Question

Photofrin (a photodynamic therapy agent for skin cancer treatment) has an extinction coefficient of 2000 Mcm at 630 nm. Suppose the absorbance of Photofrin, across the whole-skin-thickness of 2.30 mm, must be 0.1000 (no units) for it to provide adequate cancer-cell-killing capability when irradiated with 630 nm laser light. What concentration must it have in that skin layer?

Answer 1

A = EX cxl A e absor blence E= e ancentraten Extmelen coffinend l = length A = 0.1000 Exe &= 2000 my car l= 2.30 min = 0.23 Cm So - c = 2000 x 0.23 c = 0.000217 M C = 2.17 x 104 m