Drierite

Drierite is a brand-name desiccant consisting primarily of anhydrous calcium sulfate (CaSO4) used to remove moisture from gases and liquids. It is widely used in laboratories and industry to keep equipment, solvents, and analytical samples dry.

Most Drierite products are supplied as beads or granules, sometimes with a color indicator that changes as the material hydrates (for example, cobalt salts that shift color when water is absorbed). When exposed to moisture, calcium sulfate converts to the dihydrate form, CaSO4·2H2O, and the drying capacity diminishes as saturation is reached.

Typical applications include drying inert gas streams before analytical instruments (such as gas chromatography and mass spectrometry), drying organic solvents, protecting moisture-sensitive reagents, and serving as a general desiccant in storage and handling areas. Drierite is valued for its relatively high moisture capacity, chemical inertia with many solvents, and ease of use in desiccation tubes, drying flasks, and sealed containers.

Handling and regeneration: Store in a tightly closed container to prevent moisture uptake. Replace saturated material or regenerate if appropriate for the grade—some formulations can be heated to drive off absorbed water, though many users prefer replacement for reliability. Drierite is generally non-reactive with common laboratory solvents under normal conditions and is considered a stable desiccant for routine moisture control.

See also: silica gel, activated alumina, desiccants.