HPLC Retention of Sulfuric Acid on Zodiac HST N Column

Sulfuric acid is a strong mineral acid with a pKa below zero. It is a clear, colorless, and highly corrosive viscous liquid commonly used in chemical and pharmaceutical manufacturing as a reagent, drying agent, and counter-ion for basic compounds. Due to the absence of UV chromophores, sulfuric acid cannot be detected by UV, but it can be quantified using ELSD or conductivity detection.

A fast and robust HPLC method was developed on the Zodiac HST N column using a mixed-mode ion-exchange approach. Retention of sulfuric acid is achieved primarily through anion-exchange interactions. The behavior of the Zodiac HST N stationary phase is influenced by the acetonitrile content in the mobile phase, allowing flexible method optimization.

The high ion-exchange capacity of the Zodiac HST N column, combined with the sensitivity of ELSD detection, enables accurate quantitation of sulfuric acid across a broad concentration range, even in the presence of co-formulated basic compounds.