3.2.2. Determination of the Molar Extinction Coefficient of the Compounds

Each compound’s stock solutions were prepared to determine the compounds’ molar extinction coefficient (ε). Solutions for the spectroscopic measurements were prepared by immediately dissolving accurately weighed amounts of compounds in the appropriate solvent volume before running the spectra. The absorption spectra were recorded on a Cary 100 Bio UV/visible spectrophotometer (Walnut Creek, CA, USA) using a rectangular quartz cuvette with a path length of 1 cm, and an absorbance scan was performed in the wavelength range of 190 to 600 nm. To determine the ε of each compound, we worked with a group of solutions with concentrations of 5, 10, 20, 30, and 40 mg/mL, a range in which the changes in absorbance was linear (r = 0.9989). This allowed obtaining the absorbance results at a concentration of 1 mg/mL and obtaining the coefficients (Table 5).

UV molar extinction coefficients of compounds in aqueous phase. Percentage relative error < 5%.