Fig. 4

UV-Vis spectra of Cannabis sativa extracts. a The spectrum of the SB3 extract at 0.6; 0.8; 1.25; 1.7 mg/mL in 100 mM phosphate pH 7.4 is shown as an example. The inset shows the linear regression of absorbance at 257 nm (●) and 298 nm (♦) against the concentration of extract. b Correlation between the levels of THC-A determined by ¹H-RMN and the extinction coefficients (ε) at 257 nm (○) and 298 nm (●) determined from the slope of plots as the one represented in the inset of (a)