Amino Acids Lab Report

Processing Raw Data

Calculations

The equationsRf(A) =LAL0 and Rf(A) =LBL0 were used to calculate the Rf values, A standing for the distance the green pigment traveled and B standing for the distance the yellow pigment traveled. For trial 1 of Nandina domestica, the L0 = 3.50 cm and the LA = 0.70 cm. Therefore,

Rf(A) =LAL0= 0.70 cm3.50 cm= 0.200. A Rf value of 0.200 corresponds with the amino acid arginine. This was repeated for each trial of each leaf and the amino acids were identified.

Retention factors and closest corresponding amino acids

Rf (A)

Nandina domestica

Amino

acid

Buxus sempervirens

Amino

acid

Stachys byzantina

Amino acid

Trial 1

0.200

arginine

0

none

0

none

Trial 2

0.345

threonine

0.257

glycine

0

none

Trial 3

0.186

arginine

The Rf values of the other trials were not affected enough to change their corresponding amino acids. In order for this to be reduced, a more precise measuring device should be used. Systematic error seems to have played a large part in some of the outlying data points. For example, trial 1 of Buxus sempervirens and trials 2 and 3 of Stachys byzantina didn’t separate into any pigments. This could be due to the texture or the toughness of the leaf. The Buxus sempervirens leaves are very tough and were difficult to rub onto the chromatography paper, possibly causing there to be less available to separate. The Stachys byzantina leaves are very soft and delicate, but also dry. It was difficult to get much liquid to transfer to the paper, which makes it less likely to separate. It seems that the systematic error had a greater effect on the data than the random error. This occurred due to insufficient experience with this method of chromatography. If more trials were conducted, then this error could have been decreased. In addition, the amount of chromatography solvent in each test tube was not always equal, as the pipet was not consistent. Therefore, the amount of solvent traveling up the chromatography may not have been equal in each trial. Despite the errors, the amino acid that was most abundant was arginine, which agrees with what Kumar et al. (2016)

Since all three trials for each leaf were done at the same time, there was no way to learn from the mistakes. With more trials, the problem with the transferring of pigment to the paper could have been analyzed and solved. This would have led to more accurate Rf values and subsequently, more accurate amino acids. Each group of trials should have taken about 10-15 minutes but after a few trials, the papers may have been removed from the test tubes early. This could have led to incorrect Rf values by altering the ratio of the distance that the solvent traveled and the distance the pigments travelled. The chromatography solvent may have created a few issues as well. In a first attempt at the experiment, none of the leaf pigments separated from the origin. The solvent that was used was from a bottle of reused chromatography solvent. Once the solvent was used straight from its original bottle, the pigments began to separate. In addition, the solvent was not always at equal levels as it was difficult to precisely measure with the pipet. The measuring tool used for this experiment was not the most precise instrument that could have been used. This may have led to some miscalculations, but as seen before, they were not