The calibration curves were freshly prepared on three different days to assess the linearity of the method. For this purpose, an 8-point calibration line was created by serially diluting the standards. The concentrations of these calibration points are presented in Table . Three types of calibration lines were prepared: 1) Neat solvents; 2) Spiking standards in HepG2 cells before performing the extraction as described in the sample preparation section; 3) Spiking standards in HepG2 cells after extraction. To determine the linear range, an unweighted linear regression model was employed. The calculation of various validation parameters was performed using cal-3 (low), cal-5 (medium), and cal-7(high) concentration levels.