Chemometric evaluation of the combined e

The need to determine the actual operational conditions, instead of merely using the set operational conditions, was investigated for packed supercritical fluid chromatography (SFC) by design of experiments (DoE) using pharmaceutical basics as models. The actual values of temperature, pressure, and methanol levels were recorded and calculated from external sensors, while the responses in the DoE were the retention factors and selectivity. A Kromasil CelluCoat column was used as the stationary phase, carbon dioxide containing varying methanol contents as the mobile phase, and the six racemates of alprenolol, atenolol, propanolol, propranolol, clenbuterol, and mianserin were selected as model solutes. For the retention modeling, the most important term was the methanol fraction followed by the temperature and pressure trends. Significant differences (p < 0.05) between most of the coefficients in the retention models were observed when operational methods set and actual conditions were compared. The selectivity was much less affected by operational changes, and therefore were not severely affected by the difference between actual and set operational conditions. The study demonstrates that the actual conditions should always be preferred.