HPLC Separation of Lithium, Sodium, Potassium and Ammonium Ions Using Zodiac HST- OG Column

Zodiac HST OG is a powerful Mixed mode columns, with an innovation chemistry in it. Whether you are separating polar, non-polar, neutral, ions, isomers or polar aromatic – Any kinds of compounds, It is possible to analyse them in one run

💡 Why this Order?

* The ions interact with the negative groups on the columns
* Retention increases as hydrated ion radius decreases and charge density increases.
* Li⁺ is heavily hydrated, so it interacts weakly with the stationary phase.
* K⁺, being larger and less hydrated, can get closer to the negatively charged sites and be retained longer.

So the elution order : Li⁺ → Na⁺ → NH₄⁺ → K⁺

🧪 Role of TFA ?

Without any counter ions the Cations will strongly bind to the column stationary phase making it very hard to elute creating broad peaks.

TFA acts as a counter-ion, pairing with positively charged analytes to reduce strong ionic interactions with the stationary phase. This results in sharper peaks, less tailing, and faster elution. Its low pH also stabilizes ionization, making it ideal for methods using ELSD detection.