Once the stationary phase is packed in the column, it is important that the solvent level not drop below the upper level of the stationary phase. Why?
A. Air molecules are so polar the entire mixture moves completely through the column.
B. If the stationary phase dries out, then the mixture will be permanently absorbed.
C. Air creates channels that may cause all of the components of the mixture to travel down the column at the same rate.
D. Atmospheric moisture can dissolve the stationary phase.
The correct answer is C. Air creates channels that may cause all of the components of the mixture to travel down the column at the same rate.
Explanation: In chromatography, the stationary phase is the substance that is packed into the column and interacts with the components of the mixture being separated. The mobile phase, on the other hand, is the solvent that flows through the column and carries the components of the mixture with it. The interaction between the stationary and mobile phases determines the separation of the components.
When the solvent level drops below the upper level of the stationary phase, air can enter the column and create channels. These channels allow the solvent to bypass the proper paths for separation, causing all of the components of the mixture to travel down the column at the same rate. As a result, the separation of the components becomes ineffective, and the desired separation cannot be achieved.
To prevent this, it is important to ensure that the solvent level remains above the upper level of the stationary phase. This keeps the column properly saturated with the solvent, preventing the formation of air channels and maintaining the effectiveness of the separation process.