Lab Report: Relationship between Concentration and Absorbance

involves measuring the absorbance of several concentrations of the pure substance or the "standard" substance

determine relationship between concentration and absorbance

compared results from unknowns
How to use Linear Regression for
Generating a Standard Curve?
© 2010 by M. Olaveson UTSC
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BIO A01F-Fall 2010 - ASSIGNMENT # 2 - Preparing a Standard Curve using Excel 2007

Assignment # 2
Analysis of Data from Lab 2-Exercise 2
Table 2.6. Protein in Test Tubes prepared for Standard Curve.
1. Follow instructions in Lab Manual and complete Table 2.6
© 2010 by M. Olaveson UTSC
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BIO A01F-Fall 2010 - ASSIGNMENT # 2 - Preparing a Standard Curve using Excel 2007

Assignment # 2:
Table 2.7. Absorbance (at 550 nm) as a function of protein concentration.
2. Complete Table 2.7
© 2010 by M. Olaveson UTSC
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BIO A01F-Fall 2010 - ASSIGNMENT # 2 - Preparing a Standard Curve using Excel 2007

5. After plotting XY Scatter Plot – perform a Linear Regression Analysis to generate a “line of best fit’ by using the “Trendline” option Determine the Equation for the Line and the Correlation Coefficient (R2 Value) by clicking the options in the “Trendline” menu: - choose “intercept = 0” - choose “show equation” choose show “R2 value”
Use Equation to determine the protein concentration in the Unknown Sample (make sure to indicate Unknown #)

Complete Assignment # 2 according to Instructions on Blackboard under “Assignments – Assignment # 2” and submit to your TA at beginning of Lab 3
© 2010 by M. Olaveson UTSC
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BIO A01F-Fall 2010 - ASSIGNMENT # 2 - Preparing a Standard Curve using Excel 2007
Assignment # 2:
From Table 2.7 – use the Protein Concentration and corresponding Absorbance (at 550 nm) to plot an XY Scatter Plot (using Excel / Star Office / Graphing Program)

HINT: graphing options are found in the Chart Function in Excel (use Chart Wizard)

Follow instructions in: Appendix 2 (p. 196-198) in Knisely, K. 2005. A Student Handbook for Writing in Biology (2nd Edition). Sinauer Assoc. Sunderland, Mass. Appendix 2 (p. 221-226) in Knisely, K. 2009. A Student Handbook for Writing in Biology (3rd Edition). Sinauer Assoc. Sunderland, Mass.
© 2010 by M. Olaveson UTSC
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BIO A01F-Fall 2010 - ASSIGNMENT # 2 - Preparing a Standard Curve using Excel 2007
Assignment # 2:

TUBE | WATER ADDITION | CASEIN ADDITION | AMOUNT OF CASEIN in 2 ml | CASEIN CONCENTRATION | | | | SOLUTION | (mg CASEIN / 1 ml solution) | | | | (mg CASEIN) | | 1 | 2.0 ml | none | 0 | 0 | 2 | 1.5 ml | 0.5 ml | 5 | 2.5 | 3 | 1.0 ml | 1.0 ml | 10 | 5 | 4 | 0.5 ml | 1.5 ml | 15 | 7.5 | 5 | none | 2.0 ml | 20 | 10 | 6 | none | 2.0 ml of protein sample of unknown concentration |

TUBE | C1 | V1 | V2 | C2 | ABSORBANCE | | PROTEIN CONC. | Volume (ml) | Volume (ml) | PROTEIN CONC. | (at 550 nm) | | (mg/ml) | before adding Biuret Solution | after | (mg/ml) | | | before adding Biuret Solution | | adding Biuret Solution | after adding Biuret Solution | | | (from Table 2.6) | | | | | Tube 1 (blank) | 0 | 2 | 10 | 0 | 0 | Tube 2 | 2.5 | 2 | 10 | 0.5 | 0.226 | Tube 3 | 5 | 2 | 10 | 1 | 0.334 | Tube 4 | 7.5 | 2 | 10 | 1.5 | 0.496 | Tube 5 | 10 | 2 | 10 | 2 | 0.558 | Tube 6 | | 2 | 10 | | 0.189 | Unknown Sample # _______ | | | | | |