Chapter 1, Problem 38P

To determine the concentration of a purified protein sample, a graduate student used spectrophotometery to measure the absorbance given in the table below:

$\begin{array}{cc}c\left(\mu \text{g/ml}\right)& a\\ 3.50& 0.342\\ 8.00& 0.578\end{array}$ The concentration-absorbance relations hip for this protein satisfies a linear equation $a=mc+a_i$, where c is the concentration of a purified protein, a is

The absorbance of the sample, in is the rate of change of absorbance a with respect to concentration c, and a₁ is the y -intercept.

(a) Find the equation of the line that describes the concentration absorbance relationship for this protein and determine the slope in of the linear relationship.

(b) Using the equation of the line from part (a). Find the concentration of the sample if this sample had absorption of 0.486.

(c) If the sample is diluted to a concentration of 0.00419 µg/ml, what would you expect the absorption to he? Would this value he accurate?

(d) Sketch the graph of absorbance a as a function of concentration c and clearly indicate both the slope in and the y -intercept.