Table 1 Experiment 1 Standard Curve Tube Final Protein Concentration L of BSA protein stock 0 5 mg mL Bradford Reagent 8 7 6 5 4 3 2 1 50 g ml 25 g ml 15 g ml 10 g ml 7 5 g ml 5 0 g ml 2 5 g ml 0 g ml 100 L 50 L 30 L 20 L 15 L 10 L 5 L 0 L 900 L 900 L 900 L 900 L 900 L 900 L 900 L 900 L 0 15M NaCl for 1 0 mL final volume 0 L 0 mL 50 L 0 05 mL 70 L 0 07 mL 80 L 0 08 mL 85 L 0 085 mL 90 L 0 090 mL 95 L 0 095 mL 100 L 0 1 mL Figure 1 Table 1 Calculations Table 2 Experiment 1 Standard Curve Final Concentration Absorbance 595 nm 50 g ml 25 g ml 15 g ml 10 g ml 7 5 g ml 5 0 g ml 2 5 g ml 0 g ml 0 37 0 19 0 15 0 14 0 11 0 06 0 02 0 00 Figure 2 Table 2 Graph All 8 data points Figure 3 Table 2 Corrected Curve Graph 2 Highest Concentrations Removed Table 3 Part B Protein Concentration in Milk My Milk Type 2 The Dilution of milk I used was 1 10 Tube Unknown Volume Bradford Reagent 1 2 3 4 5 L 900 L 95 L 0 095 mL 0 23 10 L 900 L 90 L 0 090 mL 0 41 20 L 900 L 80 L 0 080 mL 0 54 40 L 900 L 60 L 0 060 mL 0 69 A595nm 0 15M NaCl for 1 0 mL final Concentration Measured by Spec g mL Concentration of Unknown Volume g mL 20 21 corrected curve or 28 59 uncorrected 36 42 corrected curve or 54 30 uncorrected 48 14 corrected curve or 72 87 uncorrected 61 65 corrected curve or 94 30 uncorrected 40420 corrected curve or 57180 uncorrected 36420 corrected curve or 54300 uncorrected 24070 corrected curve or 36435 uncorrected 15412 5 corrected curve or 23575 uncorrected Figure 4 Table 3 Calculations using both corrected and uncorrected curve Questions a What was your final R2 value What does this tell us about the precision of your measurements On the original graph R2 0 9523 On the corrected graph R2 0 9154 This tells me that my measurements are precise because they are close to 1 The closer to 1 R2 is the better it fits the data R2 1 is a perfect fit b Look at the final two values of your standard curve on the scatter plot do they correlate strongly with the rest of your data Why or why not No they do not correlate strongly with the rest of my data because they are very small values so they do not touch the line of best fit they fall under the treadline c What happens to your R2 values if you exclude the last two values in the curve does that change the concentrations of your unknown If so which should you use to calculate the unknown concentration in milk Yes excluding the last two values in my curve changes the concentrations of my unknown by changing the entire equation as well as the R2 value Due to this I should use the original equation when calculating the unknown concentration in milk because the R2 is greater closer to 1 and therefore a better fit Under my calculations you will see there s a big difference depending on the equation used d What is the concentration of the milk solutions in the cuvette Show your work in what you hand in it s worth points Either construct what you did digitally 2 2 4 1 or take a photo of your work and insert it into the document Figure 5 Column 6 Calculations e What is the concentration of protein in your milk Did you use all data in calculating the unknown concentration If you excluded some data provide a justification Remember you must account for dilution Show your work Figure 6 Column 7 Calculations f How does your determined concentration compare to the concentration of protein listed on the milk carton 2 milk has 33 3 g uL of protein Compared to the values I got in Table 3 column 7 this value is a lot smaller Tube 1 40420 g mL corrected curve or 57180 g mL uncorrected Tube 2 36420 g mL corrected curve or 54300 g mL uncorrected Tube 3 24070 g mL corrected curve or 36435 g mL uncorrected Tube 4 15412 5 g mL corrected curve or 23575 g mL uncorrected
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