Chemically bonded carbon nanotubes on modified gold substrate as novel unbreakable solid phase microextraction fiber

Fabrication of MXene/chitosan/polyurea nanocomposite decorated on a graphenized substrate for electro-enhanced solid-phase microextraction of diclofenac followed by its determination using differential pulse voltammetry

A novel solid-phase microextraction fiber based on MXene-chitosan-polyurea (MXene/CS/EPPU) nanocomposite decorated on a graphenized pencil lead fiber (MXene/CS/EPPU/GPLF) was prepared and utilized for electro-enhanced solid-phase microextraction (EE-SPME) of diclofenac (DCF) in biological samples. After extraction and desorption of DCF, it was determined by differential pulse voltammetry (DPV). For this purpose, the working electrode was prepared by deposition of the mentioned MXene/CS/EPPU nanocomposite onto the graphenized pencil lead. The synthesized SPME fiber was characterized using scanning electron microscopy and X-ray diffraction techniques. The effect of various parameters influencing the extraction and the desorption process were investigated, including applied voltage in the extraction and desorption steps, extraction and desorption times, and pH. The developed method exhibited a rather wide linearity in the range 2-1200 ng mL-1 (R2 = 0.985) for the determination of DCF in plasma samples. The limit of detection and the limit of quantification for plasma samples were estimated to be 0.58 and 1.9 ng mL-1 based on the 3Sb/m and 10Sb/m definitions, respectively. The method's accuracy and applicability have been evaluated by the analysis of plasma samples, leading to the relative recoveries in the range 87.0% and 98.0% with the relative standard deviations lower than 3.1%.

Immobilization of synthesized phenyl-enriched magnetic nanoparticles in a fabricated Y-Y shaped micro-channel containing microscaled hedges as a microextraction platform

In this survey, a reliable and applicable Y-Y shaped micro-channel in a microfluidic device was designed and manufactured. A number of micro-scaled hedges were precisely fabricated inside the micro-channel to facilitate the immobilization of synthesized core-shell Fe₃O₄@SiO₂ magnetic nanoparticles (MNPs), functionalized by triethoxyphenylsilane (TEPS) by sol-gel technique. Both sample and reagents were introduced into the microfluidic device by a syringe pump to perform the extraction and desorption steps. The functionalized MNPs were characterized by transmission electron microscopy, X-ray diffraction spectroscopy and Fourier transform infrared spectroscopy. By adopting the strategy of extraction-on-chip using this microfluidic device, we were benefited from implementing the entire analyses with the minimum amount of desorbing solvent, MNPs, and aqueous/fruit juice samples. In contrast to dispersive solid phase extraction, dispersion of MNPs during experiment is prevented by fabrication of micro-scaled hedges in the micro-channel. Consequently the stabilized MNPs are reused for the entire runs. The microfluidic device was successfully exploited as an efficient extracting plateau to evaluate the extraction/desorption capability in analysis of some organophosphorus pesticides (OPPs) as model compounds. Our results indicate that the functionalization of Fe₃O₄@SiO₂ with TEPS, improved their extraction capability due to the existence of phenyl and hydroxyl groups for more efficient π-π and hydrogen bonding interactions. Eventually, μL-scale of the organic solvent was injected into a gas chromatography-mass spectrometry system. The limits of detection (3S_b) and quantification (10S_b) for the OPPs were 0.03-0.1 and 0.1-0.35 ng mL^-1, respectively. In addition, the interday and intraday precisions were lower than 5.3% (n = 3). The obtained recovery was 95-99% for water samples and 88-96% for fruit juice samples while satisfactory regression coefficients of 0.9949-0.9991, could be achieved.

Electrospun terpolymeric nanofiber membrane for micro solid-phase extraction of diazinon and chlorpyrifos from aqueous samples

The present study deals with the synthesis and electrospining of a new terpolymer nanofiber in order to determine the amount of diazinon and chlorpyrifos in water and fruit juice samples. The synthesized terpolymer and the prepared nanofiber were characterized using ¹ H NMR spectroscopy, FTIR spectroscopy, scanning electron microscopy, and gel permeation chromatography. The performance of terpolymer nanofiber, prepared as a sorbent for micro solid phase extraction was investigated for the extraction of diazinon and chlorpyrifos from aquaeous media. Then, the target analytes were desorbed from the coating with an organic solvent and analyzed by gas chromatography with flame ionization detector. Extraction efficiencies were significant (>90%) under the optimum condition. The proposed method also demonstrated good linear dynamic ranges for diazinon and chlorpyrifos (3-250 and 5-200 µg/L), and low limit of detections (0.5 and 0.7 µg/L) respectively. Moreover, under optimum condition for extraction of diazinon and chlorpyrifos, square of correlation coefficients (R² ) of 0.9978 and 0.9953 and relative standard deviations of 4.6 and 5.1% were achieved, respectively. The recoveries for diazinon and chlorpyrifos were in the range of 85-97%.

Porous Organic Frameworks: Advanced Materials in Analytical Chemistry

Porous organic frameworks (POFs), a general term for covalent-organic frameworks (COFs), covalent triazine frameworks (CTFs), porous aromatic frameworks (PAFs), etc., are constructed from organic building monomers with strong covalent bonds and have generated great interest among researchers. The remarkable features, such as large surface areas, permanent porosity, high thermal and chemical stability, and convenient functionalization, promote the great potential of POFs in diverse applications. A critical overview of the important development in the design and synthesis of COFs, CTFs, and PAFs is provided and their state-of-the-art applications in analytical chemistry are discussed. POFs and their functional composites have been explored as advanced materials in "turn-off" or "turn-on" fluorescence detection and novel stationary phases for chromatographic separation, as well as a promising adsorbent for sample preparation methods. In addition, the prospects for the synthesis and utilization of POFs in analytical chemistry are also presented. These prospects can offer an outlook and reference for further study of the applications of POFs.

Review of geometries and coating materials in solid phase microextraction: Opportunities, limitations, and future perspectives

The development of new support and geometries of solid phase microextraction (SPME), including metal fiber assemblies, coated-tip, and thin film microextraction (TFME) (i.e. self-supported, fabric and blade supported), as well as their effects on diffusion and extraction rate of analytes were discussed in the current review. Application of main techniques widely used for preparation of a variety of coating materials of SPME, including sol-gel technique, electrochemical and electrospinning methods as well as the available commercial coatings, were presented. Advantages and limitations of each technique from several aspects, such as range of application, biocompatibility, availability in different geometrical configurations, method of preparation, incorporation of various materials to tune the coating properties, and thermal and physical stability, were also investigated. Future perspectives of each technique to improve the efficiency and stability of the coatings were also summarized. Some interesting materials including ionic liquids (ILs), metal organic frameworks (MOFs) and particle loaded coatings were briefly presented.

Application of nanocomposite-based sorbents in microextraction techniques: a review

This review provides a general overview of the recent trends for the preparation of nanocomposites and their applications in microextraction techniques.

In situ growth and phenyl functionalization of titania nanoparticles coating for solid-phase microextraction of ultraviolet filters in environmental water samples followed by high performance liquid chromatography-UV detection

Based on TiO2-nanoparticles coating fabricated by a one-step anodization method on titanium wire substrate, a novel phenyl functionalized solid-phase microextraction (SPME) fiber coating was prepared by simple and rapid in situ chemical assembling technique between the fiber surface titanol groups and trichlorophenylsilane reaction. The as-fabricated fiber exhibited good extraction capability for some UV filters and was employed to determine the ultraviolet (UV) filters in combination with high performance liquid chromatography-UV detection (HPLC-UV). The main parameters affecting extraction performance were investigated and optimized. Under the optimized conditions, the developed method was applied to detect several UV filters at trace concentration levels with only 8 mL of sample volume. They were determined in the range from 0.005 to 25 μg L(-1) with detection limits (S/N=3) from 0.1 to 50 ng L(-1). The relative standard deviations (RSDs) for single fiber repeatability varied from 4.6 to 6.5% (n=5) and fiber-to-fiber reproducibility (n=5) ranged from 5.5 to 9.1%. The linear ranges spanned two-four magnitudes with correlation coefficients above 0.9990. Five real water samples including four Yellow River water samples and one rain water sample were determined sensitively with good recoveries ranging from 86.2 to 105.5%. The functionalized fiber coating performed good reproducible manner, high mechanical strength, good stability and long service life. Moreover, this study proposed an efficient sample pretreatment method for the determination of UV filters from environmental water samples.

Self-assembly of alkyldithiols on a novel dendritic silver nanostructure electrodeposited on a stainless steel wire as a fiber coating for solid-phase microextraction

A facile and efficient electrodeposition approach for the controllable preparation of dendritic silver nanostructure was developed on an etched stainless steel (ESS) wire.

Solid phase microextraction and related techniques for drugs in biological samples

In drug discovery and development, the quantification of drugs in biological samples is an important task for the determination of the physiological performance of the investigated drugs. After sampling, the next step in the analytical process is sample preparation. Because of the low concentration levels of drug in plasma and the variety of the metabolites, the selected extraction technique should be virtually exhaustive. Recent developments of sample handling techniques are directed, from one side, toward automatization and online coupling of sample preparation units. The primary objective of this review is to present the recent developments in microextraction sample preparation methods for analysis of drugs in biological fluids. Microextraction techniques allow for less consumption of solvent, reagents, and packing materials, and small sample volumes can be used. In this review the use of solid phase microextraction (SPME), microextraction in packed sorbent (MEPS), and stir-bar sorbtive extraction (SBSE) in drug analysis will be discussed. In addition, the use of new sorbents such as monoliths and molecularly imprinted polymers will be presented.