Question
Transcribed Text
1. Explain briefly the general principle of sample separation by chromatography.
2. Give the three equations required to calculate R--values, the CV and the ACV.
3. An unknown sample has been applied to 4 different TLC plates. Each TLC plate has been runi in a
different mobile phase. The stationary phase of the TLC plates is made of unmodified silica gel.
.
@
A
c
D
acetone/toluene
unknown
unknown
1:6
1:3
system
system
Complete the table using the TLC plates above.
A
B
c
D
cv
cv
cv 3
-
-
ACV 2
ACV3
4. Consider the results obtained in the table under task 3. Summarise your observations and discuss
these interms of the quality of the sample separation.
5. Consider the system used in TLC A;Ethanol/CH_Cl, 1:6.
a) Which TLC will show a larger change in the R: values, a change to a Ethanol/CH2CI2 1:7 system or
Ethanol/CH_CI, 2:6?
b) Why? Explain briefly.
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Answer 1: Chromatography is used to separate sample mixture by their continuous distribution between two phases that is stationary and mobile phase.There are four general principle of sample separation by chromatography, these are adsorption (sample is separated between solid stationary and liquid or gaseous mobile phase on the basis of polarity difference of individual component of sample), partition (sample is separated between liquid stationary and liquid or gaseous mobile phase on the basis of difference in partition coefficients of individual components), ion exchange (sample is separated between solid stationary ion exchange...
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