Plastic bags are used as containers for storage of donated blood. These bags are often made 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. BTHC is considered as a replacement for DEHP but studies show that it is less effective at stabilising blood cells. Using neutron reflectometry we aim to establish how BTHC interact with phospholipid monolayers and thereby understand the difference to DEHP. This comparison will help us connect biological functions to chemical effects. Insight into the stabilization will lead to greater understanding of how to preserve blood cells and increase the storage time of collected blood.