Inspec on of the corresponding coefficients plot reveals that this drug-enriched layer at 1 min is approximately 10 µm wide, and in fact features two drug concentra on maxima with a small drug concentra on dip in between. Another, less intense, drug maximum is present at the x-axis posi on of approximately -26 µm. A er 2 min, phase separa on has intensified -the coefficients reveal sharper concentra on differences between the drug rich and polymer rich layers. Later me points feature more layers of phase separa on parallel to the original film-buffer interface. According to the coefficient plots, both the polymer and buffer coefficients consistently decrease together at the same posi ons where the drug coefficient increases. This can be a ributed to the water preferably associa ng with the hydrophilic polymer over the hydrophobic drug. This finding is in line with observa ons of Krummnow et al (2023) , who used spontaneous Raman line-mapping microscopy to quan ta vely image water-induced RTV and PVPVA phase separa on in 20% and 25% drug loaded ASDs over several days at 94% rela ve humidity.