Dynamic pressurized hot solvent extraction

As can be seen from Fig. 6.9, dynamic pressurized hot solvent extraction (DPHSE) has evolved similarly to ASE however, as noted earlier, DPHSE has been the subject of many fewer reports, primarily as a result of the lack of commercially available equipment for implementation. In any case, the relatively scant reported applications of DPHSE are of especial interest as regards automation of the analytical process in fact, the dynamic nature of the system facilitates its coupling to other dynamic systems with a view to accomplishing preconcentration [39,42,45,145], filtration [42,45], chromatographic separation [145,146], derivatization [46,57] and detection [44,147], among others, and the partial or total automation of the analytical process. 

Fig. 6.10. Typical experimental set-up for dynamic pressurized hot solvent extraction (DPHSE). SR solvent reservoir, HPP high-pressure pump, IV inlet valve, OV outlet valve, PH pre-heater, EC extraction cell, C cooler, R restrictor.

The steps involved in a dynamic pressurized hot solvent extraction process are similar to those of ASE, with only a few, slight differences — particularly at the last stages. Thus, the DPHSE process involves the following five steps (see Fig. 6.13) ... 

A hot water dynamic extraction device was constructed using the solubilization apparatus of Miller and Hawthorne (10) as a model and was used for pressurized extraction of milk thistle seed meal. Figure 2 shows a schematic diagram of the apparatus. Water, the extraction solvent, was pressurized and pumped using a Bio-Rad 2800 HPLC solvent delivery system (Hercules, C A) to an extraction cell housed in the oven of a Hewlett-Packard 5890 gas chromatography (GC) oven (Wilmington, DE). Before... 

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