

Saturated hydrocarbons
Unsaturated hydrocarbons
Ethers
Esters
Halides
Ketones
Aldehydes
Amines
Alcohols
Acids and bases

23

Name 7 uses of TLC

-Quality control and purity evaluation
-synthetic chemistry for identifying compounds
-To select a solvent system for column chromatography
-To follow the progress of a reaction
-To follow purification process
-Basic identity to check on pharmaceutical raw materials
-Detect impurities in pharmaceutical raw materials and formulations

24

What interactions go on in TLC and normal phase chromatography?

Weak polar interactions i.e.
Dipole-dipole
Hydrogen bonds

25

Name the specific stationary phase used sometimes in TLC to detect things with no colour

F254 = fluorescent reagent (shine UV light and it looks green)

26

Name some ways you would detect colourless components when doing TLC

-UV light
-chemical treatment (dip, spray) e.g. Ninhydrin
-chemical vapour e.g. Iodine

27

TLC colour for UV light (indirect)

Dark spot on yellow/green background

28

TLC colour for iodine vapour

Brown
Spraying with starch makes it permanent

29

In TLC, what does potassium permanganate detect?

Sugars and sugar-like molecules

30

What colour spot does Ninhydrin cause in TLC? What is it used to detect?

Purple/pink spot with amines
Used for gentamycin

31

What colour does alkaline tetrazolium cause in TLC when it detects something? What does it detect?

Blue spots with corticosteroids