Stability-indicating HPLC method for primaquine diphosphate: An application to niosomal formulation

A novel, rapid, and precise stability-indicating gradient reverse-phase high performance liquid chromatographic method for the quantitative determination of primaquine diphosphate and its impurities was developed and validated. Efficient chromatographic separation was achieved on an Inertsil ODS-3V column (150 mm × 4.6 mm, 5.0 μm) with mobile phase containing phosphate buffer (0.05 M KH2PO4, pH 4.5) in gradient combination with acetonitrile at a flow rate of 1 mL/min and the analyte was monitored using a photo-diode array detector at a wavelength of 254 nm. The forced-degradation of primaquine diphosphate was carried out by exposing it to acidic, basic, neutral, thermal, photolytic, and oxidative stress conditions. The peaks of the degradation products obtained were well resolved from that of primaquine diphosphate, indicating that the method developed was specific and stability-indicating. Further, the method was validated according to the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use guidelines, with respect to parameters such as specificity, precision, linearity, accuracy and robustness. The developed method could also be used for the quantification of primaquine diphosphate encapsulated in niosome formulation.