Plastic bags are used as containers for storage of donated blood. These bags are typically made out of PVC plasticized with dialkylphthalates (e.g. DEHP), which migrates into the blood and has been found to stabilize the membranes of red blood cells and thereby increases the shelf life of the stored blood. DEHP is inherently toxic and a non-toxic alternative is desired that does not sacrifice shelf life of stored blood. Using neutron reflectometry we aim to establish how different plasticizers interact with phospholipid monolayers and thereby connect biological functions to chemical effects. Insight into the stabilization will lead to greater understanding of how to stabilize blood cells and increase the storage time of collected blood..