High Performance Liquid Chromatography

Question 1

What was high-performance liquid chromatography developed from?

Answer 1

Gas chromatography

Question 2

What is done to the substance being analysed during HPLC

Answer 2

The substance being analysed is added to a liquid solvent (mobile phase)

Question 3

What is the mobile phase in HPLC?

Answer 3

A liquid solvent

Question 4

What is done to the liquid phase in HPLC?

Answer 4

It is passed over very fine silica particles (stationary phase)

Question 5

What acts as the stationary phase in HPLC?

Answer 5

Very fine silica particles

Question 6

Why are very fine silica particles used as the stationary phase?

Answer 6

It was discovered that better separation of the components of the mixture occurs if the particles in the stationary phase are very small

Question 7

What is the issue with using very fine particles in the column during HPLC?

Answer 7

The liquid passes very slowly through the column

Question 8

The liquid passes very slowly through the column during HPLC, what is done to combat this?

Answer 8

A pump is used to force the liquid through the column

Question 9

What is the solvent reservoir?

Answer 9

This is a large bottle of the liquid solvent used which is drawn out using a pump

Question 10

What is chromatography in which a pump is used to force a liquid through a tightly packed column called?

Answer 10

High-performance liquid chromatography

Question 11

What is high-performance liquid chromatography?

Answer 11

Chromatography in which a pump is used to force a liquid through a tightly packed column

Question 12

What is the principle of high-performance liquid chromatography?

Answer 12

A liquid mobile phase is in contact with a stationary phase (fine particles of a solid) and separation of the mixture occurs as a result of selective adsorbance of the components of the mixture on the stationary phase

Question 13

What are the five processes involved in the use of the HPLC instrument?
(5)

Answer 13

Injection of sample containing the mixture

Pumping if sample along the column

Separation in the column

Detection of components of mixture

Display of results

Question 14

Why does the column not need to be as long in HPLC than in GC?

Answer 14

Since separation is more efficient in HPLC

Question 15

What is the column made of in HPLC?

Answer 15

Stainless steel

Question 16

Why does the column need to be made from stainless steel?

Answer 16

To withstand the high pressure of HPLC

Question 17

What are the advantages of HPLC over GC?

2

Answer 17

It is carried out at a lower temperature than GC so it can be used to analyse compounds that would decompose at the high temperature needed for GC

It is particularly suited to analysis of mixtures of compounds that are non-volatile and this unable to be separated by gas chromatography

Question 18

What is HPLC commonly used in?

5

Answer 18

To test for the presence of growth promoters in meat

To test for vitamins in food

To test for additives in food

To measure the concentration of alcohol in blood

To measure the concentration of caffeine I’m drinks

Question 19

What may HPLC be used in conjunction with?

Answer 19

Mass spectrometry

Question 20

Why may mass spectrometry be used in conjunction with HPLC?

Answer 20

To aid the identification of compounds