Retention of TFA on Atlantis and Zodiac HST N Column

Trifluoroacetic acid (TFA), a strong carboxylic acid with a pKa of approximately 0.3, is commonly used in chemical synthesis as a reagent and as a counter-ion for basic compounds and pharmaceuticals. Due to its high polarity and low UV absorbance, quantitation of TFA in various formulations can be challenging. The Zodiac HST N column offers a robust HPLC method for accurate determination of TFA. Retention is achieved through ion-exchange interactions on this mixed-mode HILIC column.

Compared to conventional reversed-phase columns, such as the Atlantis T3 (Waters), Zodiac HST N delivers superior peak shape, improved retention, and enhanced loadability. Optimization of acetonitrile content, buffer pH, and buffer concentration ensures excellent peak symmetry. Detection is typically performed at low UV wavelengths (200 nm). Alternatively, TFA can be effectively quantified using evaporative light scattering detection (ELSD) when using ammonium formate in the mobile phase, which forms a non-volatile salt with ammonia, enhancing detection sensitivity.