You're likely referring to the context of thin-layer chromatography (TLC), a technique commonly used to separate and visualize amino acids. Here's why the amino acid spots should not be submerged in the solvent:

* Solvent front: The solvent acts as the mobile phase in TLC. It travels up the stationary phase (TLC plate) carrying the amino acids with it. If the spots are submerged, the solvent will immediately saturate the entire spot, leading to poor separation as the amino acids will be dissolved and carried along the entire length of the plate rather than being separated according to their individual affinities for the stationary phase.

* Contamination: Submerging the spots can lead to the dissolution and contamination of the amino acids in the solvent. This can create inaccurate results and make it difficult to visualize the spots.

* Distortion: Submerging the spots can distort the shape of the spots, making it difficult to accurately measure their Rf values (the distance traveled by the spot relative to the distance traveled by the solvent front). This can lead to inaccurate identification of the amino acids.

Proper Procedure:

In TLC, the amino acid samples are spotted above the solvent level on the TLC plate. The plate is then placed in a developing chamber containing a solvent system. The solvent front rises up the plate, carrying the amino acids with it, resulting in their separation based on their properties.

In summary, keeping the amino acid spots above the solvent level in TLC ensures proper separation, prevents contamination, and allows for accurate identification.