i need a lot of help with this instrumental analysis questions a-d With referenc
ID: 922547 • Letter: I
Question
i need a lot of help with this instrumental analysis questions a-d
With reference to specific chromatographic equations, explain how each of the changes described below would affect the plate height (H) and retention time (tr) for a solute, if any, while everything else about the system is held constant.
a. increasing the weight of a stationary phase on the inner walls of a capillary gas chromatography
b. increasing the flow rate in gas chromatography
c. Reducing the particle size of the packing material in a liquid chromatographic column
d. decreasing the column temperature in a supercritical fluid chromatography
Explanation / Answer
(a): Increasing the weight of the stationary phase increases the volume and hence the interaction of solute particles with the stationary phase becomes easier. Hence retention time and plate height increases.
(b): When the flow rate is increased, the interaction time of the solute particles(components) with the stationary phase decreases. This gives a poor separation and hence the retention time and plate height decreases.
(c): Reducing the particle size of the packing material in a liquid chromatographic column reduces the volume. Hence retention time and plate height decreases.
(d): Decreasing the column temperature decreases the speed and randomness of the solute particles to be separated. This makes the interaction of the particle with the stationary phase easier. Hence the retention time and plate height increases.
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