Question

You start with a solution that is 60 mg/ml of protein and perform a series of serial dilutions on it. Please fill in the table below with the appropriate concentrations at each dilution.

	Concentration (mg/ml)	Absorbance
1	60	.750
2		.340
3		.180
4		.08
5		.02

You have a mystery solution that has an absorbance of .250. Using the table, give an approximation or a range of concentrations that could be that or those of the mystery solution. Justify your answer.

Answer 1

Beer's Law Equation is given as (Absorbance = e*L*c), e is the molar extinction coefficient. L is the path length of the cell. c is the concentration of the solution.

Hence we can see that Absorbance is directly proportional to c

Hence for

2

Let x be concentration when absorbance is 0.34 so using the above law and taking the ratios

x/60=0.34/0.75 this gives x=60*(0.34/0.75)=27.2 mg/ml

3

Let x be concentration when absorbance is 0.18 so using the above law and taking the ratios

x/60=0.18/0.75 gives x=14.4 mg/ml

4

Let x be concentration when absorbance is 0.08 so using the above law and taking the ratios

x/60=0.08/0.75 gives x=6.4 mg/ml

5

Let x be concentration when absorbance is 0.08 so using the above law and taking the ratios

x/60=0.02/0.75 gives x=1.6 mg/ml

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