A comparative study of two validated environmentally benign chromatographic methods for the simultaneous quantitation of a ternary mixture of empagliflozin, linagliptin, and linagliptin impurity
摘要
Currently, green chemistry’s primary criteria are the removal of dangerous compounds and the reduction of their harmful impacts on human health and the environment. Therefore, developing new analytical techniques necessitates taking these factors into consideration. Empagliflozin, linagliptin, and linagliptin impurity 5 ternary mixture were quantified in both pharmaceutical formulations and in their pure forms using two environmentally benign, simple, and reproducible chromatographic methods. The proposed thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) methods enable the concurrent determination of the two active drugs along with a related impurity of linagliptin in a single analysis, an aspect that remains limited in previously reported chromatographic methods. Separation was performed using the proposed TLC method. Silica gel F254 plates were employed as the stationary phase, while a mixture of methanol and acetone (8:2, V/V) was used as the mobile phase for band development. The bands were visualized under an ultraviolet (UV) lamp at 220 nm. The calculated retention factor (RF) values were 0.58 for empagliflozin, 0.25 for linagliptin, and 0.72 for linagliptin impurity 5. Calibration curves were constructed over the concentration ranges of 0.1–4, 0.1–2, and 0.1–1.2 µg/band for empagliflozin, linagliptin, and linagliptin impurity 5, respectively. Additionally, a complementary HPLC method was employed. Separation was achieved using a reversed-phase C18 column (250 mm × 4.6 mm, 5 µm particle size). Isocratic elution was performed using a mobile phase consisting of methanol and water (80:20, V/V). The flow rate was maintained at 1.2 mL/min, and detection was carried out at 220 nm. The mean retention times were 2.67 min for empagliflozin, 4.34 min for linagliptin, and 9.17 min for linagliptin impurity 5. The method exhibited linearity over the concentration ranges of 5–50, 2–30, and 1–15 µg mL−1 for the three components, respectively. Successful application to Empacyrl 10/5® tablets yielded results that were statistically comparable to those obtained from a previously cited procedure.