An eco-friendly HPLC method for simultaneous analysis of sildenafil and sodium benzoate in pulmonary arterial hypertension suspension dosage monitoring

The purpose of this research is to develop a fast, environmentally friendly, precise, sensitive, and specific high-performance liquid chromatography (HPLC) method for the simultaneous determination of sildenafil and sodium benzoate in bulk raw materials and in the legally marketed reference drug (Revatio powder for oral suspension). The optimized mobile phase flow rate was 1 mL/min, with the mobile phase consisting of 600 mL of 0.2% v:v phosphoric acid aqueous solution and 400 mL of ethyl alcohol. The range of linearity used for sildenafil and sodium benzoate was 3.5-280 µg/mL (sildenafil) and 0.35-28 µg/mL (sodium benzoate), respectively. The wavelength used to analyze the samples was 230 nm; the sample size was 10 µL; and the analysis time was less than 4.5 min. The ultimate scores are as follows: 0.63 for the Analytical Greenness Metric for Sample Preparation (AGREEprep), 72.22 for the Analytical Green Star Area (AGSA), 80 for the Blue Applicability Grade Index (BAGI), 72 for the Click Analytical Chemistry Index (CACI), 88 for the Carbon Footprint Reduction Index (CaFRI), 89 for the Analytical Ecoscale (AES), and 78 for the Modified Green Analytical Procedure Index (MoGAPI), and an (A) letter score of 75.3% indicates the whiteness level using the Multi-color Assessment (MA) Tool, and all imply the high sustainability, greenness, whiteness, and economic wisdom of the current method. All validation characteristics have followed the International Council for Harmonisation (ICH) and United States Food and Drug Administration (US FDA) validation guidelines. Compared to complicated systems such as Ultra-performance Liquid Chromatography-tandem Mass Spectrophotometry (UPLC-MS), it has benefits including shorter retention times, less reagent usage, simultaneous analysis, and cheaper prices.