Salting-out strategy for speciation of selenium in aqueous samples using centrifuge-less dispersive liquid-liquid microextraction.

The centrifuge-less dispersive liquid-liquid microextraction (DLLME) technique was used to separate selenium species in aqueous samples. According to the salting-out effect, a simple approach was used to eliminate the centrifugation step. The optimization of the independent variables was performed using chemometric methods. Under optimal conditions, this methodology was statistically validated. The linearity was between 20 and 300 µg L-1. The limit of detection and quantification were calculated 3.4 µg L-1 and 10.4 µg L-1, respectively. The values of reproducibility and repeatability were determined ≤ 9.5% and ≤ 6.4, respectively. The possibility of the method was successfully assessed by analyzing the analytes in real samples clarified satisfactory recoveries (98.1-101.4% for Se (IV) and 98.4-101.5% for Se (VI)).

Magnetic nanoparticles modified with organic dendrimers containing methyl methacrylate and ethylene diamine for the microextraction of rosuvastatin.

Magnetic nanoparticles (MNPs) modified with organic dendrimers are shown to be a viable sorbent of the microextraction of the drug rosuvastatin (RST; also known as Crestor). The MNPs were prepared from iron(II) chloride and iron(III) chloride and then coated with silicon dioxide. The coated MNPs produced by this method have diameters ranging from 10 to 60 nm according to scanning electron microscopy. The MNPs were further modified with organic dendrimers containing methyl methacrylate and ethylene diamine. The resulting MNPs were characterized by SEM, Fourier transform infra-red and thermal gravimetry analysis. Then, the efficacy of the modified MNPs with respect to the extraction of RST was studied. The adsorption of RST by MNPs can be best described by a Langmuir isotherm. Following elution with buffer, RST was quantified by HPLC. The method was applied to the determination of RST in (spiked) human blood plasma, urine, and in tablets. RST extraction efficiencies are 54.5% in plasma, 86.6% from the drug matrix, and 94.3% in urine. The highest adsorption capacity of the RST by the MNPs adsorbent was 61 mg⋅g-1. Graphical abstract Co-precipitation was used to synthesize magnetic nanoparticles (MNPs). They were coated with a layer of SiO2 and then branched by organic dendrimers containing methyl methacrylate (MMA) and ethylene diamine (EDA). Rosuvastatin (RST) drug was trapped between dendrimer branches, therefore adsorption capacity of the drug was strongly increased.

Rapid screening of oleuropein from olive leaves using matrix solid-phase dispersion and high-performance liquid chromatography.

Matrix solid-phase dispersion (MSPD) methodology as a quick and easy extraction method has been developed to extract oleuropein from Olea europaea leaves. This method has been compared with conventional maceration and Soxhlet extraction (SOXE) methods. Variables affecting MSPD, such as the sorbent material, the ratio of sample to sorbent material, elution solvent, and volume of the elution solvent, have been fully evaluated and optimized. Oleuropein was successfully extracted by silica sorbent with 350 microL of dichloromethane-methanol (70 + 30, v/v) as the elution solvent. The calibration curve showed good linearity (r2 = 0.9985) and precision (RSD <4.5%) in the concentration range of 0.5-100 microg/mL for oleuropein. The LOD and LOQ were 0.14 and 0.5 microg/mL, respectively. The recoveries were in the range of 88.0-94.0% with RSD values ranging from 6.0 to 9.8%. The extraction yields obtained by the MSPD method were comparable with those obtained by the maceration and SOXE methods. The reported MSPD extraction method was revealed to be eco-friendly, simpler, and faster than conventional methods used to quantify oleuropein in O. europaea leaves.

Validation of chemometric-assisted single-drop microextraction based on sustainable solvents to analyze polyaromatic hydrocarbons in water samples.

Chemometric and statistic approaches were applied to optimize and validate headspace-single drop microextraction-based deep eutectic solvents combined with gas chromatography-mass spectrometry. The proposed technique was used for the pre-concentration, separation, and detection of polyaromatic hydrocarbons in aqueous samples. The efficacy of the independent variables on the extraction efficiency was studied via chemometric methods in two steps. The method exhibits good linearity for the analytes (R2 ≥ 0.9989). Under optimal conditions, the analytical signal was linear in the range of 0.01-50 µg L-1. The limit of detection and limit of quantitation were evaluated in the concentration range of 0.003-0.012 and 0.009-0.049 µg L-1, respectively. The precision consisting of repeatability and reproducibility were assessed by estimating the relative standard deviation (RSD%), and their values were found to be lower than 7.1% and 11.7%, respectively. Consequently, the proposed procedure was used to extract and analyze 19 polyaromatic hydrocarbons in real aqueous samples, which demonstrated satisfactory recoveries (94.40-105.98%).

Deep eutectic solvent-based headspace single-drop microextraction of polycyclic aromatic hydrocarbons in aqueous samples.

An improved deep eutectic solvent (DES)-based headspace single-drop microextraction procedure has been developed as a green procedure for gas chromatography-mass spectrometric analysis of polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. The stability of the micro-drop was significantly improved using a DES as an extraction phase and a bell-shaped tube as a supporter. These strategies helped to perform the extraction process in higher temperatures and stirring rates. Finally, the back-extraction of the analytes into a proper solvent that is compatible with the chromatography system was applied. The efficacy of the independent variables on the extraction efficiency was evaluated via chemometric methods in two steps. The best result was obtained with choline chloride-oxalic acid at the molar ratio of 1:2, a stirring speed of 2000 rpm for 10 min as well as a sample temperature of 50 °C and with ionic strength prepared by using a 10% (w/v) NaCl. The method indicated a good linearity for the analytes (R2≥0.9989). Under optimal conditions, the analytical signal was linear in the range of 0.01-50 µg L-1. Limit of detection (LOD) and limit of quantification (LOQ) were evaluated at the concentration levels of 0.003-0.012 and 0.009-0.049 µg L-1, respectively. Intraday and interday precision for all targeted compounds was less than 7.2% and 11.3%, respectively. Consequently, the proposed procedure was efficiently applied to extract and analyze the 16 target compounds in real aqueous samples representing satisfactory recoveries (94.40-105.98%).

Corrigendum to "Polythiophene-Chitosan Magnetic Nanocomposite as a Highly Efficient Medium for Isolation of Fluoxetine from Aqueous and Biological Samples".

[This corrects the article DOI: 10.1155/2016/2921706.].

Synthesis of high generation thermo-sensitive dendrimers for extraction of rivaroxaban from human fluid and pharmaceutic samples.

In this present study, poly (N-isopropylacrylamide) as a thermo-sensitive agent was grafted onto magnetic nanoparticles, then ethylenediamine and methylmethacrylate were used to synthesize the first generation of poly amidoamine (PAMAM) dendrimers successively and the process continued alternatively until the ten generations of dendrimers. The synthesized nanocomposite was investigated using Fourier transform infrared spectrometry, thermalgravimetry analysis, X-ray diffractometry, elemental analysis and vibrating-sample magnetometer. The particle size and morphology were characterized using dynamic light scattering, field emission scanning electron microscopy and transmission electron microscopy. Batch experiments were conducted to investigate the parameters affecting adsorption and desorption of rivaroxaban by synthesized nanocomposite. The maximum sorption of rivaroxaban by the synthesized nanocomposite was obtained at pH of 8. The resulting grafted magnetic nanoparticle dendrimers were applied for extraction of rivaroxaban from biologic human liquids and medicinal samples. The specifications of rivaroxaban sorbed by a magnetic nanoparticle dendrimer showed good accessibility and high capacity of the active sites within the dendrimers. Urine and drug matrix extraction recoveries of more than 92.5 and 99.8 were obtained, respectively.

Modified Magnetic Nanoparticles as a Novel Sorbent for Dispersive Magnetic Solid-Phase Extraction of Triazine Herbicides in Aqueous Media.

In this study, a polythiophene/chitosan polymer and electrospinning polymer nanofibers as modifier compounds were used, and magnetic nanocomposites as a novel adsorbent were proposed, for the preconcentration of some triazines, including atrazine, ametryn, and terbutryn, in aqueous samples before GC. The synthesized magnetic nanoparticles, magnetic polymer nanofibers, and polythiophene magnetic nanocomposite were characterized by scanning electron microscopy. The separation of the target analytes from the aqueous solution containing the triazines and different magnetic nanocomposites were simply achieved by applying an external magnetic field. The extraction efficiency of magnetic polyamide nanofibers was enhanced as compared with other modified magnetic nanoparticles. The main factors affecting the extraction efficiency, including desorption conditions, nanocomposite component ratio, electrospinning time, sorbent amount, extraction time, ionic strength, and sample pH, were optimized. The developed method proved to be convenient and offers sufficient sensitivity and good reproducibility. Under optimized conditions, the method's LOD (S/N = 3) and LOQ (S/N = 10) were 1-5 and 15 ng L-1, respectively; good linearity was obtained within the range of 15-2000 ng L-1 for triazines, with correlation coefficients >0.9997. The RSD at the concentration level of 100 ng L-1 was 9-14% (n = 3). Furthermore, the method was successfully applied to the determination of triazines in real samples, in which relative recoveries of 98-103% were obtained. Compared with other methods, the current method is characterized by its ease, fast separation, and low detection limits.

Polythiophene-Chitosan Magnetic Nanocomposite as a Highly Efficient Medium for Isolation of Fluoxetine from Aqueous and Biological Samples.

Polythiophene/chitosan magnetic nanocomposite as an adsorbent of magnetic solid phase extraction was proposed for the isolation of fluoxetine in aqueous and biological samples prior to fluorescence detection at 246 nm. The synthesized nanoparticles, chitosan and polythiophene magnetic nanocomposite, were characterized by scanning electron microscopy, FT-IR, TGA, and EDAX. The separation of the target analyte from the aqueous solution containing the fluoxetine and polythiophene/chitosan magnetic nanocomposite was simply achieved by applying external magnetic field. The main factors affecting the extraction efficiency including desorption conditions, extraction time, ionic strength, and sample solution pH were optimized. The optimum extraction conditions were obtained as 10 min for extraction time, 25 mg for sorbent amount, 50 mL for initial sample volume, methanol as desorption solvent, 1.5 mL for desorption solvent volume, 3 min for desorption time, and being without salt addition. Under the optimum conditions, good linearity was obtained within the range of 15-1000 µg L(-1) for fluoxetine, with correlation coefficients 0.9994. Furthermore, the method was successfully applied to the determination of fluoxetine in urine and human blood plasma samples. Compared with other methods, the current method is characterized with highly easy, fast separation and low detection limits.

Rapid monitoring of carvacrol in plants and herbal medicines using matrix solid-phase dispersion and gas chromatography flame ionisation detector.

Matrix solid-phase dispersion (MSPD) method coupled with gas chromatography flame ionisation detector as a quick and easy extraction technique has been developed to extract carvacrol from plants and herbal medicines. Influence of important parameters on the MSPD method efficiency, such as the sorbent material, the ratio of sample to sorbent material, elution solvent and volume of the elution solvent has been evaluated and optimised. Carvacrol was successfully extracted by diatomaceous earth as sorbent with 350 µL of dichloromethane as elution solvent. The calibration curve showed good linearity (r(2) = 0.9965) and precision (RSD < 8.16%) in the concentration range of 0.5-100 µg mL(-1) for carvacrol. The limit of detection and limit of quantification were 0.1 and 0.5 µg mL(-1), respectively. The recoveries were in the range of 74.4-80.5% with relative standard deviation (RSD) values ranging from 8.4% to 9.8%. The reported MSPD extraction method revealed to be simpler and faster than conventional methods used to quantify carvacrol from plants and herbal medicines.

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.