Why do fingerprints absorb light? ... The presence of the finger prints will scatter the detector and absorb light causing higher absorbance and higher concentration results.

Do fingerprints affect absorbance?

Concentration will stay the same since the fingerprints will only deflect the light slightly and not enough to affect the absorbance measurements.

Why do fingerprints on a cuvette affect absorbance?

Fingerprints on a cuvette would affect absorbance and concentration calculation by the fact that fingerprints absorb and scatter light slightly, despite not be readily visible.