Quantifcation of Residual Organic Solvents in Siponimod Using Headspace Capillary Gas Chromatography

Objective To develop a headspace capillary gas chromatography (HS-GC) method for the determination of residual solvents in Siponimod active pharmaceutical ingredient (API), including methanol, ethanol, acetone, isopropanol, acetonitrile, methylene chloride, ethyl acetate,tetrahydrofuran, n-heptane, toluene, N,N-dimethylformamide, and dimethyl sulfoxide. Methods The analysis was performed using HS-GC with an Agilent DB-624 capillary column (60 m × 0.32 mm, 1.80 µm). The temperature program was set as follows: initial temperature of 45°C held for 17 minutes, then increased to 240°C at a rate of 15°C per minute and held for 10 minutes. Helium was used as the carrier gas at a flow rate of 1.0 mL/min. The injector temperature was set at 210°C, and the FID detector temperature was 260°C. The headspace equilibrium temperature was 105°C, and the equilibrium time was 35 minutes. Results All 12 residual solvents were completely separated. Each solvent showed a good linear relationship between concentration and peak area within the tested range, with correlation coefficients (r) no less than 0.999. The average recovery rates ranged from 95.3% to 100.9%, and the relative standard deviations (RSD) were between 0.8% and 2.7% (n=9). Conclusion This validated analytical approach demonstrates exceptional accuracy, reproducibility, and high sensitivity, enabling robust quantification of 12 residual solvents in siponimod API through a harmonized protocol compliant with ICH Q3C and pharmacopeial standards. Its optimized efficiency and scalability render it a pivotal solution for pharmaceutical quality assurance systems.