Any potential of new biotechnological processes would be assuredly canceled in the absence of efficient separation strategies. This work comprehensively addresses the solutes partitioning behavior in biocompatible carbohydrate-polymer aqueous biphasic systems (ABSs) to explore the separation performance of these systems. The complete liquid–liquid phase diagrams were determined for sucrose/glucose-polypropylene glycol (PPG) ABSs at 25 °C and atmospheric pressure. Then, the partitioning pattern of four biomolecules, including caffeine, codeine, vanillin, and curcumin, was investigated in the carbohydrate-PPG ABSs. The obtained results show that caffeine, vanillin, and curcumin are mostly electrically neutral in the medium of the studied ABSs and preferentially concentrate in the more hydrophobic PPG-rich phase with the maximum partition coefficients (K) of 2.05, 19.75, and 246.37, respectively. However, codeine, being present mainly in the cationic form in the ABSs investigated, has a high tendency for the more hydrophilic carbohydrate-rich phase with the highest K−1 = 16.85. The magnitude of log K values for all the target biomolecules linearly increases by decreasing the water content ratio of the coexisting phases. The maximum value of the caffeine/codeine selectivity index was estimated to be 34.5 at optimum conditions. The best value of K did not necessarily correspond to the maximum recovery percentage (R) because the volume ratio of phases is another factor that can affect the R values. The curcumin partitioning behavior in carbohydrate-propanol ABSs was also investigated to provide a competitive platform. The gathered results indicate that although both carbohydrate-PPG and carbohydrate-propanol ABSs provide satisfactory partitioning performance for vanillin and curcumin, carbohydrate-PPG ABSs own a higher selectivity index for the alkaloids studied.
