Failed questions of 2021-01-11 exam not including mass spectrometry

Question 1

b. Explain what chemical tailing is in chromatography. What causes the tailing to occur and what type of compounds (analytes) suffers from this phenomenon? (2p)

Answer 1

Tailing occurs when free sialnol groups create hydrogen bonds with the analyte. Polar compounds often experience tailing like alcohols, amines and carboxylic acids.

Question 2

What is meant with isothermal analysis?

Answer 2

Having a constant temperature during the analysis

Question 3

You want to develop an isocratic normal-phase HPLC method for the separation of ethylbenzene () and ethyl benzoate () a. Propose a suitable stationary phase and a suitable mobile phase. (2p)

Answer 3

Silica as stationary phase and a mixture of two organic compounds as mobile phase (for example tolune, hexane or chrloroform)

Question 4

GC : True or false, The retention factor increases if the film thickness is decreased.

Answer 4

False

Question 5

True or false, e. HPLC : the plate height decreases with decreased particle size

Answer 5

True