[ubcdumbass]

... but that the absorptivity can be measured.
Can anybody give me a direction for where I can find this info? Confused as I believed molar absorptivity to be directly linked to the wavelength it was absorbing photons at, and therefore would need molar absorptivity. Thank you!

[mjc123]

Something for which the molecular weight is unknown or undefined, e.g. a polymeric sample whose MW has not been accurately determined. You can measure the absorbance of a sample, and get a specific absorbance (i.e. per unit mass), but not a molar absorptivity. (At least for the polymer; if its structure is well-defined, you may be able to get a molar absorptivity for the chromophoric group.)