Characterisation of stationary phases in supercritical fluid chromatography with the solvation parameter model: V. Elaboration of a reduced set of test solutes for rapid evaluation

Characterisation of chromatographic systems with the solvation parameter model provides satisfactory information on the main non-ionic interactions developed in a chromatographic system. The procedure requires the analysis of a large number of compounds to warrant the relevance and the accuracy of the calculated models, and even if retention time is lower in supercritical fluid chromatography (SFC) than in HPLC (3–5 times lower), a decrease in the time required for that procedure would favour the use of this model in method development. Consequently, in order to establish a rapid testing procedure that would provide equivalent information, nine key solutes were carefully selected among the hundred we classically use. The separation factors calculated between these key solutes, taken two by two to establish new equations, allow the calculation of the model coefficients. The normal testing procedure is thus reduced from one or two days down to 2 h. Precision and accuracy of the models provided are assessed through back-calculation of the coefficients that served for the establishment of the procedure, then through calculation of the coefficients of 13 new SFC systems. The applicability of the rapid testing procedure in SFC is evidenced with three examples: the elaboration of a system map, by varying the modifier concentration in the mobile phase, and the comparison of six ODS phases bonded on the same silica base. The simplified procedure presented here does not pretend to characterize the chromatographic systems as precisely as the complete testing procedure does, but is only aimed at rapidly evaluating the chromatographic retention characteristics when operating parameters are varied.