A nanooptosensor based on the fluorescence quenching of a composite probe was fabricated for the detection of sarafloxacin. The components of the nanocomposite fluorescent probe were a high affinity ...material of polydopamine polymer (PDA), a selective material of molecularly imprinted polymer (MIP), and optically sensitive quantum dots (QDs). The developed nanocomposite fluorescent probe exhibited excellent selectivity and sensitivity for sarafloxacin. The molecularly imprinted polymer had an imprinting factor (IF) of 8.18 and produced a probe that quenched fluorescence more effectively than a non-imprinted polymer (NIP) probe. The emission intensity of the MIP probe was linearly quenched by sarafloxacin over a range of 0.10 to 15.0 μg L
−1
with a determination coefficient (
R
2
) of 0.9966. The developed nanooptosensor had a limit of detection of 0.05 μg L
−1
. The optosensor detected sarafloxacin in chicken meat samples with recoveries ranging from 82.8 to 99.1% with an RSD below 3%. The found concentrations in spiked samples were compared well with recoveries obtained by HPLC method of detection. This developed nanooptosensor is simple to operate and cost-effective and the analytical procedure is rapid.
Graphical abstract
A composite magnetic adsorbent was developed by embedding graphene quantum dots (GQDs), silica-modified magnetite (Fe
3
O
4
-SiO
2
), and mesoporous carbon (MPC) into a molecularly imprinted polymer ...(GQDs/Fe
3
O
4
-SiO
2
/MPC/MIP). The adsorbent was applied to extract nonsteroidal anti-inflammatory drugs (NSAIDs) in milk. The MIP was formed via a sol–gel copolymerization using flurbiprofen, diflunisal, and mefenamic acid as template molecules, 3-aminopropyltriethoxysilane as a monomer, and tetraethyl orthosilicate as a cross-linker. GQDs and MPC enhanced affinity binding between NSAIDs and the adsorbent through π-π stacking, hydrogen bonding, and hydrophobic interaction. The Fe
3
O
4
-SiO
2
nanoparticles embedded in the composite adsorbent enabled its rapid isolation from the sample solution. The extracted NSAIDs were quantified by high-performance liquid chromatography and exhibited good linearity from 1.0 to 100.0 μg L
−1
for flurbiprofen and 0.5 to 100.0 μg L
−1
for diflunisal and mefenamic acid, respectively. The limits of detection ranged from 0.5 to 1.0 μg L
−1
. Recoveries of NSAIDs from spiked milk samples ranged from 81.4 to 93.7%, with RSDs below 7%. The reproducibility of the fabricated adsorbent was good and in the optimal conditions, the developed adsorbent could be used for up to six extraction-desorption cycles.
Graphical Abstract
A hierarchically porous structured composite monolith sorbent of polypyrrole-coated graphene oxide and octadecyl silica incorporated in chitosan cryogel (PPY/GOx/C18/chitosan) was synthesized and ...used as solid-phase extraction sorbent for the determination of carbamate pesticides. Various factors affecting the characteristics of the adsorbents (chemistry of the sorbent, polymerization time, concentrations of graphene oxide and octadecyl silica) and the extraction efficiency using the prepared sorbents, such as sample loading, desorption conditions, sample volume, sample flow rate, sample pH, and ionic strength, were investigated and optimized. Under the optimal conditions of sorbent preparation and extraction, the developed composite monolith sorbent provided wide linear responses from 1.0 to 500 μg L
−1
for carbofuran and diethofencarb, from 0.5 to 500 μg L
−1
for carbaryl, and from 2.0 to 500 μg L
−1
for isoprocarb. The limits of detection using HPLC-UV at 203, 220, and 208 nm were in the range of 0.5–2.0 μg L
−1
. When the composite monolith sorbent was applied for the pre-concentration and determination of carbamate in fruit juices, good recoveries (84.1–99.5%) were achieved. The developed sorbents were porous and exhibited low back pressure enabling their use at high flow rates during sample loading. Extraction and clean-up were highly efficient, and the good physical and chemical stability of the sorbent enables reuse up to 13 times.
Graphical abstract
ᅟ
A calix4arene‐functionalized graphene oxide/polydopamine‐coated cellulose acetate adsorbent was fabricated for the pre‐concentration of aflatoxins. The highly porous developed adsorbent does not ...produce the high backpressure that normally occurs in particle‐packed cartridges and its large surface area helps to improve adsorption. The highly efficient adsorption of aflatoxins by the hybrid adsorbent is facilitated via hydrogen bonding and hydrophobic and π‐π interactions. Polymerization time, amount of calix4arene‐functionalized graphene oxide, type and volume of desorption solvent, sample pH, sample volume, and sample flow rate were optimized. The linearity of aflatoxin B1 was in the range of 0.01–10.0 μg/kg, aflatoxin B2 was in the range of 0.02–10.0 μg/kg and aflatoxin G1 and aflatoxin G2 were in the range of 0.050–10.0 μg/kg. The limits of detection were 0.01 μg/kg for aflatoxin B1, 0.02 μg/kg for aflatoxin B2 and 0.05 μg/kg for aflatoxin G1 and aflatoxin G2. The developed calix4arene‐functionalized graphene oxide/polydopamine‐coated cellulose acetate adsorbent was successfully utilized for the analysis of aflatoxins from corn samples and the extraction efficiency was satisfactory with obtained recoveries from 83.0 to 106.7%. Moreover, fabricated adsorbent is easy to prepare, inexpensive, and can be reused.
Cellulose acetate fibers were modified with a gelatin cryogel adsorbent incorporating an iron–carboxylate metal–organic framework and hypercrosslinked polymer composite. The hybrid adsorption ...materials facilitated the adsorption ability toward polycyclic aromatic hydrocarbons and were entrapped into gelatin cryogel to be hierarchically coated on cellulose acetate fibers which helped to reduce the clogging problem of packed adsorbent. The composite adsorbent was employed as the solid phase of an in-syringe miniaturized solid-phase extraction system. The adsorbent was packed into the needle hub of a disposable syringe and used to extract and preconcentrate polycyclic aromatic hydrocarbons in water sample. The fabricated porous composite adsorbent was characterized and extraction conditions were optimized to achieve the best extraction performance. High-performance liquid chromatography was employed to separate and quantify extracted PAHs. The developed analysis method provided a linear range of 0.020–50 µg L
−1
for phenanthrene and benzo(b)fluoranthene, 0.010–50 µg L
−1
for pyrene, 0.0020–50 µg L
−1
for benzo(a)anthracene, and 0.0050–50 µg L
−1
for benzo(a)pyrene and dibenzo(a,h)anthracene. The limits of detection ranged from 0.5 to 5.0 ng L
−1
. Recoveries ranged from 89 to 98% with RSDs below 7%. The good stability of the adsorbent allowed up to 21 cycles of efficient extraction and desorption.
Graphical abstract
A nanocomposite fluorescent probe was fabricated for the simultaneous determination of florfenicol and sparfloxacin based on fluorescence quenching. The probe was synthesized by integrating ...nitrogen-doped graphene quantum dots (N-GQDs), cadmium telluride quantum dots (CdTe QDs) and zinc oxide nanoparticles (ZnO) into a molecularly imprinted polymer (MIP). The determination was based on the quenching of fluorescence emissions from N-GQDs by florfenicol, detected at 410 nm, and the quenching of fluorescence emissions from CdTe QDs by sparfloxacin, detected at 550 nm. The fluorescent probe was highly sensitive and specific with good linear relationships for florfenicol and sparfloxacin in the range 0.10 to 100.0 μg L
−1
. The limits of detection for florfenicol and sparfloxacin were 0.06 and 0.10 μg L
−1
, respectively. The fluorescent probe was used to determine florfenicol and sparfloxacin in food samples and the results agreed well with the results of chromatographic determination. Recoveries of spiked milk, egg and chicken samples reached 93.3–103.4% with good precision (RSD < 6%). The advantages of the nano-optosensor include high sensitivity and selectivity, simplicity, rapidity, convenience, good accuracy and precision.
Graphical Abstract
Magnetite nanoparticles incorporated into alginate beads and coated with a polypyrrole adsorbent were prepared (polypyrrole/Fe3O4/alginate bead) and used as an effective magnetic solid‐phase ...extraction sorbent for the extraction and enrichment of endocrine‐disrupting compounds (estriol, β‐estradiol and bisphenol A) in water samples. The determination of the extracted endocrine‐disrupting compounds was performed using high‐performance liquid chromatography with a fluorescence detector. The effect of various parameters on the extraction efficiency of endocrine disrupting compounds were investigated and optimized including the type and amount of sorbent, sample pH, extraction time, stirring speed, and desorption conditions. Under optimum conditions, the calibration curves were linear in the concentration range of 0.5–100.0 μg/L, and the limit of detection was 0.5 μg/L. The developed method showed a high extraction efficiency, the recoveries were in the range of 90.5 ± 4.1 to 98.2 ± 5.5%. The developed sorbent was easy to prepare, was cost‐effective, robust, and provided a good reproducibility (RSDs < 5%), and could be reused 16 times. The developed method was successfully applied for the determination of endocrine‐disrupting compounds in water samples.
A hierarchical porouscomposite magnetic sorbent was fabricated and applied to the dispersive solvent‐assisted solid‐phase extraction of five polycyclic aromatic hydrocarbons. A sorbent was first ...prepared by incorporating graphene oxide, calcium carbonate, and magnetite nanoparticles into a polyvinyl alcohol cryogel. The graphene oxide was converted to reduced graphene oxide using ascorbic acid and a hierarchical porous structure was produced by reacting hydrochloric acid with incorporated calcium carbonate to generate carbon dioxide bubbles which created a second network. Before extracting the target analytes, the extraction solvent was introduced into the hierarchical pore network of the sorbent. The extraction was based on the partition between the analytes and introduced extraction solvent and the adsorption of analytes on reduced graphene oxide.The extraction efficiency was enhanced through π‐π and hydrophobic interactions between polycyclic aromatic hydrocarbons and reduced graphene oxide and extraction solvent. The extracted polycyclic aromatic hydrocarbons were determined by using high‐performance liquid chromatography coupled with a fluorescence detector. The developed method was applied to extract polycyclic aromatic hydrocarbons in disposable diaper, coffee, and tea samples and recoveries from 84.5 to 99.4% were achieved with relative standard deviations below 7%. The developed sorbent exhibited good reproducibility and could be reused for 10 cycles.The developed sorbent exhibited good reproducibility and could be reused for 10 cycles.The developed sorbent exhibited good reproducibility and could be reused for 10 cycles.
Magnetite nanoparticles coated with silica and hydrophobic octadecyl layers were successfully synthesized and used in magnetic solid phase extraction of tetracyclines from water samples. The ...magnetite nanoparticles facilitated a convenient magnetic separation of sorbent from an aqueous sample, the octadecyl layer helped to enhance the adsorption ability and the silica layer helped to prevent the aggregation of the magnetite nanoparticles. The effect of various parameters on the extraction efficiency were optimized including the amount of sorbent, sample pH, stirring rate, extraction time and desorption conditions. Under the optimum conditions, the recoveries were in the range of 82 to 88%, the calibration curves were linear over the concentration range of 0.002 to 1.0 μg/mL for oxytetracycline and 0.01 to 1.0 μg/mL for tetracycline and chlortetracycline, respectively. The developed method had several advantages such as simplicity, convenience, cost-effectiveness and high extraction efficiency.
