Dilute BSA Standards

1. Label 9 tubes 1-9
2. Combine the components of the table below to generate appropriate concentration of solutions

Solution (ml)	BSA Standard Dilution						Unknown		Blank
	1 0.1mg/ml	2 0.2mg/ml	3  0.4mg/ml	4 0.6mg/ml	5  0.8mg/ml	6 1.0mg/ml	7	8	9 0.0mg/ml
BSA	0.1	0.2	0.4	0.6	0.8	1	–	–	–
H2O or Buffer	0.9	0.8	0.6	0.4	0.2	–	–	–	1
Sample	–	–	–	–	–	–	1	1	–
Biuret	4	4	4	4	4	4	4	4	4

3. Place tube 9 (blank) into a cuvette and measure absorbance (A) in the spectrophotometer at 540 nm
4. Calibrate the spectrophotometer to read 0 at A_540nm
5. Sequentially read each sample at A_540nm and record values in table below

Test Tube	BSA (mg/ml)	Absorbance 540 nm
1	0.1
2	0.2
3	0.4
4	0.6
5	0.8
6	1.0
Use the Plot to determine the concentrations for the values below. Do not add the points below to your plot.
7	—
8	—

6. Plot each BSA dilution in a spreadsheet program like Excel as a scatterplot
7. Generate best-fit line for these standards with the equation of the line
8. Use the equation of the line to estimate the concentration of the unknown sample.

 

Curve Fitting

Run the simulation below to understand how you can use the standard dilution series to estimate your sample concentrations.

Scatterplot Tutorial

Use the tutorial below and watch at 1.25X to plot your own data.

Tags: quantitative reasoning