Pyrogenic Properties of Ultrapure Water

Characteristics of Pyrogen Properties in Ultrapure Water

I. Water Solubility: Pyrogens are soluble in water, and their concentrates often have an opalescent appearance.

II. Small Size: The size, morphology, and chemical composition of pyrogens vary depending on the bacterial species. Bacterial endotoxins are much smaller than bacteria themselves, ranging from only 1-50 nm. Lipid A is even smaller, with a relative molecular mass of only a few thousand, making them difficult to remove using conventional filtration methods.

Due to their small size and light weight, they can sometimes even escape into the distilled water as water vapor during distillation.

III. High Thermal Stability: Bacterial endotoxins are highly heat-resistant. They show little change below 100°C, and heating at 120°C for 4 hours only destroys 98% of their activity. Complete inactivation requires heating at 180°C for 2 hours or more.

Such removal methods are quite difficult to implement.

IV. High Chemical Stability: Generally, chemicals do not affect the activity of bacterial endotoxins. Only strong acids, strong bases, or strong oxidizing agents (such as potassium permanganate or hydrogen peroxide) can destroy bacterial endotoxins.