Determination of non-steroidal anti-inflammatory drugs in water samples by solid-phase microextraction based sol–gel technique using poly(ethylene glycol) grafted multi-walled carbon nanotubes coated fiber

One-pot synthesis of uniform and monodisperse superparamagnetic molecularly imprinted polymer nanospheres through a sol–gel process for selective recognition of bisphenol A in aqueous media

Uniform and monodisperse Fe₃O₄@MIP nanospheres were directly synthesized using a sol–gel method on the surface of Fe₃O₄–COOH spheres.

Zinc oxide/polypyrrole nanocomposite as a novel solid phase microextraction coating for extraction of aliphatic hydrocarbons from water and soil samples

In this work, ZnO/PPy nanocomposite coating was fabricated on stainless steel and evaluated as a novel headspace solid phase microextraction (HS-SPME) fiber coating for extraction of ultra-trace amounts of environmental pollutants; namely, aliphatic hydrocarbons in water and soil samples. The ZnO/PPy nanocomposite were prepared by a two-step process including the electrochemical deposition of PPy on the surface of stainless steel in the first step, and the synthesis of ZnO nanorods by hydrothermal process in the pores of PPy matrix in the second step. Porous structure together with ZnO nanorods with the average diameter of 70 nm were observed on the surface by using scanning electron microscopy (SEM). The effective parameters on HS-SPME of hydrocarbons (i.e., extraction temperature, extraction time, desorption temperature, desorption time, salt concentration, and stirring rate) were investigated and optimized by one-variable-at-a-time method. Under optimized conditions (extraction temperature, 65±1°C; extraction time, 15 min; desorption temperature, 250°C; desorption time, 3 min; salt concentration, 10% w/v; and stirring rate, 1200 rpm), the limits of detection (LODs) were found in the range of 0.08-0.5 μg L(-1), whereas the repeatability and fiber-to-fiber reproducibility were in the range 5.4-7.6% and 8.6-10.4%, respectively. Also, the accuracies obtained for the spiked n-alkanes were in the range of 85-108%; indicating the absence of matrix effects in the proposed HS-SPME method. The results obtained in this work suggest that ZnO/PPy can be promising coating materials for future applications of SPME and related sample preparation techniques.

Anticodeine aptamer immobilized on a Whatman cellulose paper for thin-film microextraction of codeine from urine followed by electrospray ionization ion mobility spectrometry

A combination of thin-film microextaction based on an aptamer immobilized on modified Whatman cellulose paper followed by electrospray ionization ion mobility spectrometry has been developed for the analysis of codeine in urine samples. The immobilization is based on the covalent linking of an amino-modified anticodeine aptamer to aldehyde groups of the oxidized cellulose paper. The covalent bonds were examined by infrared spectroscopy and elemental analysis. The effect of the extraction parameters, including the elution conditions (solvent type and volume), extraction time, and extraction temperature, on the extraction efficiency were investigated. Under the optimized conditions, the linear dynamic range was found to be 10-300 ng/mL with a detection limit of 3.4 ng/mL for codeine in urine. The relative standard deviation was 6.8% for three replicate measurements of codeine at 100 ng/mL in urine. Furthermore, the samples were analyzed with a standard method for the analysis of codeine using high-performance liquid chromatography with ultraviolet detection. The comparison of the results validates the accuracy of the proposed method as an alternative method for the analysis of codeine in urine samples.

New polypyrrole-carbon nanotubes-silicon dioxide solid-phase microextraction fiber for the preconcentration and determination of benzene, toluene, ethylbenzene, and o-xylene using gas liquid chromatography

For the first time, a polypyrrole-carbon nanotubes-silicon dioxide composite film coated on a steel wire was prepared by an electrochemical method. Scanning electron microscopy images showed that this composite film was even and porous. The prepared fiber was used as an absorbent for the headspace solid-phase microextraction of benzene, toluene, ethylbenzene, and o-xylene, followed by gas chromatographic analysis. This method presented an excellent performance, which was much better than that of a polypyrrole-carbon nanotube fiber. It was found that under the optimized conditions, the linear ranges were 0.01-200 ng/mL with correlation coefficients >0.9953, the detection limits were 0.005-0.020 ng/mL, the relative standard deviations were 3.9-6.4% for five successive measurements with a single fiber, and the reproducibility was 5.5-8.5% (n = 3). Finally, the developed method was successfully applied to real water samples, and the relative recoveries obtained for the spiked water samples were from 91.0 to 106.7%.

Recent advances in unique sample preparation techniques for bioanalysis

The extraction and/or purification of drugs and medicines from biological matrices are important objectives in investigating their toxicological and pharmaceutical properties. Many widely used methods such as liquid–liquid extraction or SPE, used for extracting, purifying and enriching drugs and medicines found in biological materials, involve laborious, intensive and expensive preparatory procedures, and they require organic solvents that are toxic to both humans and the environment. Recent trends are focused on miniaturization, high-throughput and automation techniques. All the advantages and disadvantages of these techniques and devices in biological analysis are presented, and their applications in the extraction and/or purification of drugs and medicines from biological matrices are discussed in this review.

Speciation analysis of aqueous nanoparticulate diclofenac complexes by solid-phase microextraction

The dynamic sorption of an organic compound by nanoparticles (NPs) is analyzed by solid-phase microextraction (SPME) for the example case of the pharmaceutical diclofenac in dispersions of impermeable (silica, SiO(2)) and permeable (bovine serum albumin, BSA) NPs. It is shown that only the protonated neutral form of diclofenac is accumulated in the solid phase, and hence this species governs the eventual partition equilibrium. On the other hand, the rate of the solid/water partition equilibration is enhanced in the presence of the sorbing nanoparticles of SiO(2) and BSA. This feature demonstrates that the NPs themselves do not enter the solid phase to any appreciable extent. The enhanced rate of attainment of equilibrium is due to a shuttle-type of contribution from the NP-species to the diffusive supply of diclofenac to the water/solid interface. For both types of nanoparticulate complexes, the rate constant for desorption (k(des)) of bound diclofenac was derived from the measured thermodynamic affinity constant and a diffusion-limited rate of adsorption. The computed k(des) values were found to be sufficiently high to render the NP-bound species labile on the effective time scale of SPME. In agreement with theoretical prediction, the experimental results are quantitatively described by fully labile behavior of the diclofenac/nanoparticle system and an ensuing accumulation rate controlled by the coupled diffusion of neutral, deprotonated, and NP-bound diclofenac species.

Fabrication of new drug imprinting polymer beads for selective extraction of naproxen in human urine and pharmaceutical samples

A drug imprinting polymer based on suspension polymerization was prepared with N,N-dimethylacrylamide and 1-(N,N-bis-carboxymethyl) amino-3-allylglycerol as functional monomers, N,N methylene diacrylamid as the cross-linker, naproxen as the template and 2,2'-azobis (2-methylbutyronitrile) as the initiator. The drug imprinted polymer was characterized by Fourier transform infrared spectroscopy, elemental analysis, thermogravimetric analysis and transmission electron microscopy. The imprinted polymer of agglomerated micro-particles with multi-pores was used for solid phase extraction. The drug imprinted polymer sorbent was selective for naproxen. The profile of the naproxen uptake by the sorbent reflects good accessibility of the active sites in the imprinted polymer sorbent. In addition, the equilibrium adsorption data of naproxen by imprinted polymer were analyzed by Langmuir isotherm models. The developed method was utilized for determination of naproxen in pharmaceutical and human urine samples by high performance liquid chromatography with satisfactory results.