Important note**: A UV-Visible Spectrophotometer measures molecules with conjugated systems and transition metals. Light passes through a monochromator to select a specific wavelength, which then interacts with the sample in a cuvette. The sample absorbs part of the radiation, and the remaining light reaches a detector, which processes the absorbance. The technique follows Beer's law, where absorbance is proportional to concentration. However, if the concentration is too high, the relationship becomes non-linear, and the solution is to reduce the concentration of standard solutions