Off-line coupling of subcritical water extraction with subcritical water chromatography via a sorbent trap and thermal desorption

In this study, the off-line coupling of suberitical water extraction (SBWE) with subcritical water chromatography (SBWC) was achieved using a sorbent trap and thermal desorption. The sorbent trap was employed to collect the extracted analytes during subcritical water extraction. After the extraction, the trap was connected to the subcritical water chromatography system, and thermal desorption of the trapped analytes was performed before the SBWC run. The thermally desorbed analytes were then introduced into the subcritical water separation column and detected by a UV detector. Anilines and phenols, were extracted from sand and analyzed using this off-line coupling technique. Subcritical water extraction of flavones from orange peel followed by subcritical water chromatographic separation was also investigated. The effects of water volume and extraction temperature on flavone recovery were determined. Because a sorbent trap was used to collect the extracted analytes, the sensitivity of this technique was greatly enhanced as compared to that of suberitical water extraction with solvent trapping. Since no organic solvent-water extractions were necessary prior to analysis, this technique eliminated any use of organic solvents in both extraction and chromatography processes.