In a common protein analysis, a dye binds to the protein and the color of the dy
ID: 475521 • Letter: I
Question
In a common protein analysis, a dye binds to the protein and the color of the dye changes from brown to blue. The intensity of the blue color is proportional to the amount of protein present. After subtracting the blank absorbance (0.423) from the remaining absorbances, use the method of least squares to determine the equation of the best straight line through these five points (n = 5) use the standard deviation of the slope and the intercept to express the equation in the form y = [m(plusminus 5_m)] x + [b(plusminus 5_b)]. Show your calculations and check your answer using the linest function on Excel. Attach a graph showing the experimental data and the calculated straight line (use Excel) An unknown (single sample) gave an observed absorbance of 0.973 (blank not subtracted). Calculate the number of micrograms of protein in the unknown, and calculate the uncertainty.Explanation / Answer
After subtracting the blank absorbance the data is plotted and is shown below
data points
the equation of best fit is Absorbance = 0.023* protein mass +0.251
given actual absorbance =0.973-0.423= 0.55
hence 0.55 = 0.023* protein mass +0.251
Protein mass = (0.55-0.251)/0.023= 13 ug