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Why does greater analyte concentration usually produce greater absorption of radiation?

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Greater analyte concentration results in increased absorption of radiation because the absorptive capacity of a dissolved substance is directly proportional to the number of absorbing particles present in the solution.1

This relationship is defined by the Beer-Lambert law, which is expressed by the equation:

$A = ϵ l c$

In this formula:
* $A$ is the absorbance.
* $ϵ$ is the molar extinction coefficient, which is specific to the chemical nature of the substance and the wavelength of the light used.
* $l$ represents the path length the light travels through the medium.
* $c$ is the concentration of the analyte.1

As the concentration ( $c$ ) increases, there are more molecules available to interact with the incident radiant energy, thereby increasing the total amount of radiation absorbed as it passes through the medium.21