Numerical

Guanosine has a maximum absorbance of 275 nm. ϵ275=8400M−1cm−1${ϵ}_{275}=8400M^{-1}c{m}^{-1}$ and the path length is 1 cm. Using a spectrophotometer, you find the that A275=0.70$A_{275}=0.70$.  What is the concentration of guanosine?

SOLUTION

To solve this problem, you must use Beer's Law.
                                               $$A=ϵlc$$

0.70 = (8400 M-1 cm-1)(1 cm)(c$c$) 

Next, divide both side by [(8400 M-1 cm-1)(1 cm)]

                                                c$c$ = 8.33x10-5 mol/L