Amino acid content in orange juice

... investigated using chromatography.

Task: Determine which amino acids are present in orange juice using chromatography.

Method:

1. On a piece of silica paper, draw a horizontal pencil line a few milimetres above the level of the solvent which you will put the paper in.

2. Draw 4 points on the line and label them according to the amino acids used and orange juice (OJ). I used leucine (LEU), lysine (LYS) and asparagine (ASP).

3. With a capillary tube, transfer a small amount of each sample on the labelled points. Use one capillary for each sample to avoid cross-contamination. Repeat this once more after the drops had dried.

4. Put the dry silica paper in the frame and secure it with a rubber band.

5. Using a pipette, put a mixture of propanol and amonia into the reservoir. Do not let the solvent reach the pencil line. Put the frame into the reservoir.

Frame with silica paper in reservoir.

1. After 45 minutes, take the paper out, apply a chemical with fixing agents in it and bake the paper in the oven. Coloration of the amino acids will appear.

2. Compare the level to which the orange juice rose up to with the levels of the amino acids.

Results:

Final levels of aminoacid samples and the level the solution rose up to.

Conclusion: Orange juice might contain lysine or asparagine. It might not contain leucine.

Evaluation: The staining of the orange juice is not clearly visible on the silica paper, therefore I could not surely determine the results. To improve this I would apply more concentrated drops of samples, about 4 drops per spot. Cellulose paper also seemed to work better than silica.