“…In another investigation, Wang et al [ 30 ] reported R 2 values of 0.9992 and 0.9988 with HPLC and LC–MS, of the standard solution of ricinine with different standard concentrations (27.7, 13.8, 6.92, 3.46, 1.73, 0.87, 0.43, 0.22, 0.11, 0.05, and 0 µg mL −1 ) and (500, 250, 125, 62.5, 31.2, 15.6, 7.8, 3.9, 1.8 and 0 ng mL −1 ), respectively. Isenberg et al [ 31 ] determined the correlation of ricinine standard by HPLC, which showed a high linearity of R 2 = 0.996 with different ricinine standard concentrations (200, 20.0, 0.800, and 0 ng mL −1 ). In this research, a linearity of R 2 = 0.9618 was obtained with different ricinine standard concentrations (0, 6, 8, 16, 20 μg L −1 ); we proceeded to quantify the ricinine in the extracts.…”