What relationship does absorption have with concentration in absorption spectrophotometry?

In absorption spectrophotometry, the relationship between absorption and concentration is described by Beer-Lambert Law. This law states that absorbance (A) of a solution is directly proportional to the concentration (c) of the absorbing species in the solution, as well as the path length of the cuvette (l) and the molar absorptivity (ε) of the substance.

Mathematically, this is expressed as:

A = εlc

This means that as the concentration of the absorbing species increases, the absorbance increases linearly, assuming all other factors remain constant (i.e., the path length and molar absorptivity). Therefore, the correct relationship is that absorption is directly proportional to concentration. This understanding is critical in quantitative analysis, as it allows for the determination of concentration based on measured absorbance.

The other options do not reflect the principles established by Beer-Lambert Law and thus do not accurately describe the relationship between absorption and concentration in spectrophotometric measurements.