As we discussed in lecture, UV$-$Vis spectroscopy may be employed to determine the

purity of a DNA or protein sample. DNA and protein are distinguished by virtue of their

different UV absorption properties, DNA having an absorption maximum at $260nm$ and

protein at $280nm.$

Consider the following example. The optical density of standard solutions of DNA

M$)$ and protein $({10}^{-6}M)$ are measured at $260$ and $280nm$ in a standard $1cm$ path$-$length

cuvette with the results shown below.

a$)$ Calculate the extinction coefficients of both the DNA and the protein at both $260$ and

$280nm.$

b$)$ Calculate the absorption that you would measure in a $1$:$1$ mixture of these standard

solutions at both $260nm$ and $280nm.$