Application of green solvents for the separation of various compounds in reversed-phase liquid chromatography using stationary phases with different functionalities.

BACKGROUND: Currently, reversed phase liquid chromatography (RP LC) relies heavily on acetonitrile (ACN) and methanol (MeOH), presenting significant environmental and safety risks. This study evaluates green organic modifiers, specifically propylene carbonate (PC), dimethyl carbonate (DMC), and ethyl lactate (EL), as alternatives in RP LC using monodisperse stationary phases (Diphenyl, C18/AR, and RP18-Amide). The research was designed as a comparative study to determine the elution strength, efficiency and separation performance of three different mixtures.

RESULTS: By integrating chromatographic parameters with sustainability assessments, based on the TOPSIS algorithm combined with CHEMS-1 tool for greenness scoring of chemicals, study findings include: For the mixture of alkylbenzenes ranking, there is a clear order by mobile phase components, where the DMC/EtOH/water combination predominates. In the case of a mixture of isomers, the ranking is more stationary phase type dependent, whereas the ranking of a steroids mixture is more varied. It has been determined that the elution strength of the organic solvents used increases in the following order: MeOH < ACN ≈ PC/EtOH ≈ EtOH < EL/EtOH < DMC/EtOH. Comparative analysis revealed that PC/EtOH mixtures exhibited interaction mechanisms similar to those observed with ACN based on linear correlations with R2 > 0.99, which suggest a possibility for simple transition of existing methods, whereas the DMC/EtOH mixture provided a different selectivity profile, evidenced by a significant decrease in correlation (R2 reduced to even 0.87).

SIGNIFICANCE: This research proves that sustainable solvents can expand the separation capabilities of LC beyond traditional mobile phases.