Ion Exchange Chromatography
The first exercise preformed in this lab was ion exchange chromatography. The purpose of this experiment is to separate molecules based on their differences in charge. Since it is based on charge the amino acids in the cation exchange column, if negatively charged, flow through the column first because they don’t want to bind to the sodium ions. The positively charged ions will elute last at the highest ph because they bind to the negatively charged beads. This way of thinking is how the predictions in table 3.1 were made. Each fraction for each ph was placed on its corresponding filter paper strips. The darkest color fraction is the one that is picked to be used on the TLC paper, giving the experimenter three fractions. For ph 3.5 the 6th fraction was used out of the 11 1ml samples taken. For ph 6.5 the 5th fraction was used out of the 25 samples, and for the 10.5 the 6th was used also out of 25 fractions.
These fractions were then put onto TLC paper with the four known amino acids to confirm that there is a separation of amino acids. The distance up the TLC paper was measured and values were calculated by taking the distance traveled by the substance over the distance traveled by the solvent. These values were compared to those of the known amino acids and the values that related closest to the fractions were its related amino acid. These results coincide with the predictions made earlier further showing the relation to charge.
In conclusion, the results of this lab were as predicted and proved it to be an overall successful experiment. Some possible sources of error could occur when moving the fractions from the column to the test tube. If not moved at the correct interval the wrong amino acid could be in the wrong fraction because the column is not stopped during this process. Another possible source of error would be with the TLC paper. The known amino acids only had to be spotted three times because they...
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