*3.2. NADES Extraction and Extracts Characterization*

A sample set of EVOOs (*n* = 26) was submitted to NADES extraction. Figure 2 reports the spectra of the NADES extracts (A), as well as the second derivatives (B) of the spectra. As a blank sample, a sunflower oil was submitted to NADES extraction in order to assess possible matrix effects due to components other than phenolic compounds, of which sunflower oil is void. The red dotted line in the panel of the second derivative spectra (B) represents the second derivative spectrum of the NADES extract obtained from the sample of sunflower oil (mean of three replicates). As can be seen, the curve appears flat and very near to zero. The second derivative spectra of the NADES extracts clearly reflect the spectral features of the mono- and *o-*diphenolic structures observed in the spectra of the standard compounds. In particular, negative peaks at 276–277 nm and 283 nm could be observed in all samples, as well as a positive peak at 292–294 nm. These wavelengths proved relevant in the analysis of EVOO phenolic compounds via NADES extraction [10,17].

**Figure 2.** Spectra (**A**), and second derivatives of spectra (**B**) of the NADES extracts of the EVOO samples (*n* = 26). The red dotted line in (**B**) reports the second derivative of the NADES extract of a sample of sunflower oil.
