Figure . Evaluation of microenvironmental acidity through quantifying the miscibility of protein, sugar, and salt. C-detected 1 H T1ρ of BSA, trehalose, and buffer salt in spray-dried (A) and lyophilized (B) BSA formulations with potassium counterion at T0, and the corresponding scenarios of molecular mixing. Tre: trehalose; Pho: phosphate buffer; Suc: succinate buffer; Cit: citrate buffer; K: potassium. It is worth noting the phase-separated domain of succinic acid in the lyophilized formulation in (B).