pH Of Sample Solution Research Articles

Preconcentration and ICP-OES determination of rare earth elements using silicas chemically modified with aminophosphonic groups in fossil raw materials

ABSTRACT Silica-based adsorbents (Silica gel 60 and Silochrom S-80) chemically modified with aminophosphonic groups with various surface concentrations have been proposed for the preconcentration of rare earth elements (REE). The resulting adsorbents were studied by FT-IR, SEM, TGA and compared with unmodified matrices. Adsorbents quantitatively extracted REE from solutions with pH 1.0–5.0. Solid phase extraction at pH 1.0–2.0 made it possible to quantitatively separate rare earth elements from the predominant amounts of accompanying metal ions. An increase in the concentration of aminophosphonic groups on the silica surface led to an increase in the adsorption capacity of the adsorbent for Gd(III) both in batch and dynamic modes. A technique for solid-phase extraction followed by inductively coupled plasma optical emission (SPE-ICP-OES) determination of REE has been developed; it includes pumping 200 mL of the sample solution (pH 1) through a mini-column with an adsorbent at a flow rate of 1 mL min−1, eluting REE with 10 mL of 1 M HNO3 (preconcentration factor 20), and then determination of the elements in the eluate by ICP-OES. The technique was used for the determination of REE in lignite and coal from the Krasnoyarsk Krai (Russia). The accuracy of the results was confirmed by comparison with ICP-MS determination and by the analysis of certified reference material of coal ash.

Optimisation of the Extraction Process of Naringin and Its Effect on Reducing Blood Lipid Levels In Vitro

The naringin extraction process was optimised using response surface methodology (RSM). A central component design was adopted, which included four parameters: extraction temperature (X1), material-liquid ratio (X2), extraction time (X3), and ultrasonic frequency (X4) of 74.79 °C, 1.58 h, 1:56.51 g/mL, and 28.05 KHz, respectively. Based on these optimal extraction conditions, naringin was tested to verify the model's accuracy. Naringin yield was 36.2502 mg/g, which was equivalent to the predicted yield of 36.0124 mg/g. DM101 macroporous adsorption resin was used to purify naringin. The effects of loading concentration, loading flow rate, and sample pH on the adsorption rate of naringin and the effect of ethanol concentration on the desorption rate of naringin were investigated. The optimum conditions for naringin purification using macroporous resins were determined. The optimal loading concentration, sample solution pH, and loading flow rate were 0.075 mg/mL, 3.5, and 1.5 mL/min, respectively. Three parallel tests were conducted under these conditions, and the average naringin yield was 77.5643%. Naringin's structure was identified using infrared spectroscopy and nuclear magnetic resonance. In vitro determination of the lipid-lowering activity of naringin was also conducted. These results showed that naringin has potential applications as a functional food for lowering blood lipid levels.

Isolation of organophosphate pesticides from water using gold nanoparticles doped magnetic three-dimensional graphene oxide

Pesticides are a large group of pristine organic contaminants, which are widely discharged into environmental water due to agricultural activities. Hence, extraction, determination, and removal of pesticides from water resources are necessary for human health. In this study, novel adsorbent was developed based on three-dimensional magnetic graphene coated with gold nanoparticles (3D-MG@AuNPs) for extraction of chlorpyrifos, dicrotophos, fenitrothion, and piperophos as four specific organophosphorus pesticides (OPPs) from wastewater and tap water samples. The proposed nanocomposite was characterized; FTIR and EDX are performed for the expected functional groups and elemental analysis, SEM showed the unique and spherical AuNPs are well dispersed over graphene sheets. In this investigation, the important parameters that have effect on the extraction efficiency, including the desorbing solvent, desorbing solvent volume, vortex time, the extraction time, adsorbent dosage, pH of sample solutions, and salt effect were evaluated. In conclusion, the measured amounts of the chosen OPPs were determined using the gas chromatography microelectron capture (μECD-GC) method. Limits of quantification (S/N ratio of 10) and detection (S/N ratio of 3) were attained at concentrations of 0.26–0.43 μg.L−1 and 0.08–0.14 μg.L−1, respectively. According to the results of the investigations, the synthesized 3D-MG@AuNPs did not require any complicated sample preparation methods; therefore, it is a very good choice for solid magnetic phase extraction studies.

Preconcentrations of Pb(II), Ni(II) and Zn(II) by solid phase bio-extractor using thermophilic Bacillus subtilis loaded multiwalled carbon nanotube biosorbent

An alternative biotechnological solid phase bio-extraction (SPE) method was developed. Bacillus subtilis loaded multiwalled carbon nanotube was designed and used as biosorbent for the preconcentrations of Pb(II), Ni(II), and Zn(II). The experimental parameters such as sample flow rate, pH of sample solution, amounts of Bacillus subtilis and multiwalled carbon nanotube, volume of sample solution and reusability of column which affects the analytical characteristics of the SPE method were investigated in details. Surface structures were examined by using FTIR, SEM. The best pH was determined as 5.0 and the percentages recoveries of Zn(II), Ni(II), and Pb(II) were determined as 99.1%, 98.7%, and 96.2%, respectively, at a flow rate of 3 mL/min. In this study, in which the profitable sample volume was determined as 400 mL and the amount of multiwalled carbon nanotube (MWCNT) as 50 mg. It was also observed that the column had a significant potential to preconcentrate Zn(II), Ni(II), and Pb(II) even after 25 reuses. The biosorption capacities for Zn(II), Ni(II) and Pb(II) were calculated as 39.67 mg/g, 45.98 mg/g and 51.34 mg/g respectively. The LOD values were calculated as 0.024 ng/mL for Pb(II), 0.029 ng/mL for Ni(II), and 0.019 ng/mL for Zn(II). The linear range was detected as 0.25–25 ng/mL. The concentrations of Pb(II), Ni(II), and Zn(II) in a variety of real food samples were determined by using developed method after application of certified reference sample.

Carbonized MXene-polyvinylpyrrolidone as an adsorbent for solid-phase microextraction of polycyclic aromatic hydrocarbons from tea beverages prior to GC analysis

MXene-polyvinylpyrrolidone (MXene-PVP) was first prepared by physically doping combined with spray drying, which can overcome the aggregation of the MXene. Then, the MXene-PVP was carbonized to result in a carbonized MXene-PVP (MXene-PVP-C), which was then immobilized on stainless steel wire by sol–gel approach to prepare a new solid-phase microextraction (SPME) fiber. The prepared MXene-PVP-C coated fiber was studied for the extraction of 10 polycyclic aromatic hydrocarbons (PAHs) from tea beverages by using SPME method prior to gas chromatographic detection. The main SPME parameters, including extraction temperature, extraction time, salt concentration, sample solution pH and stirring rate, were investigated by central composite design methodology. Under the optimized conditions, the developed method gave the limits of detection of 0.03–0.15 µg/L, and the limits of quantification of 0.10–0.50 µg/L for the PAHs. The method recoveries for the PAHs in spiked tea beverages ranged from 78.6 % to 122 %. The single-fiber and fiber-to-fiber relative standard deviations were lower than 8.2 % and 9.6 %, respectively.

In-tube gel electromembrane extraction: A green strategy for the extraction of narcotic drugs from biological samples

The development of green and miniature extraction methods is always a major and controversial challenge in the field of sample preparation. In this work, in-tube gel electromembrane extraction (IT-G-EME) was developed as a miniaturized extraction device for the extraction of six narcotic drugs (codeine, oxycodone, hydrocodone, tramadol, thebaine, and noscapine) from biological samples. A transparent capillary tube (∼6 cm) was used as a microextraction unit. The middle part of the tube was filled with a narrow plug (∼3 mm) of the agarose gel (3.0% w/v) as a membrane and the other sides were filled with aqueous extractant solution (pH 2.0, 20 µL) and sample solution (pH 5.0, 200 µL). By applying electrical potential (400 V), the target drugs with positive charge were migrated from sample solution toward the extractant solution through gel membrane during short extraction time (5 min). Then, the enriched analytes in extractant solution was analyzed by HPLC-UV. Under the optimized conditions, the calibration curves were linear within the permissible range of 10.0–1500 ng/mL (r2 ≥ 0.991). Limits of detection and extraction recoveries were in the range of 3.0–4.5 ng/mL and 61.9–86.9%, respectively. On the basis of four replications, the repeatability of the method was also evaluated in terms of intra- and inter-day RSDs (%), which did not exceed from 6.6 and 7.9%, respectively in aqueous media. The figures of merit were also assessed in biological samples. Eventually, the developed method was profitably used for simultaneous determination of narcotic drugs in the real urine and plasma samples.

Flower-like mesoporous Fe3O4@SiO2@F/NiO composites for magnetic solid-phase extraction of imidazole fungicides in tap water, milk and green tea

In this work, magnetic flower-like and fluorine-doped nickel oxide composites Fe3O4@SiO2@F/NiO were prepared and applied for the magnetic solid-phase extraction (MSPE) of five imidazole fungicides. The obtained materials were characterized by scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller analysis to verify the successful synthesis. The effect of some experimental parameters on the extraction efficiency were explored to optimize the MSPE conditions, including the adsorbent dosage, ultrasonic time, salt concentration, sample solution pH, elution solvent type and volume. Then, method validation was performed under the optimal conditions in combination with high-performance liquid chromatography-ultraviolet detection. The determination coefficients ranged from 0.9956 to 0.9991, and the limits of detection and limits of quantification for the imidazole fungicides were 0.1–3 μg·L−1 and 0.3–10 μg·L−1, respectively. Moreover, the intra-day and inter-day precisions were evaluated in three different concentrations with relative standard deviations in the range of 1.34 %-13.31 % and 4.96 %-13.92 %. At last, the proposed MSPE method was used to enrich and determine imidazole fungicides in tap water, milk and green tea samples, and the spiked recoveries were in the range of 77.93 %-119.38 %, demonstrating the potential of the method in the determination of imidazole fungicides from real samples.

One-pot synthesis of magnetic sulfonated covalent organic polymer for extraction of protoberberine alkaloids in herbs and human plasma.

A novel magnetic sulfonated covalent organic polymer was prepared for magnetic solid-phase extraction of protoberberine alkaloids. The magnetic sulfonated covalent organic polymer was rapidly synthesized under mild conditions. The physicochemical properties of the prepared materials were characterized by Fourier-transform infrared spectrometry, transmission electron microscopy, and X-ray photoelectron spectroscopy. Several extraction parameters were systematically investigated, including desorption time, pH of sample solution, acetonitrile content, acetic acid content in the eluent, extraction time, and sample volume. By coupling magnetic solid-phase extraction and high-performance liquid chromatography, an efficient and sensitive method for the extraction and determination of protoberberine alkaloids in complex samples was developed. The proposed method showed great linearity (r>0.9989), low limits of detection (0.2-0.3ng/ml), and high precision (relative standard deviations ≤ 5.74%). The proposed method was further applied to the analysis of protoberberine alkaloids in Cortex phellodendri and human plasma samples. The recoveries were 91.50%-110.31% with relative standard deviations less than 6.63% in Cortex phellodendri and 96.12%-111.20% with relative standard deviations lower than 5.56% in plasma samples.

Preparation of an efficient magnetic nano-sorbent based on modified cellulose and carboxylated carbon nano-tubes for extraction of pesticides from food and agricultural water samples before GC-FID analysis

This paper reports the direct synthesis approach of carboxamide functionalized magnetic nano-composite named Fe3O4@SiO2-NH2@dialdehyde cellulose (DAC)@CNT-COOH as an effectual sorbent for the co-extraction of seven agricultural insecticides and herbicides from vegetable, fruit, and water samples using the magnetic dispersive micro-solid-phase extraction procedure. Under the optimized extraction conditions (sorbent amount: 18.1 mg; desorption time: 6.5 min; desorption solvent volume: 185 μL; desorption solvent: acetonitrile; extraction time: 9.5 min; pH of sample solution: 7.0, and salt content: 5.0 % w/v sodium chloride), good linearity within the range 0.5–1200 ng/mL (R2 ≥ 0.998) was achieved. Extraction efficiencies were in the range 63.4–84.1 %, the limits of detection were 0.08–1.0 ng/mL, and acceptable relative recoveries (87.6–103.8 %), and precisions were also achieved (RSDs < 6.8 %, n = 3). Ultimately, the obtained results showed that the developed method could be applied to determine trace amounts of desired analytes in various agricultural water and food samples.

Deep eutectic solvent - loaded Fe3O4@MIL-101(Cr) with core–shell structure for the magnetic solid phase extraction of non-steroidal anti-inflammatory drugs in environmental water samples

A novel deep eutectic solvent - loaded magnetic solid phase extraction (DES-L-MSPE) method was proposed, which was based on the direct loading of a hydrophobic DES composed of L-menthol and lactic acid (1:2) into the pores of core–shell magnetic Fe3O4@MIL-101(Cr) nanoparticles. The function of DES was to condition the Fe3O4@MIL-101(Cr) and promote liquid phase microextraction for the analytes. Through coupling with HPLC-UV analysis, this method was utilized for the determination of six non-steroidal anti-inflammatory drugs (NSAIDs), including ketoprofen, naproxen, flurbiprofen, diclofenac sodium, ibuprofen, and mefenamic acid in environmental water samples. The influencing parameters such as type and ratio of DES, amount of adsorbent, sample solution pH, salt concentration, extraction time, elution solvent and time were investigated and optimized in detail. Under the optimal conditions, the method exhibited good linearity (5.0–1000 μg/L for ketoprofen, ibuprofen, 1.5–600 μg/L for flurbiprofen, mefenamic acid, 2.5–1000 μg/L for naproxen and 3.0–600 μg/L for diclofenac sodium with the correlation coefficients ranging from 0.9972 to 0.9993), low limits of detection (0.20–1.1 μg/L), and high precision (RSD < 8.2 %). Besides, the recoveries in spiked lake and river water samples were 89.8 %–110.4 % and 83.8 %–109.0 %, respectively. Taken together, the established method was proved to be simple, fast, highly sensitive and accurate for the determination of NSAIDs from aqueous matrices.

Design, structural, spectral, DFT and analytical studies of novel nano-palladium schiff base complex

A novel nano-palladium (II) Schiff base complex (C1) is synthesized by the reaction between palladium chloride and the Schiff base N, N’-1, 2-phenylene) bis (3 -aminobenzamide (A1). The prepared compounds were characterized by elemental analysis, Ultraviolet–Visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Thermogravimetric Analysis (TGA). A combined solvent sublation-ICP OES methodology has been studied for the preconcentration, separation and determination of trace palladium (II) in media of diverse origin using the Schiff base ligand (A1). The different experimental variables that affect the sublation efficiency (S, %) were thoroughly investigated viz.: pH of sample solution; amounts of A1, Pd (II) and TBAB; type and amounts of surfactants, types of organic solvent, temperature and stirring time. The method involves the determination of trace palladium (II) after selective separation by solvent sublation, thus eliminating the effect of foreign ions and increasing the sensitivity. Also, palladium is determined directly in the organic phase, which decreases the determination time and its loss during determination. At optimum conditions, the linear range of Pd (II) was 10.0–100.0 ngmL−1. The coefficient of determination, the limit of detection (LOD) and limit of quantification (LOQ) were 0.9943, 21.29 ngL−1 and 64.5 ngL−1, respectively. This sublation method was applied to real samples and recoveries of more than 95% were obtained in the spiked samples with a preconcentration factor of 100. The mechanism of solvent sublatation of the TBA.[PdII-(A1)2] ion pairs is discussed. The computational studying was estimated to approve the geometry of the isolated solid compounds.

Application of levulinic acid-based natural deep eutectic solvents for extraction and determination of deltamethrin in food samples

In the study, a fast and green natural deep eutectic solvent based ultrasound-assisted liquid liquid microextraction (NDES-UALLME) were proposed for the determination and extraction of deltamethrin in food samples using UV/Vis spectrophotometry. The extraction step was based on ion-pair formation between deltamethrin and levulinic acid-tetraethylammonium bromide (as extraction solvent) at pH 5.5, and then extraction of deltamethrin into micro-drops of extraction solvent by using tetrahydrofuran. Levulinic acid-based natural deep eutectic solvents composed of natural, green compounds, i.e., choline acetyl chloride, tetrabutylammonium bromide, tetraethylammonium chloride and tetraethylammonium bromide were used for the first time as extraction solvents for extraction of deltamethrin. The NDES-UALLME procedure allowed to exclude matrixes effects and increase enrichment factor (283) of deltamethrin. Several key factors, including the type and the volume of extraction solvent, the pH of sample solution, ultrasound time, extraction temperature, ionic strength and sample volume were optimized in detail. At optimized conditions, the NDES-UALLME procedure was characterized by low limit of detection (2.4 ng mL−1), a wide linear dynamic range (8–950 ng mL−1), quantitative recoveries (93 ± 4%-103 ± 2%) and acceptable relative standard deviations (2.9%≤). The validation of NDES-UALLME procedure was carried out using recovery tests, intraday and intraday studies. The applicability of NDES-UALLME procedure was confirmed by the assay of deltamethrin in real food samples.

Three-dimensional flower-like SnS2 materials for dispersive solid-phase extraction of endocrine-disrupting phenols.

In this study, three-dimensional flower-like tin disulfide materials were prepared, and a highly efficient dispersive solid-phase extraction method was developed using the obtained three-dimensional tin disulfide adsorbents for the preconcentration and determination of six endocrine-disrupting phenols in combination with high-performance liquid chromatography-ultraviolet detection. Several important experimental parameters influencing extraction efficiency were investigated, including the amount of adsorbent, ultrasound time, sample solution pH, sample volume, type of elution solvent, desorption time, and the number of desorption times. Under the optimized experimental conditions, the developed method showed good linearity with the determination coefficients of 0.993-0.998 in the linear range of 0.5-400ng/ml and low limits of detection in the range of 0.15-1.0ng/ml, as well as satisfactory intra-day and inter-day precisions with relative standard deviations of 0.1-9.8%. Finally, the proposed method was successfully applied for the enrichment and determination of trace endocrine-disrupting phenols in milk, tea beverage, and plastic bottled water samples, and acceptable recoveries were obtained from 70.1% to 119.1% under four different spiked concentration levels. The results showed that the three-dimensional tin disulfide materials had great potential for the extraction of endocrine-disrupting phenols contaminants in environmental and food samples.

Dispersive solid-phase extraction for determination of fast green and erythrosine dyes in environmental water samples using Zein bio-nanoparticles

ABSTRACT Colour additives are commonly used in the food industry to improve product appearance and nutritional characteristics. However, effluent containing reactive dyes from food and textile dyeing industries is a substantial cause of pollution in the environment. Simple and ecofriendly trace analysis of two synthetic food azo dyes including fast green (FG) and erythrosine (ER) dyes from environmental water samples was developed by combining dispersive μ-solid-phase extraction with UV-Vis spectrophotometric detection. Zein biopolymeric nanoparticles (ZNPs) were used as a green sorbent for preconcentration of trace amounts of the mentioned food dyes. Based on the anti-solvent method, the ethanolic Zein solution (20 mg) was injected rapidly into the sample, and the ZNPs were produced. After centrifugation, the adsorbed dye was separated, and samples were analysed using a spectrophotometric technique. The impact of various extraction parameters, such as extraction time, adsorbent amount, surfactant type and concentration, ionic strength, pH of sample solution, and desorption conditions, was examined. Under optimised conditions, the linearity ranges were 0.005–1.2 and 0.01–2 µg mL−1 with correlation coefficient (r2) of 0.9970 and 0.9972 for FG and ER respectively. The method has good reproducibility, with relative standard deviations of less than 4.2% (n = 5) and detection limits of 2.5 and 6 ng mL−1 for both dyes respectively. The current approach was used to analyse three environmental water samples (river, canal, and well water), and the dyes recoveries were 94.0–102.6% and 95.7–101.7% for FG and ER respectively. The findings revealed that the proposed approach was convenient, fast, and effective.

MIL-88B(Fe)/cellulose microspheres as sorbent for the fully automated dispersive pipette extraction towards trace sulfonamides in milk samples prior to UPLC-MS/MS analysis

MIL-88B(Fe)/cellulose microspheres (MIL-88B(Fe)/CMs) were characterized by the means of SEM, XRD, TGA and N2 adsorption-desorption test. The composite was used as the sorbent for fully automated dispersive pipette extraction (DPX), after introducing CMs as the support, the loss of MIL-88B(Fe) in DPX was avoided. Coupled to UPLC-MS/MS, the proposed method was employed for the analysis of trace sulfonamides (SAs) in milk samples. The parameters affecting the extraction efficiency, including pH of sample solution, the rate of aspiration and dispense, amount of the adsorbent, type and volume of elution solvent were optimized. Under the optimal conditions, good linearity (r ≥ 0.9978 for five analytes), high sensitivity (limit of detection: 0.00660–0.0136 μg kg−1) and satisfactory recovery (69.8%–100.9%) were achieved. Furthermore, the sorbent showed desirable reusability over eight extraction cycles. Compared with other methods for the pretreatment of SAs, the proposed method showed advantages of high sensitivity, less sorbent consumption, environmental friendliness and automation, providing a promising protocol for sample preparation.

Corona discharge ionization ion mobility spectrometry for ultra-trace determination of methamphetamine extracted from urine and plasma samples by dispersive liquid–liquid microextraction

In this work, dispersive liquid-liquid microextraction (DLLME) based on high-density extraction solvent was applied as a simple, fast and sensitive method for extraction and preconcentration of methamphetamine from human plasma and urine samples. The efficiency of positive corona discharge ionization ion mobility spectrometry was investigated for direct analysis of the extracted analyte. Effective parameters on the extraction efficiency, such as type and volume of the extraction and disperser solvents, centrifugation time, and sample solution pH were optimized. Trichloromethane and isopropanol were selected as the extracting and disperser solvents, respectively. Under the optimized conditions, the linear dynamic range (R2 = 0.9969) was found to be 0.5-18µg/L, and 0.15µg/L was calculated as the limit of detection. The relative standard deviations of intra- and inter-day were obtained 4 and 10%, respectively, and finally, in the analysis of human plasma and urine samples, the extraction recovery was obtained 104%.

Novel core–shell SiO2@dSiO2@NH2-MIL-53(Al) packed into solid phase extraction column for enrichment of non-steroidal anti-inflammatory drugs prior to UPLC-MS/MS

NH2-MIL-53(Al) was in situ synthesized on the SiO2@dSiO2 with a simple solvothermal method. The prepared composite was packed into column solid phase extraction as adsorbent. After introduction of SiO2@dSiO2 as the support, the drawbacks of adsorbent loss and high backpressure were overcome. Using ultra-high performance liquid chromatography-mass spectrometry, the proposed method was employed to analyze trace non-steroidal anti-inflammatory drugs (NSAIDs) in water samples. Extraction parameters, including type of adsorbent, pH of sample solution, flow rate, sample volume, type and volume of elution solvent, were optimized. Then commendable sensitivity was obtained with limits of detection from 0.5 to 4.0 pg·mL−1, and limits of quantification from 1.5 to 13.3 pg·mL−1. Moreover, the correlation coefficient (r) of linearity was 0.9916–0.9974. Satisfactorily, the recoveries of the target compounds were between 75.3 % and 109.3 %, and the relative standard deviation was less than 7.8 %. Furthermore, naproxen was chosen as a nominee to evaluate adsorption behavior of SiO2@dSiO2@NH2-MIL-53(Al). Molecular docking simulation calculations were conducted to explore adsorption mechanism between NH2-MIL-53(Al) and five NSAIDs.

Application of nanostructured supramolecular solvent based on C12mimBr ionic liquid surfactant to direct extraction of some chlorophenols in soil and rice samples

In the proposed research, ionic liquid surfactant (C12-mimBr)-based nanostructured supramolecular solvent (IL-SUPRAS) was applied for direct extraction and preconcentration of three chlorophenols (CPs) in soil and rice samples before using gas chromatography-flame ionization detection (GC-FID) analysis. Mainly for extraction of analyte from a solid sample, an initial extraction step is performed using harmful organic solvents. Then, after evaporation of those solvents, the secondary extraction method is applied. The purpose of this research is direct extraction of some analytes from solid samples without performing the initial extraction step and using an adverse organic solvent. At first, IL-SUPRAS aggregation was prepared in a water solution. After that, an appropriate amount of it was introduced to the Eppendorf vial containing the solid sample. In the next step, to effectively extract the analytes from samples to the SUPRAS phase, the Eppendorf vial was vortexed and centrifuged, respectively. Finally, to prevent the entrance of the SUPRAS phase into the GC instrument, a back extraction step of the analytes was performed. The influence of effective parameters (i.e., pH of sample solution, vortex time, centrifuge time, and volume of THF) on the extraction procedure was investigated. Under optimum experimental conditions, the enrichment factors were obtained in the reasonable range of 103.2–134.6. The calibration curves also were linear in the range of 1.0–2000 µg L-1 with coefficients of determination (R2) more than 0.9962 for all three analytes. Limits of detection (S/N = 3) of 0.3–0.7 µg L-1, thelimits of quantification (LOQ) of 0.99–2.1 µg L-1, the relative standard deviations (RSDs %) composed of inter-day RSD (7.6–8.7) and intra-day RSD (6.3–7.6),and relative recoveries in the range of 77.4–93.6 % were obtained. The proposed method (IL-SUPRAS-DME) was successfully applied, for direct and fast extraction of CPs analytes in soil and rice samples.

Preparation of novel bifunctionalized magnetic nanoparticles for sequential speciation analysis of inorganic arsenic

An amino- and mercapto-bifunctionalized magnetic nanocomposite (SMNPs-(NH2 + SH)) was synthesized by modification of silica-coated magnetic nanoparticles (SMNPs) via one-pot co-condensation of 3-aminopropyltriethoxysilane (APTES) and 3-mercaptopropyltrimethoxysilane (MPTMS) for the first time. The bifunctional magnetic nanomaterial was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry, X-ray photoelectric spectroscopy, elemental analysis, thermogravimetric analysis and vibrating sample magnetometry, etc. The prepared SMNPs-(NH2 + SH) nanocomposite was employed as magnetic solid-phase extraction (MSPE) sorbent for speciation of inorganic arsenic without any pre-oxidation or pre-reduction process. Different optimal conditions for the MSPE including sample solution pH and volume, adsorbent amount, loading time, eluent composition and volume, and elution time were investigated systematically. As(V) and As(III) were adsorbed simultaneously at pH 4.0, and then desorbed sequentially by 3 % (v/v) HNO3 and 3 % (v/v) HNO3 with 4 % (m/v) mercaptosuccinic acid followed by inductively coupled plasma-mass spectrometry (ICP-MS) analysis with the limits of detection of 15.2 and 24.5 ng/L respectively at an enrichment factor of 10 fold. The reliability of the stepwise speciation strategy based on SMNPs-(NH2 + SH) was validated by analyzing inorganic arsenic species in certified reference material of environmental water as well as mixed standard solutions of As(V) and As(III), and the results were in good accordance with the certified or standard values. The applicability of the SMNPs-(NH2 + SH)-MSPE-ICP-MS method for speciation analysis of inorganic arsenic was evaluated in spiked tap, rain, lake and river water samples at the recoveries of 92 %–102 % and 92 %–100 % with the relative standard deviations of 3.6 %–7.4 % and 2.3 %–8.2 % for As(V) and As(III) respectively. In consideration of the merits of single adsorbent, facile preparation, easy operation and no invasion to labile inorganic arsenic, the bifunctional material based MSPE protocol is attractive for speciation analysis of arsenic in real environmental samples.

Potential of sodium dodecyl sulfate micellar solutions as eluents in magnetic dispersive micro-solid phase extraction with polydopamine-coated magnetite nanoparticles. Application to antidepressant drugs

In this paper, the potential of micellar solutions of the anionic surfactant sodium dodecyl sulfate (SDS) as eluents in dispersive micro-solid phase extraction (D-μSPE) using polydopamine-coated magnetite nanoparticles (Fe3O4@PDA NPs) for the extraction and preconcentration of seven basic drugs (bupropion, citalopram, fluoxetine, mianserin, nomifensine, trimipramine, and viloxazine) is explored for the first time (to the best to our knowledge) and compared with conventional hydro-organic eluents. The impact of the sample solution pH, Fe3O4@PDA NPs and PDA coating amounts and extraction time on the extraction efficiency (EE), as well as the composition of the eluent on the overall efficiency (OE) are studied. Under the selected experimental conditions (50 mg of Fe3O4@PDA NPs, 100 μL of 1 M NH3, 5 min of extraction time and 0.15 M SDS at pH 2.6 as eluent), EE and OE values were higher than 90% for all compounds and for the most hydrophobic compounds (trimipramine, fluoxetine and mianserin), respectively. The results shown in this paper demonstrate the suitability of Fe3O4@PDA NPs as a sorbent for the extraction of antidepressants as well as the advantages of using SDS micellar solutions over classic hydro-organic eluents containing methanol, acetonitrile or tetrahydrofuran. Finally, the stability and reusability of the Fe3O4@PDA NPs is proven.