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Spectrophotometer: Concentration and Standard Curve Essay

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Lab Report 4
Biology 103
Prof. Dr. Johnson
Spectrophotometer; the finding of protein concentration of an unknown sample of BSA, and by using the standard curve.

Abstract A spectrophotometer’s purpose is to use colors of the light spectrum to determine the concentration of light absorbing molecules in a solution. (p.59) In this particular lab, our mission was to determine the protein concentration and the standard curve of the unknown sample of BSA. This, by preparing five dilutions of the unknown solution of BSA together with other known concentrations, and then experimenting by observing how the concentrations were passed through the spectrophotometer. The outcome resolved in the absorption levels being decreased, and this
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The same solution of 0.5 ml BSA was then added from test tube 1 to the test tube 2 after being properly mixed, and from test tube 2 the solution was being added to test tube 3, and so forth all the way up to test tube 5, with the same exact procedure. From the last tube, we then disposed the 0.5 ml solution. After above procedures, we now labeled another test tube “blank”; 0.5 ml blank distilled water was purred into the tube with the serial dilution of 1:10. We also had a tube C labeled “unknown” with the same 0.5 ml of solution. And after adding 5ml of Coomassie Blue to each tube (1-5) and to the blank, the result of absorbance was read at 595 nm.

Result | Protein Concentration(µg/ml) | Absorbance(595 nm) | Tube 1 | 120 | .922 | Tube 2 | 60 | .557 | Tube 3 | 30 | .377 | Tube 4 | 15 | .180 | Tube 5 | 7.5 | .082 | Unknown: .759 |

The ending result of this experiment confirms that as five test tubes are lined up with the varying level of absorbance, different results in the level of absorbance will appear as well, this is visible in above table. Thus, this is due to the varying amount of water in the solution. The blank sample had a 0.30 in its level of absorbance.
Calculating serial dilutions and their concentrations
(Examples of test tube 1 and test tube 2for respective dilution and concentration)
Dilution or D = previous dilution (if any) ×the
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