Retention behavior of synthetic corticosteroids in packed-column supercritical fluid chromatography

Determination of selected glucocorticoids in healthy foods by ultra-performance convergence chromatography-triple quadrupole mass spectrometry

The presence of glucocorticoids in healthy foods has recently become a topic of concern because of their side effects. In this study, we developed a method based on ultra-performance convergence chromatography-triple quadrupole mass spectrometry (UPC²-MS/MS) to detect 63 glucocorticoids in healthy foods. The analysis conditions were optimized, and the method was validated. We further compared the results of this method with those of the RPLC-MS/MS method. Glucocorticoids were separated on an Acquity Torus 2-picolylamine column (100 mm × 3.0 mm, 1.7 µm) and detected via MS/MS. CO₂ and methanol (containing 0.1% formic acid) were used as mobile phases. The method demonstrated good linear relationships between 1 and 200 µg·L^-1 (R² ≥ 0.996). The limits of detection in different types of samples were 0.3-1.5 µg·kg^-1 (S/N = 3). The average recoveries (n = 9) and RSDs in different types of samples were 76.6-118.2% and 1.1-13.1%, respectively. The matrix effect, calculated as the ratio between calibration curves built in matrix and pure solvent, was less than 0.21 for both a fish oil and a protein powder. This method exhibited better selectivity and resolution than RPLC-MS/MS method. Lastly, it could realize the baseline separation of 31 isomers of 13 groups, including four groups of eight epimers. This study provides new technical support for assessing the risk of exposure to glucocorticoids in healthy foods.

High-speed screening of combinatorial libraries by gradient packed-column supercritical fluid chromatography

Packed-column supercritical fluid chromatography (pSFC) with a fast composition gradient is used as a rapid screening tool for combinatorial chemistry. The advantages of fast analysis speed and fast recovery to initial conditions are demonstrated. Retention time reproducibility is similar to isocratic analyses by pSFC and ranges from 0.37 to 0.64% relative standard deviation. A mixture of beta-blockers illustrates the 'normal phase' retention mechanism. For these solutes and a range of analytes, the peak width is relatively constant. Such behavior permits the classical peak capacity equation to be reduced to a simple, straightforward form. Using this as a performance metric, pSFC is shown to be 5-10 times faster than reversed phase HPLC for library screening.

Determination of androstenone in pig fat using packed column supercritical fluid chromatography-mass spectrometry

Packed column supercritical fluid chromatography (SFC) in combination with atmospheric pressure chemical ionisation mass spectrometry was applied to the analysis of androstenone in pig fat samples. Liquefied fat samples were dissolved in dichloromethane and analysed directly by SFC without any sample purification. Chromatographic separation was achieved with a density/pressure gradient using pure carbon dioxide as the mobile phase and the analysis resulted in a quantitation limit of 0.25 microg/g with 1 microl injection volume. Good agreement was found between the SFC method and time-resolved fluoroimmunoassay by the analysis of 15 boar back fat samples.