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Rf Value

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Rf value is expected between 0.2 -0.8 and all my data was in that range (prefer to table 1 and table 2). In figure 1, the TLC plate shows that the phenylalanine traveled longest distance (4.0cm), and it also had a largest Rf (0.67) value compared to other amino acids. This is because it is less polar hence less interacts with stationary phase, so it moved farther. The Lysine traveled shortest distance (1.8cm) and the Rf value was 0.30, which indicate lysine is the most polar compared to other amino acid. It was interacted more with the stationary phase; therefore it took a longer time to travel. It is important to avoid touching coated surface of TLC plate with your fingers because there are oils (organic compounds) on skin that will transfers…show more content…
When raising the pH of mobile phase buffer will cause the molecule become less protonated and hence less positively charged. The result is that the protein no longer can form an ionic interaction with the negatively charged solid support, which ultimately results in the molecule to elute from the column. Phenylalanine eluted fastest (pI=5.48) because it is lower than pH6. Leucine and Alanine was eluted next in pH6 because of their pI number 5.98 and 6.00, respectively. The next to elute out in pH11 buffer was Lysine. It has highest pI number (pI=9.74) and it will lose its charge at pH 11. Refer to figure 3, you can see phenylalanine and alanine showed up at pH 6 and pH 3, there was an error at pH 3 because the amino acid should not show up here based on their isoelectric point close to 6. The pH must be between the pI or higher in order for it to elute. The error maybe due the contamination while performing the experiment or can be not properly performed. Also, we can see that the lysine remained positively charge until it gets to pH 11 because the pI number is 9.74. On figure 3, it also showed phenylalanine at pH 11. This could be the amino acids were still in contact with the Dowex resin and Dowex was not
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