Question

4, If a 0.1mM solution of a protein gave an absorbance of 1 absorbance unit. What is the concentration of a solution of this protein that after being diluted 1000 times gave an 280nm of 0.5 Absorbance units. absorbance at + ο.0001 OmM>A

Answer 1

Using the Beer's Lambert law

$A = \epsilon lc$

Using this equation

$\frac{A_1}{c_1} = \frac{A_2}{c_2}$

$A_1 = 1 \ absorbance \ unit, c_1 = 0.1 mM$

$A_1 = 0.5 \ absorbance \ unit, c_2 = (need \ to \ find)$

$c_2 = c_1(\frac{A_2}{A_1}) = \frac{0.1}{2} = 0.05 mM$

Since the solution is diluted to 1000 times, hence the original concentration of solution

$stock \ solution \ concentration = 1000c_2 = 0.05M \ or \ 50 m M$

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