1) Which one of the following lists contains only analytical techniques that can be used to determine the concentration of a substance?
A. AAS, GC and HPLC
B. HPLC, GC and TLC
C. UV-vis and 1H NMR
D. UV-vis, AAS and TLC

Solution

2) A paper chromatograph of four dyes, G, P, R and Y, is shown below.

The Rf value of the dye most strongly adsorbed onto the stationary phase is
A. 0.25
B. 0.33
C. 0.75
D. 0.78

Solution

3) A perfume was analysed using a gas chromatograph. A simplified section of the resulting chromatogram is shown below. The four peaks correspond to compounds P, Q, R and S.

a) What is the retention time, Rt , of Compound Q?

b) All four of the compounds, P, Q, R and S, are from the same family of organic compounds. Which of these four compounds would have the highest molecular mass? State the evidence used.

Solution

c) Using the same instrument on another occasion, it was found that the chemical limonene had a retention time of 53 seconds. Can it be concluded that limonene is one of the compounds in the perfume under analysis? Justify your answer.

Solution