Protein adsorption at solid-liquid interfaces plays a key role in biomedical technologies such as biosensors or biomaterials for medical implants. Despite considerable progress in this field there are still widely differing and even contradicting opinions on the driving force of protein adsorption at an interface. Protein adsorption to non-biological substrates is even less studied in the presence of multivalent ions. In bulk, globular proteins tuned by multivalent ions how a rich phase behaviour featuring re-entrant condensation and liquid-liquid phase separation (LLPS). This proposal aims to relate the complex bulk phase behaviour to adsorption at an interface and furthermore the interface properties to the adsorption behaviour. Through the joint XRR and NR protein adsorption study, we aim to obtain sufficient contrast variation to fully an analyse our isotope-sensitive system.