Which fixative includes Formaldehyde, Calcium Chloride, DI water and is recommended for fixation and preservation of phospholipids in tissue?

• A. Calcium Formalin
• B. 10% Neutralized Formalin
• C. Formalin Alcohol
• D. Glutaraldehyde

Answer: (A)

Calcium formalin is used when you need to fix and preserve phospholipids in tissue. The formula combines formaldehyde in water with calcium chloride, so calcium ions are present during fixation. Those calcium ions interact with the phospholipid components of membranes, forming calcium-phospholipid complexes that help stabilize and retain phospholipids during processing. The formaldehyde still cross-links proteins, but the presence of calcium specifically supports lipid/membrane preservation in ways that plain aqueous formalin does not. That’s why this fixative is recommended for maintaining phospholipids. Other options lack the calcium to stabilize phospholipids, or use additives (like alcohol or different fixatives) that don’t optimize phospholipid preservation.