Spectrophotometer: Concentration and Standard Curve

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  • Topic: Dilution, Concentration, Serum albumin
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  • Published : November 29, 2011
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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.

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 gave us an opportunity to plot the measured absorption levels and protein concentrations.

Absorption spectroscopy is a common method for finding the concentration of proteins or protein complexes in a solution. Proteins absorb light at specific wavelengths and can be defined by the equation A = log (I0/IT). These equations states that an absorbance at a specific wavelength, A, is equal to the log of the ratio of incident light intensity, I0, to transmitted light intensity. (p. 59-60) In this study, our purpose is, again, to develop a standard curve for Bovine Serum Albumin, and this is done by preparing at least five dilutions. According to most research findings, scientists suggest that to determine the standard curve or concentration of an unknown sample of BSA using a quantitative spectrophotometer, the standard is diluted to a range from 0.01µg/ml to 10µg/ml.

Material and method
This particular experiment includes; spectrophotometer, 240µg/ml of Bovine Serum Albumin (BSA), 5 test tubes, Coomassie Blue, beaker, pipette/micropipettes, and distilled water which is the dependent variable. The starting point; 0.5 ml of distilled water was to be added to each labeled test tube (1-5), so as the...
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