In SPME, the extractant phase consists of a small volume of sorbent material
(μL), which is a solid or semi-solid polymer in many cases. The analytes are
extracted in the extractant phase and desorbed by temperature or organic solvent,
depending on the subsequent analytical technique [59, 60, 104]. If gas chromatography (GC) is selected, the desorption is thermal, and if the technique is highperformance liquid chromatography (HPLC), the desorption is with an organic
solvent. It can be carried out both in static and dynamic modes. The interaction
with the aqueous matrix can occur via adsorption or absorption, according to the
nature of the extractant material.
In static SPME, the fiber variant (IF-SPME) [59, 90, 97, 104], in stir bar (SBSE)
[58, 96], with rotating disk (RDSE) [45, 98], dispersive (DSPME) [60, 115]
methods, including magnetic particle dispersion (MSPM) [92], have been used.
Dynamic SPME has been used in the tube-denominated variant (IT-SPME) [55, 95].
In the IF-SPME, a solid rod (1–2-cm-long) of very small diameter (fiber) is coated
with the sorbent (~100 μL). The fiber is attached to a stainless steel piston covered by
a protective needle that is adapted to a syringe. The plunger causes the fiber to come
into contact with the sample. The analytes are transported from the aqueous matrix to
the coating until equilibrium is reached [59, 90, 97, 104]. Therefore, extraction
occurs in the outer phase of the fiber. Once the equillibrium is reached, the fiber is
removed from the solution, and the analytes are desorbed in the detection equipment
itself [59].
The SBSE uses magnetic glass-coated stir bars and is subsequently wrapped with
a film (50–300 μL) of sorbent material [58, 96]. In the RDSE, a rotating Teflon or
silica disk coated on one of its surfaces instead of a stir bar is used by the material
and constitutes the extraction phase [45]. In some cases, the entire disk consists of
the sorbent material [98]. The contact area is larger than in the case of SBSE; it can
be stirred at higher speeds, and lower detection limits are achieved [45, 98]. In the
RDSE, the disk does not touch the bottom of the container, which prevents cracking
that occurs in the lining due to friction, which occurs in the SBSE. On the other hand,
the extraction times are shorter than in the SBSE [98].
The DSPME, also known as DSPE, is based on the direct addition of the sorbent
(insoluble) material in the aqueous solution containing the analytes followed by
dispersion to favor their contact with the sorbent [60, 115, 124]. Upon completion of
the sorption process, the sorbent containing the analytes retained on its surface is
separated by filtration or centrifugation. Interferences are easily removed by elution
with suitable solvents [60, 115, 124]. Sorbent particles can be chemically modified
to improve selectivity for analytes of interest [99, 100]. If the sorbent material
consists of inorganic magnetic particles coated with silicon dioxide (SiO 2 ), aluminum oxide (Al 2 O 3 ), or polymeric materials, they can be separated with a magnet.
The technique is then called magnetic solid phase microextraction (MSPE) [92] and
is simpler and cheaper than the common DSPME [124]. The most attractive property
of the DSPME is its small extraction time [115, 124].
In the IT-SPME the extractive phase is placed inside a very small hollow capillary
tube consisting of molten silica [55, 95, 97] through which the sample moves.
Sorption is performed in the internal phase of the tube. The extractive phase may
Quantification of Non-steroidal Anti-inflammatory Drug in Water
93
(μL), which is a solid or semi-solid polymer in many cases. The analytes are
extracted in the extractant phase and desorbed by temperature or organic solvent,
depending on the subsequent analytical technique [59, 60, 104]. If gas chromatography (GC) is selected, the desorption is thermal, and if the technique is highperformance liquid chromatography (HPLC), the desorption is with an organic
solvent. It can be carried out both in static and dynamic modes. The interaction
with the aqueous matrix can occur via adsorption or absorption, according to the
nature of the extractant material.
In static SPME, the fiber variant (IF-SPME) [59, 90, 97, 104], in stir bar (SBSE)
[58, 96], with rotating disk (RDSE) [45, 98], dispersive (DSPME) [60, 115]
methods, including magnetic particle dispersion (MSPM) [92], have been used.
Dynamic SPME has been used in the tube-denominated variant (IT-SPME) [55, 95].
In the IF-SPME, a solid rod (1–2-cm-long) of very small diameter (fiber) is coated
with the sorbent (~100 μL). The fiber is attached to a stainless steel piston covered by
a protective needle that is adapted to a syringe. The plunger causes the fiber to come
into contact with the sample. The analytes are transported from the aqueous matrix to
the coating until equilibrium is reached [59, 90, 97, 104]. Therefore, extraction
occurs in the outer phase of the fiber. Once the equillibrium is reached, the fiber is
removed from the solution, and the analytes are desorbed in the detection equipment
itself [59].
The SBSE uses magnetic glass-coated stir bars and is subsequently wrapped with
a film (50–300 μL) of sorbent material [58, 96]. In the RDSE, a rotating Teflon or
silica disk coated on one of its surfaces instead of a stir bar is used by the material
and constitutes the extraction phase [45]. In some cases, the entire disk consists of
the sorbent material [98]. The contact area is larger than in the case of SBSE; it can
be stirred at higher speeds, and lower detection limits are achieved [45, 98]. In the
RDSE, the disk does not touch the bottom of the container, which prevents cracking
that occurs in the lining due to friction, which occurs in the SBSE. On the other hand,
the extraction times are shorter than in the SBSE [98].
The DSPME, also known as DSPE, is based on the direct addition of the sorbent
(insoluble) material in the aqueous solution containing the analytes followed by
dispersion to favor their contact with the sorbent [60, 115, 124]. Upon completion of
the sorption process, the sorbent containing the analytes retained on its surface is
separated by filtration or centrifugation. Interferences are easily removed by elution
with suitable solvents [60, 115, 124]. Sorbent particles can be chemically modified
to improve selectivity for analytes of interest [99, 100]. If the sorbent material
consists of inorganic magnetic particles coated with silicon dioxide (SiO 2 ), aluminum oxide (Al 2 O 3 ), or polymeric materials, they can be separated with a magnet.
The technique is then called magnetic solid phase microextraction (MSPE) [92] and
is simpler and cheaper than the common DSPME [124]. The most attractive property
of the DSPME is its small extraction time [115, 124].
In the IT-SPME the extractive phase is placed inside a very small hollow capillary
tube consisting of molten silica [55, 95, 97] through which the sample moves.
Sorption is performed in the internal phase of the tube. The extractive phase may
Quantification of Non-steroidal Anti-inflammatory Drug in Water
93