4. Analytical Techniques

Chromatography — Quiz

Test your understanding of chromatography with 5 practice questions.

Practice Questions

Question 1

In gas chromatography, why is an inert gas such as helium or nitrogen used as the carrier (mobile) phase?

Question 2

Given a compound in GC has a retention time $t_R=5.0\,\text{min}$ and the dead time $t_M=1.0\,\text{min}$, what is the capacity factor $k$?

Question 3

Using the Van Deemter equation $H = A + \frac{B}{u} + C\,u$, calculate the height equivalent to a theoretical plate $H$ (in mm) for a column with $A=2\,\text{mm}$, $B=1\,\text{mm}\cdot\text{cm/s}$, $C=0.05\,\text{mm}\cdot\text{s}$, operating at a linear velocity $u=5\,\text{cm/s}$.

Question 4

In an HPLC chromatogram, a peak for compound X has a retention time $t_R=4.50\,\text{min}$ and a baseline width $w=0.15\,\text{min}$. What is the number of theoretical plates $N$?

Question 5

For two peaks in HPLC with $t_{R1}=2.00\,\text{min}$, $t_{R2}=2.60\,\text{min}$ and each baseline width $w_1=w_2=0.10\,\text{min}$, what is the resolution $R_s$?