212
The same method was used by Xu et al. (2016a, b) to extract proteins. The
adsorbed proteins on the Fe 3 O 4 –NH 2 @GO@DES nanoparticles were eluted with no
modification of their conformation. Also, Xu et al. (2016a, b) introduced a new type
of polymer-immobilized magnetic silica materials with high thermal stability, long
lifetime, and good durability for the extraction of trypsin. This sorbent can be recycled six times without significant loss of its extraction capacity and retained a high
extraction capacity after eight cycles (Xu et al. 2016a, b). The new synthesized
Fe 3 O 4 –NH 2 @GO@DES sorbent gave the best extraction efficiency compared to
Fe 3 O 4 –NH 2 @graphene oxide and Fe 3 O 4 –NH 2 sorbents. This was linked to the
numerous oxygen-containing functional groups existing on the surface of graphene
oxide in addition to the hydroxyl groups of deep eutectic solvent that strengthen the
interactions between proteins and deep eutectic solvent. In addition, the extraction
efficiency was the best at a certain pH where opposite charges between magnetic
microspheres and proteins exist. Another parameter related to the extraction capacity was the molecular weight of the proteins: the smaller the protein, the easier is its
extraction (Xu et al. 2016a, b).
Li et al. (2017) developed a new synthesized sorbent C 8 -amino-bifunctionalized
ordered mesoporous organosilica for the extraction of triazine herbicides from
watermelon samples. The synthesis of these new sorbents is illustrated in Fig. 6.11.
Deep eutectic solvent composed of choline chloride/ethylene glycol 1:2 molar ratio
was used as the extraction solvent. This method demonstrated lower limits of detection and relative standard deviations values in addition to high recoveries than other
methods (pressurized liquid extraction, nonaqueous cavitation extraction, molecularimprinted polymer-based solid-phase microextraction, cloud point extraction,
matrix solid-phase dispersion). These sorbents present many advantages such as
large surface area, regular and uniform pore size, and hydrothermal stability. In
addition, these sorbents have two functional groups: C 8 and amino (the octyl chains
gave the hydrophobic character, while the amino groups gave the hydrophilic one
simultaneously), which improved the adsorption selectivity of C 8 -aminobifunctionalized ordered mesoporous organosilica. The latter has a good stability
and reusability.
Online-Flow-Injection-Flame Atomic Absorption Spectrometry
Solid-Phase Extraction
Karimi et al. (2017) extracted copper and nickel metal ions from water and biological samples (human serum and urine) by synthesizing deep eutectic solvent of choline chloride/urea (1:2 molar ratio) immobilized on cotton fibers. Desorption of the
ions on deep eutectic solvent was due to the formation of a complex between nitrogen donor moieties of urea in the deep eutectic solvent and the analyte ions. This
method is characterized by its rapidity, high sampling rate, simplicity, low reagent
consumption, high accuracy, and freedom from contamination. Additionally, it presents a high advantage because it includes a natural cheap abundant renewable
L. Nakhle et al.
The same method was used by Xu et al. (2016a, b) to extract proteins. The
adsorbed proteins on the Fe 3 O 4 –NH 2 @GO@DES nanoparticles were eluted with no
modification of their conformation. Also, Xu et al. (2016a, b) introduced a new type
of polymer-immobilized magnetic silica materials with high thermal stability, long
lifetime, and good durability for the extraction of trypsin. This sorbent can be recycled six times without significant loss of its extraction capacity and retained a high
extraction capacity after eight cycles (Xu et al. 2016a, b). The new synthesized
Fe 3 O 4 –NH 2 @GO@DES sorbent gave the best extraction efficiency compared to
Fe 3 O 4 –NH 2 @graphene oxide and Fe 3 O 4 –NH 2 sorbents. This was linked to the
numerous oxygen-containing functional groups existing on the surface of graphene
oxide in addition to the hydroxyl groups of deep eutectic solvent that strengthen the
interactions between proteins and deep eutectic solvent. In addition, the extraction
efficiency was the best at a certain pH where opposite charges between magnetic
microspheres and proteins exist. Another parameter related to the extraction capacity was the molecular weight of the proteins: the smaller the protein, the easier is its
extraction (Xu et al. 2016a, b).
Li et al. (2017) developed a new synthesized sorbent C 8 -amino-bifunctionalized
ordered mesoporous organosilica for the extraction of triazine herbicides from
watermelon samples. The synthesis of these new sorbents is illustrated in Fig. 6.11.
Deep eutectic solvent composed of choline chloride/ethylene glycol 1:2 molar ratio
was used as the extraction solvent. This method demonstrated lower limits of detection and relative standard deviations values in addition to high recoveries than other
methods (pressurized liquid extraction, nonaqueous cavitation extraction, molecularimprinted polymer-based solid-phase microextraction, cloud point extraction,
matrix solid-phase dispersion). These sorbents present many advantages such as
large surface area, regular and uniform pore size, and hydrothermal stability. In
addition, these sorbents have two functional groups: C 8 and amino (the octyl chains
gave the hydrophobic character, while the amino groups gave the hydrophilic one
simultaneously), which improved the adsorption selectivity of C 8 -aminobifunctionalized ordered mesoporous organosilica. The latter has a good stability
and reusability.
Online-Flow-Injection-Flame Atomic Absorption Spectrometry
Solid-Phase Extraction
Karimi et al. (2017) extracted copper and nickel metal ions from water and biological samples (human serum and urine) by synthesizing deep eutectic solvent of choline chloride/urea (1:2 molar ratio) immobilized on cotton fibers. Desorption of the
ions on deep eutectic solvent was due to the formation of a complex between nitrogen donor moieties of urea in the deep eutectic solvent and the analyte ions. This
method is characterized by its rapidity, high sampling rate, simplicity, low reagent
consumption, high accuracy, and freedom from contamination. Additionally, it presents a high advantage because it includes a natural cheap abundant renewable
L. Nakhle et al.