HPLC Seperation of Alginic Acid in Heartburn Tablets

Alginic acid is a linear copolymer composed of homopolymeric blocks of (1-4)-linked β-D-mannuronate (M) and its C-5 epimer, α-L-guluronate (G), covalently bonded in various sequences. These sequences can include G-blocks (consecutive G residues), M-blocks (consecutive M residues), alternating MG-blocks, or randomly arranged blocks. The molecular weight of alginic acid ranges from 10,000 to 600,000, making its analysis particularly challenging due to the broad molecular weight distribution.

Using the Zodiac HST C mixed-mode cation-exchange column, alginic acid can be analyzed under ion-exclusion and size-exclusion modes. It elutes as a single, well-shaped peak before the void volume, indicating effective separation and peak symmetry. This method is suitable for the quantitation of alginic acid in a variety of formulations and is compatible with low-wavelength UV or ELSD detection.