Question

An opaque sample has infinite absorbance. However, the maximum obtainable absorbance reading from a given a UV-Vis spectrophotometer is limited by “stray light” inside the instrument—light that somehow reaches the detector without actually traveling through the sample. What is the maximum reading if this stray light is 0.1% of the light transmitted through a blank sample? What stray light percentage would be required for a maximum absorbance reading of 5?

Answer 1

What is the maximum reading if this stray light is 0.1% of the light transmitted through a blank sample:

Absorbance (A) = - log(%transmittance / 100)

Here transmittance = 0.1%

A= -log (0.1/100)

Absorbance (A) =3.0

What stray light percentage would be required for a maximum absorbance reading of 5?

Here A = 5.0

Absorbance (A) = - log(%transmittance / 100)
5.0 = - log(%transmittance / 100)

10^-5 = %transmittance / 100

1*10^-5= %transmittance / 100

%transmittance = 1*10^-3.