Determination of sulfamate and sulfate in topiramate tablets according to USP monograph

Analysis of limit of sulfamate and sulfate in Topiramate tablets according to the specific tests defined in USP 41 (monograph 2018:4145). Ion chromatography separation on a USP class L47 column (Hamilton PRP-X100, 150×4.6 mm, 5 µm) using an eluent containing 97.5% of aqueous 0.8 g/L (5.8 mM) p-hydroxybenzoic acid at pH 9.4 with 2.5% methanol, pumped at 1.5 mL/min at 30 °C. Background reduced to ~123 µS/cm by XAMS suppressor with ASUREX-A100 automatic regenerator. A Waters ACQUITY Arc system with modules QSM-R and FTN-R were used together with a Waters 432 conductivity detector. Injection of 70 µL of ground tablet powder (1 g) that had been diluted in mobile phase (50 mL), sonicated and filtered through 0.45 µm PES (solid line), or of a standard with 15 ppm sulfamate and 15 ppm sulfate in eluent (broken line, offset by 50 µS/cm).