In 2010, the United States Pharmacopeia (USP) embarked on an initiative to modernize their monographs. As part of this effort, they introduced ion chromatography as a method for quantifying potassium. Ion chromatography stands out as a viable alternative because it allows the concurrent analysis of multiple cationic species.
Potassium plays crucial roles in nerve transmission, muscle contraction, fluid balance, and blood pressure regulation. Insufficient potassium levels (hypokalemia) can lead to symptoms such as cramps, constipation, or even heart failure. Mild to moderate hypokalemia is typically managed with potassium tablets or intravenous infusions.
To ensure the quality of pharmaceutical products and dietary supplements, it’s essential to accurately determine their potassium content and any potential impurities. As part of its modernization efforts [1], the USP has updated several monographs to include ion chromatography (IC) as a preferred method for analyzing potassium, alongside traditional techniques like atomic absorption spectroscopy (AAS) and flame photometry.
AAS and flame photometry require flammable gases and expensive equipment, whereas IC separates and quantifies ions based on their affinity to a stationary phase. This makes IC highly efficient and versatile as it can measure multiple analytes in one run without the need for manual matrix removal steps, even in complex samples with high concentrations.
The USP recommends using a separation column with L76 packaging, such as the Metrosep C 6 – 150/4.0, which is effective for separating cations at varying concentration levels [2]. All presented methods have been validated according to USP general chapters <1225> Validation of Compendial Procedures and <621> Chromatography.
To learn more about potassium analysis with ion chromatography as per the USP, refer to the following application notes:
- Potassium in Potassium Bicarbonate Effervescent Tablets for Oral Solution
- Potassium and Sodium Bicarbonates and Citric Acid Effervescent Tablets for Oral Solution
- Potassium in Potassium Bicarbonate and Potassium Chloride Effervescent Tablets for Oral Solution
For further insights into the application of ion chromatography across various USP test methods, visit Metrohm’s webpage on “Drug Monographs, Assays, and Impurity Evaluations Using Metrohm Ion Chromatography.”
[1] Santos, L. M.; Davani, B.; Anthony, C. M.; Clark, J. E. USP Monograph Modernization Initiative.
[2] Kardalas, E.; Paschou, S. A.; Anagnostis, P.; Muscogiuri, G.; Siasos, G.; Vryonidou, A. Hypokalemia: A Clinical Update. Endocrine Connections 2018, 7 (4), R135–R146.
[3] U.S. Pharmacopeia. USP-NF. §1225 Validation of Compendial Procedures.
[4] U.S. Pharmacopeia. USP-NF. §621 Chromatography.
