A novel means of achieving chiral separations in supercritical fluid chromatography (SFC) using a water stationary phase is presented. By adding various chiral selectors to the phase, different chiral analytes can be readily separated using neat CO 2 as a mobile phase. For example, by adding β-cyclodextrin it is found that certain flavanone enantiomers can be separated, while using the antibiotic vancomycin as a selector provides separation of some chiral phenoxypropionic acids. Other additives such as sodium chloride and triethylamine are also explored and found to enhance certain separations when also present in the water phase. While column pressure has a moderate impact on chiral analyte retention and separation in this SFC method, column temperature has a comparatively larger influence. In particular, relatively cooler temperatures below about 5 o C are found to markedly increase resolution and selectivity. For instance, notably large resolution of 4.7 is achieved for a phenoxypropionic acid pair at 0 o C and 150 atm CO 2. Since the method does not require modifier to elute such polar species, it is also readily compatible with FID detection and does not generate organic waste. Therefore, results indicate that this approach could be a potentially simple and flexible means of achieving chiral separations in SFC.

The use of a novel micro pressurized liquid extraction (µPLE) method for the isolation of 16 priority pollutant polycyclic aromatic hydrocarbons (PAHs) from various solid samples is explored. The technique employs rapid heating in a single static extraction mode to remove analytes in a matter of seconds from 5-10 mg samples using only 125 µL of solvent. For example, results show that 30 s extractions with toluene at 200 °C produce respective PAH recovery ranges of 90%-130% and 88%-114% from samples of soil and smoked chicken. Comparatively, solids containing significant amounts of biochar were more challenging to extract from. For instance, when using a pure biochar sample matrix, recoveries for the 16 PAHs range from only 33%-66% after 60 s of extraction with toluene at 200 °C. Overall, these extraction results agree very well with those reported when using conventional methods on similar samples. Therefore, the findings indicate that µPLE can potentially provide an alternative sample preparation method for PAHs that is both very rapid and requires little solvent.

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