title: Chemometric evaluation of the combined effect of temperature, pressure, and co-solvent fractions on the chiral separation of basic pharmaceuticals using actual vs set operational conditions.
abstract: The need to determine the actual operational conditions, instead of merely using the set operational conditions, was investigated for in packed supercritical fluid chromatography (SFC) by design of experiments (DoE) using a most important type of compounds, 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, metoprolol, 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. Significant differences (p<0.05) between most of the coefficients in the retention models were observed when comparing models from set and actual conditions. The selectivity was much less affected by operational changes, and therefore was not severely affected by difference between set and actual conditions. The temperature differences were usually small, maximum ±1.4°C, whereas the pressure differences were larger, typically approximately +10.5bar. The set and actual fractions of methanol also differed, usually by ±0.4 percentage points. A cautious conclusion is that the primary reason for the discrepancy between the models is a mismatch between the set and actual methanol fractions. This mismatch is more serious in retention models at low methanol fractions. The study demonstrates that the actual conditions should almost always be preferred.
authors.affiliation: Department of Engineering and Chemical Science, Karlstad University, SE-651 88 Karlstad, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Forss
authors.affiliation: Department of Engineering and Chemical Science, Karlstad University, SE-651 88 Karlstad, Sweden.
authors.forename: Dan
authors.initials: D
authors.lastname: Haupt
authors.affiliation: Department of Engineering and Chemical Science, Karlstad University, SE-651 88 Karlstad, Sweden.
authors.forename: Olle
authors.initials: O
authors.lastname: Stålberg
authors.affiliation: Department of Engineering and Chemical Science, Karlstad University, SE-651 88 Karlstad, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Enmark
authors.affiliation: Department of Engineering and Chemical Science, Karlstad University, SE-651 88 Karlstad, Sweden. Electronic address: jorgen.samuelsson@kau.se.
authors.forename: Jörgen
authors.initials: J
authors.lastname: Samuelsson
authors.affiliation: Department of Engineering and Chemical Science, Karlstad University, SE-651 88 Karlstad, Sweden. Electronic address: torgny.fornstedt@kau.se.
authors.forename: Torgny
authors.initials: T
authors.lastname: Fornstedt
mesh_terms: D025924:Chromatography, Supercritical Fluid / Q000295:instrumentation / Q000379:methods*; D000432:Methanol / Q000737:chemistry; D004364:Pharmaceutical Preparations / Q000032:analysis / Q000302:isolation & purification*; D011312:Pressure; D012997:Solvents / Q000737:chemistry; D013696:Temperature
chemical_list: D004364:Pharmaceutical Preparations; D012997:Solvents; D000432:Methanol
keywords: Actual conditions; Basic pharmaceuticals; Chiral separations; Design of experiments; Set conditions; Supercritical fluid chromatography