Donated blood is typically stored in bags made of PVC plasticized with DEHP. DEHP migrates into the blood and the amount in the blood cells can be 5 to 10% of the phospholipid content. This stabilizes the membranes of red blood cells and increases the shelf life of stored blood. DEHP is toxic and a non-toxic alternative is desired. We now plan to extend previous studies on a two-component system of the lipid, DMPC with DEHP by adding cholesterol. We will investigate the role of DEHP in a system with more relevant composition where it causes different behaviour. Monolayers will be investigated at an air-water interface using specular reflectivity. Insights into stabilization will lead to greater understanding of how to preserve blood cells and increase the storage life of donated blood.