extracts containing co-extracted elements of the matrix. Nevertheless, to overcome
this problem, modern analytical techniques include strategies such as the reduction
of the sample quantities, the lower solvent consumption, or the reduction of the
extraction time, to favor the reduction of unwanted components of the matrix. The
most used clean-up processes are SPE and d-SPE which allow to obtain fairly clear
extracts. However, the skip of this step could improve the recoveries of some
compounds that are retained by the SPE adsorbents. LC-MS is usually the instrumental analysis performed, thanks to its ability to achieve low limits of quantification and detection, good repeatability, and reproducibility [7, 121]. Indeed, LC-MS/
MS have been the instrumental analysis with great confidence to confirm the
analytes and its capability to reach very low limits of detection and quantification
[122, 123]. All details for each extraction methodology for pharmaceuticals in plants
are reported in Table 6.
5.1 Assisted Solvent Extraction (ASE)
In order to perform a good extraction by means of ASE, the selection of an
appropriate organic solvent as well as temperature is crucial. In fact, ASE provides
the advantage to choose between several solvents allowing to extract compounds of
different families in different matrices [124]. ASE uses temperature and pressure in
its procedure, which means that modification on the solvent physico-chemical
properties occurs facilitating the release of pharmaceuticals. As an example, solvent
density decreases allowing a more extensive wet into the sample, whereas solvent
boiling point increases due to the effect of the pressure [124]. However, high
temperatures could deteriorate the PhACs, especially the thermolabile ones; then, a
compromise between enhance on the extraction efficiency and the temperature is
established. First, a dispersing agent (sand, hydromatrix, or Florisil) is mixed with
the sample in order to avoid sample agglomerates, obtaining a greater surface and,
consequently, facilitating the solvent interaction. Moreover, Florisil is the dispersant
agent more used before the extraction starts, in order to improve the extraction
efficiency through the adsorption of sugar and waxes with the subsequent retention
[125, 126]. Samples are placed in a stainless-steel extraction cell and capped with
filters at both ends to retain the sample into the cell but letting out the extraction
solvent containing the extracted compounds [127]. Once the solvent is introduced
into the system (different volumes could be employed), the extraction cell is placed
in the oven, and the system starts setting the desired temperature and pressure.
Another important parameter to consider consists of the time and cycles used, as
the more time the solvent is in contact with the sample, the more extraction
efficiency is performed. However, the co-extractive compounds are also released.
Then, a compromise between time and extraction efficiency is created and should be
optimized [124]. SPE was usually performed as the clean-up step after the extraction,
removing interferences and obtaining cleaner extracts [74, 128]. For this reason, it is
easier to adjust the pressure than the temperature of the ASE [128, 129]. Similar to
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R. Manasfi et al.
this problem, modern analytical techniques include strategies such as the reduction
of the sample quantities, the lower solvent consumption, or the reduction of the
extraction time, to favor the reduction of unwanted components of the matrix. The
most used clean-up processes are SPE and d-SPE which allow to obtain fairly clear
extracts. However, the skip of this step could improve the recoveries of some
compounds that are retained by the SPE adsorbents. LC-MS is usually the instrumental analysis performed, thanks to its ability to achieve low limits of quantification and detection, good repeatability, and reproducibility [7, 121]. Indeed, LC-MS/
MS have been the instrumental analysis with great confidence to confirm the
analytes and its capability to reach very low limits of detection and quantification
[122, 123]. All details for each extraction methodology for pharmaceuticals in plants
are reported in Table 6.
5.1 Assisted Solvent Extraction (ASE)
In order to perform a good extraction by means of ASE, the selection of an
appropriate organic solvent as well as temperature is crucial. In fact, ASE provides
the advantage to choose between several solvents allowing to extract compounds of
different families in different matrices [124]. ASE uses temperature and pressure in
its procedure, which means that modification on the solvent physico-chemical
properties occurs facilitating the release of pharmaceuticals. As an example, solvent
density decreases allowing a more extensive wet into the sample, whereas solvent
boiling point increases due to the effect of the pressure [124]. However, high
temperatures could deteriorate the PhACs, especially the thermolabile ones; then, a
compromise between enhance on the extraction efficiency and the temperature is
established. First, a dispersing agent (sand, hydromatrix, or Florisil) is mixed with
the sample in order to avoid sample agglomerates, obtaining a greater surface and,
consequently, facilitating the solvent interaction. Moreover, Florisil is the dispersant
agent more used before the extraction starts, in order to improve the extraction
efficiency through the adsorption of sugar and waxes with the subsequent retention
[125, 126]. Samples are placed in a stainless-steel extraction cell and capped with
filters at both ends to retain the sample into the cell but letting out the extraction
solvent containing the extracted compounds [127]. Once the solvent is introduced
into the system (different volumes could be employed), the extraction cell is placed
in the oven, and the system starts setting the desired temperature and pressure.
Another important parameter to consider consists of the time and cycles used, as
the more time the solvent is in contact with the sample, the more extraction
efficiency is performed. However, the co-extractive compounds are also released.
Then, a compromise between time and extraction efficiency is created and should be
optimized [124]. SPE was usually performed as the clean-up step after the extraction,
removing interferences and obtaining cleaner extracts [74, 128]. For this reason, it is
easier to adjust the pressure than the temperature of the ASE [128, 129]. Similar to
450
R. Manasfi et al.