The generic method used in this application was developed to enable analysis of the ten most common counterions used in pharmaceuticals and dietary supplements within 20 minutes, using an isocratic carbonate-based eluent. A few coeluting anions were also injected to illustrate potential interferences.
Separation of pharmaceutical counterions on a Shodex IC SI-50 4E column (250×4 mm) using an eluent containing 4 mM Na₂CO₃ and 12 mM NaHCO₃ in water pumped at 0.8 mL/min at 24 °C from an EQAX-B1 eluent bottle equipped with an EQAX-TC1 trap cartridge for carbon dioxide removal. Background reduced to ~25 µS/cm by XAMS suppressor with ASUREX-A200 automatic regenerator. Eluent pumping and conductivity detection by Metrohm 761 Compact IC. Injection of 20 µL of acetate (1), mesylate (2), chloride (3), bromide (4), phosphate (5), nitrate (6), malate (7), sulfate (8), maleate (9), tartrate (10), oxalate (11), fumarate (12), at 5 or 20 mg/L (inorganic ions and organic acids, respectively) in water, giving signals up to 8 µS/cm.
Diduco is a leading provider of professional services in high performance liquid chromatography and manufacturer of the Xenoic® XAMS chemical suppressor and ASUREX automatic regenerator for ion chromatography.
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