*7.1. Spectrophotometric Methods*

According to the Royal Spanish Academy, spectrophotometry is a scientific method widely used to determine how much light a chemical compound absorbs and is based on the Beer-Lambert law. The Beer-lambert law is a combination of the other four laws (Bouguer, Bunsen, Roscoe, and Beer) that enabled it to be enunciated. According to Hardesty and Attili [37], "*the intensity of a monochromatic light beam incident perpendicular on a sample decreases exponentially with sample concentration*". This law states that:

$$A = K \* \mathbb{C} \tag{1}$$

where, *A* = Sample absorbance; *K*= Constant of wavelength, which is fixed according to the nature of the substance analyzed and the material of the cell used; and *C* = Sample concentration.

Then, if we look at this equation closely, we will see a similarity with the equation of the line, which, since it lacks an interjection point with the coordinates (n), we can infer that it would pass through the origin of the coordinates (standard); where "*K*" is the slope of the line [38].

There are several modifications and adaptations to this process, and we will discuss some of the more widely used spectrophotometric methods for the analysis of fungal pigments below.
