Scaling rule in SFC. II. A practical rule for isocratic systems

•Reporting further simplification of a recently reported SFC scaling process.•Applicability of maintaining the same average pressure evaluated.•Experimentally verified the range of applicability of average-pressure approach.•Demonstrated that this approach is applicable in lieu of average-density approach.

Scaling methods, either from analytical to analytical systems or from analytical to preparative systems and vice versa, are commonly performed in chromatography. For liquid chromatography there exist geometric rules for scaling, which provide guidelines to select column dimensions, particle sizes and flow rates. For SFC, on the other hand, there are no such rules or any well-understood principles behind scaling. In a recent report [1] this issue was addressed, proposing a rule of maintaining the same average density in the target system as it was in the original system. The problem with the criterion of maintaining average density, however, is the availability of density data. Not only one needs access and relevant experience of working with physical property data, in many cases density data may not be available at all. The current report demonstrates that a simpler approach, of matching average pressures, is equally applicable for acceptable scaling over most of the operating conditions used in SFC.