Efficient synthesis of molecularly imprinted polymers with bio-recognition sites for the selective separation of bovine hemoglobin

We developed a facile approach to the construction of bio-recognition sites in silica nanoparticles for efficient separation of bovine hemoglobin based on amino-functionalized silica nanoparticles grafting by 3-aminopropyltriethoxylsilane providing hydrogen bonds with bovine hemoglobin through surface molecularly imprinting technology. The resulting amino-functionalized silica surface molecularly imprinted polymers were characterized using scanning electron microscope, transmission electronic microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis. Results showed that the as-synthesized imprinted polymers exhibited spherical morphology and favorable thermal stability. The binding adsorption experiments showed that the imprinted polymers can reach equilibrium within 1 h. The Langmuir isotherm and pseudo-second-order kinetic model fitted the adsorption data well. Meanwhile, the maximum binding capacity was up to 90.3 mg/g and highly selectivity for the recognition of bovine hemoglobin. Moreover, such high binding capacity and selectivity retained after eight cycles, indicating the good stability and reusability of the imprinted polymers. Finally, successful application in the selective recognition of bovine hemoglobin from a real bovine blood sample indicated that the imprinted polymers displayed great potentials in efficient purification and separation of target proteins.
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Abstract

We developed a facile approach to the construction of bio-recognition sites in silica nanoparticles for efficient separation of bovine hemoglobin based on amino-functionalized silica nanoparticles grafting by 3-aminopropyltriethoxylsilane providing hydrogen bonds with bovine hemoglobin through surface molecularly imprinting technology. The resulting amino-functionalized silica surface molecularly imprinted polymers were characterized using scanning electron microscope, transmission electronic microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis. Results showed that the as-synthesized imprinted polymers exhibited spherical morphology and favorable thermal stability. The binding adsorption experiments showed that the imprinted polymers can reach equilibrium within 1 h. The Langmuir isotherm and pseudo-second-order kinetic model fitted the adsorption data well. Meanwhile, the maximum binding capacity was up to 90.3 mg/g and highly selectivity for the recognition of bovine hemoglobin. Moreover, such high binding capacity and selectivity retained after eight cycles, indicating the good stability and reusability of the imprinted polymers. Finally, successful application in the selective recognition of bovine hemoglobin from a real bovine blood sample indicated that the imprinted polymers displayed great potentials in efficient purification and separation of target proteins.

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Preparation of bio-based keratin-derived magnetic molecularly imprinted polymer nanoparticles for the facile and selective separation of bisphenol A from water

In this study, new bio-based magnetic molecularly imprinted polymer nanoparticles (∼23 nm) were synthesized from keratin extracted from chicken feathers and methacrylate-functionalized Fe3O4 nanoparticles for its potential application in separation and removal of bisphenol A from water. The prepared magnetic molecularly imprinted polymer was characterized by Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, thermogravimetric analysis, alternative gradient field magnetometry, and energy-dispersive X-ray spectroscopy. The sorption of bisphenol A was investigated by changing the influencing factors such as pH, immersion time, Fe3O4 nanoparticles dosage, and the initial concentration of bisphenol A. Results illustrated that sorption was very fast and efficient (Qm = 600 mg g−1) having a removal efficiency of ∼98 % in 40 min of immersion. The adsorption process showed better conformity with the Weber−Morris kinetics and the Freundlich isotherm model. The selectivity of bisphenol A by adsorbent was checked in the presence of hydroquinone, phenol, tetrabromobisphenol, and 4,4′-biphenol as interferences.
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Abstract

In this study, new bio-based magnetic molecularly imprinted polymer nanoparticles (∼23 nm) were synthesized from keratin extracted from chicken feathers and methacrylate-functionalized Fe3O4 nanoparticles for its potential application in separation and removal of bisphenol A from water. The prepared magnetic molecularly imprinted polymer was characterized by Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, thermogravimetric analysis, alternative gradient field magnetometry, and energy-dispersive X-ray spectroscopy. The sorption of bisphenol A was investigated by changing the influencing factors such as pH, immersion time, Fe3O4 nanoparticles dosage, and the initial concentration of bisphenol A. Results illustrated that sorption was very fast and efficient (Q= 600 mg g−1) having a removal efficiency of ∼98 % in 40 min of immersion. The adsorption process showed better conformity with the Weber−Morris kinetics and the Freundlich isotherm model. The selectivity of bisphenol A by adsorbent was checked in the presence of hydroquinone, phenol, tetrabromobisphenol, and 4,4′-biphenol as interferences.

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Analysis of new psychoactive substances in human urine by ultra high performance supercritical fluid and liquid chromatography: Validation and comparison

New psychoactive substances represent serious social and health problem as tens of new compounds are detected in Europe annually. They often show structural proximity or even isomerism which complicates their analysis. Two methods based on ultra high performance supercritical fluid chromatography and ultra high performance liquid chromatography with mass spectrometric detection were validated and compared. A simple dilute-filter-and-shoot protocol utilizing propan-2-ol or methanol for supercritical fluid or liquid chromatography, respectively, was proposed to detect and quantify 15 cathinones and phenethylamines in human urine. Both methods offered fast separation (<3 min) and short total analysis time. Precision was well below 15% with a few exceptions in liquid chromatography. Limits of detection in urine ranged from 0.01 to 2.3 ng/mL, except for cathinone (5 ng/mL) in supercritical fluid chromatography. Nevertheless, this technique distinguished all analytes including four pairs of isomers, while liquid chromatography was unable to resolve fluoromethcathinone regioisomers. Concerning matrix effects and recoveries, supercritical fluid chromatography produced more uniform results for different compounds and at different concentration levels. This work demonstrates the performance and reliability of supercritical fluid chromatography and corroborates its applicability as an alternative tool for analysis of new psychoactive substances in biological matrixes.
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Abstract

New psychoactive substances represent serious social and health problem as tens of new compounds are detected in Europe annually. They often show structural proximity or even isomerism which complicates their analysis. Two methods based on ultra high performance supercritical fluid chromatography and ultra high performance liquid chromatography with mass spectrometric detection were validated and compared. A simple dilute-filter-and-shoot protocol utilizing propan-2-ol or methanol for supercritical fluid or liquid chromatography, respectively, was proposed to detect and quantify 15 cathinones and phenethylamines in human urine. Both methods offered fast separation (<3 min) and short total analysis time. Precision was well below 15% with a few exceptions in liquid chromatography. Limits of detection in urine ranged from 0.01 to 2.3 ng/mL, except for cathinone (5 ng/mL) in supercritical fluid chromatography. Nevertheless, this technique distinguished all analytes including four pairs of isomers, while liquid chromatography was unable to resolve fluoromethcathinone regioisomers. Concerning matrix effects and recoveries, supercritical fluid chromatography produced more uniform results for different compounds and at different concentration levels. This work demonstrates the performance and reliability of supercritical fluid chromatography and corroborates its applicability as an alternative tool for analysis of new psychoactive substances in biological matrixes.

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Amino acid racemization and its relation to geochronology and archaeometry

Amino acid racemization, used as a method of relative and quantitative dating of fossils, evaluates the degree of postmortem conversion of l to d amino acid enantiomers. While extensively utilized, this method has garnered confusion due to controversial age estimates for human fossils in North America in the 1970s. This paper explains the age controversy and aftermath, current chromatographic methods used in research, mathematical calibration models, and a short synopsis of other dating techniques in geochronology and archaeometry.
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Abstract

Amino acid racemization, used as a method of relative and quantitative dating of fossils, evaluates the degree of postmortem conversion of l to d amino acid enantiomers. While extensively utilized, this method has garnered confusion due to controversial age estimates for human fossils in North America in the 1970s. This paper explains the age controversy and aftermath, current chromatographic methods used in research, mathematical calibration models, and a short synopsis of other dating techniques in geochronology and archaeometry.

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Simple method for the determination of personal care product ingredients in lettuce by ultrasound-assisted extraction combined with solid-phase microextraction followed by GC–MS

A simple method for the simultaneous determination of personal care product ingredients: galaxolide, tonalide, oxybenzone, 4-methylbenzyliden camphor, padimate-o, 2-ethylhexyl methoxycinnamate, octocrylene, triclosan and methyl triclosan in lettuce by ultrasound-assisted extraction combined with solid-phase microextraction followed by gas chromatography with mass spectrometry was developed. Lettuce was directly extracted by ultrasound-assisted extraction with methanol, this extract was combined with water, extracted by solid-phase microextraction in immersion mode and analyzed by gas chromatography with mass spectrometry. Good linear relationships (25–250 ng g−1, R2 > 0.9702) and low detection limits (1.0–25 ng g−1) were obtained for analytes along with acceptable precision for almost all analytes (RSDs < 20%). The validated method was applied for the determination of personal care product ingredients in commercial lettuce and lettuces grown in soil and irrigated with the analytes, identifying the target analytes in leaves and roots of the latter. This procedure is a miniaturized and environmentally friendly proposal which can be a useful tool for quality analysis in lettuce.
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Abstract

A simple method for the simultaneous determination of personal care product ingredients: galaxolide, tonalide, oxybenzone, 4-methylbenzyliden camphor, padimate-o, 2-ethylhexyl methoxycinnamate, octocrylene, triclosan and methyl triclosan in lettuce by ultrasound-assisted extraction combined with solid-phase microextraction followed by gas chromatography with mass spectrometry was developed. Lettuce was directly extracted by ultrasound-assisted extraction with methanol, this extract was combined with water, extracted by solid-phase microextraction in immersion mode and analyzed by gas chromatography with mass spectrometry. Good linear relationships (25–250 ng g−1, R> 0.9702) and low detection limits (1.0–25 ng g−1) were obtained for analytes along with acceptable precision for almost all analytes (RSDs < 20%). The validated method was applied for the determination of personal care product ingredients in commercial lettuce and lettuces grown in soil and irrigated with the analytes, identifying the target analytes in leaves and roots of the latter. This procedure is a miniaturized and environmentally friendly proposal which can be a useful tool for quality analysis in lettuce.

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Effect of the flow profile on separation efficiency in pressure-assisted reversed-polarity capillary zone electrophoresis of anions: Simulation and experimental evaluation

Capillary electrophoresis connected to electrospray ionization mass spectrometry is a promising combination to analyze complex biological samples. The use of sheathless electrospray ionization interfaces, such as a porous nanoelectrospray capillary emitter, requires the application of forward flow (either by pressure or electroosmosis) to maintain the electrospray process. The analysis of solute molecules with strong negative charges (e.g., aminopyrenetrisulfonate labeled glycans) necessitates a reversed-polarity capillary electrophoresis separation mode, in which case the electroosmotic flow is counter current, thus pressure assistance is necessary. In this study, we compared the effect of forced convection with and without counter electroosmotic flow on the resulting separation efficiency in capillary electrophoresis based on flow profile simulations by computational fluid dynamics technique and by actual experiments. The efficiencies of the detected peaks were calculated from the resulting electropherograms and found approximately 790 000 plates/m for electrophoresis with counter electroosmotic flow, 16 000 plates/m with pressure only (such as would be in open tubular liquid chromatography) and 400 000 plates/m for electrophoresis with simultaneous counter electroosmotic flow and forward pressure assistance, which validates the simulation data.
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Abstract

Capillary electrophoresis connected to electrospray ionization mass spectrometry is a promising combination to analyze complex biological samples. The use of sheathless electrospray ionization interfaces, such as a porous nanoelectrospray capillary emitter, requires the application of forward flow (either by pressure or electroosmosis) to maintain the electrospray process. The analysis of solute molecules with strong negative charges (e.g., aminopyrenetrisulfonate labeled glycans) necessitates a reversed-polarity capillary electrophoresis separation mode, in which case the electroosmotic flow is counter current, thus pressure assistance is necessary. In this study, we compared the effect of forced convection with and without counter electroosmotic flow on the resulting separation efficiency in capillary electrophoresis based on flow profile simulations by computational fluid dynamics technique and by actual experiments. The efficiencies of the detected peaks were calculated from the resulting electropherograms and found approximately 790 000 plates/m for electrophoresis with counter electroosmotic flow, 16 000 plates/m with pressure only (such as would be in open tubular liquid chromatography) and 400 000 plates/m for electrophoresis with simultaneous counter electroosmotic flow and forward pressure assistance, which validates the simulation data.

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Application of off-line two-dimensional high-performance countercurrent chromatography on the chloroform-soluble extract of Cuscuta auralis seeds

In this study, the chloroform-soluble extract of C. auralis was separated successfully using off-line two-dimensional high-performance countercurrent chromatography, yielding a γ-pyrone, two alkaloids, a flavonoid and four lignans. The first-dimensional countercurrent separation using a methylene chloride/methanol/water (11:6:5, v/v/v) system yielded three sub-fractions (fractions I–III). The second-dimensional countercurrent separations, conducted on fractions I–III using n-hexane/ethyl and acetate/methanol/acetic acid (5:5:5:5:0, 3:7:3:7:0 and 1:9:1:9:0.01, v/v/v/v/v) systems, gave maltol (1), (−)-(13S)-cuscutamine (2), (+)-(13R)-cuscutamine (3), (+)-pinoresinol (4), (+)-epipinoresinol (5), kaempferol (6), piperitol (7) and (9R)-hydroxy-d-sesamin (8). To the best of our knowledge, maltol was identified for the first time in Cuscuta species. Furthermore, this report details the first full assignment of spectroscopic data of two cuscutamine epimers, (−)-(13S)-cuscutamine and (+)-(13R)-cuscutamine.
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Abstract

In this study, the chloroform-soluble extract of C. auralis was separated successfully using off-line two-dimensional high-performance countercurrent chromatography, yielding a γ-pyrone, two alkaloids, a flavonoid and four lignans. The first-dimensional countercurrent separation using a methylene chloride/methanol/water (11:6:5, v/v/v) system yielded three sub-fractions (fractions I–III). The second-dimensional countercurrent separations, conducted on fractions I–III using n-hexane/ethyl and acetate/methanol/acetic acid (5:5:5:5:0, 3:7:3:7:0 and 1:9:1:9:0.01, v/v/v/v/v) systems, gave maltol (1), (−)-(13S)-cuscutamine (2), (+)-(13R)-cuscutamine (3), (+)-pinoresinol (4), (+)-epipinoresinol (5), kaempferol (6), piperitol (7) and (9R)-hydroxy-d-sesamin (8). To the best of our knowledge, maltol was identified for the first time in Cuscuta species. Furthermore, this report details the first full assignment of spectroscopic data of two cuscutamine epimers, (−)-(13S)-cuscutamine and (+)-(13R)-cuscutamine.

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Elution–extrusion counter-current chromatography separation of six pairs of isomeric iridoids from Cornus officinalis Sieb. et Zucc. guided by ion current extraction in mass spectrometry

A mass spectrometry guided elution–extrusion counter-current chromatography protocol was developed to separate chemical components from Cornus officinalis Sieb. et Zucc. Ion current extraction, a mass spectrometry based data post-acquisition method, was utilized to boost the separation power and scope of counter-current chromatography technique in this study. As a peak re-picking and denoising tool, ion current extraction was carried out to process the liquid chromatography with mass spectrometry and the counter-current chromatography with mass spectrometry data. So the target components were re-acquired in the created extracted ion current patterns with enhanced responses and diminished background noise, which facilitated the distribution constant determination (by liquid chromatography with extracted ion current) and the targets fractionation (by counter-current chromatography with extracted ion current). Under the guidance of the extracted ion currents of the target components and with the support of elution–extrusion mode in the counter-current chromatography separation, six pairs of minor iridoid isomers were obtained in shortened experimental duration. Besides, a reciprocal shifted symmetry plot was established to represent the elution–extrusion counter-current chromatography chromatogram. The results demonstrated the capability of the ion current extraction guided elution–extrusion counter-current chromatography protocol in discovery, analysis, and fractionation of low-concentration and structurally similar chemicals from a complicated sample.
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Abstract

A mass spectrometry guided elution–extrusion counter-current chromatography protocol was developed to separate chemical components from Cornus officinalis Sieb. et Zucc. Ion current extraction, a mass spectrometry based data post-acquisition method, was utilized to boost the separation power and scope of counter-current chromatography technique in this study. As a peak re-picking and denoising tool, ion current extraction was carried out to process the liquid chromatography with mass spectrometry and the counter-current chromatography with mass spectrometry data. So the target components were re-acquired in the created extracted ion current patterns with enhanced responses and diminished background noise, which facilitated the distribution constant determination (by liquid chromatography with extracted ion current) and the targets fractionation (by counter-current chromatography with extracted ion current). Under the guidance of the extracted ion currents of the target components and with the support of elution–extrusion mode in the counter-current chromatography separation, six pairs of minor iridoid isomers were obtained in shortened experimental duration. Besides, a reciprocal shifted symmetry plot was established to represent the elution–extrusion counter-current chromatography chromatogram. The results demonstrated the capability of the ion current extraction guided elution–extrusion counter-current chromatography protocol in discovery, analysis, and fractionation of low-concentration and structurally similar chemicals from a complicated sample.

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Evaluation of solid-phase extraction procedures for the quantitation of venlafaxine in human saliva by HPLC

In recent years, the use of human saliva for diagnostic purposes has evoked great interest. Thus, the aim of this study was to choose the optimal solid-phase extraction cartridges and extraction solvents for the quantitation of venlafaxine in saliva. Blank saliva samples spiked with venlafaxine concentrations between 25 and 750 ng/mL were analyzed using five solid-phase extraction columns (C18, C8, Strata-X, Strata-X-C, and Strata-X-AW), washing solvents (deionized water, phosphate buffer at pH 5.5, and their mixtures with methanol) and elution solvents (methanol, acetonitrile, and their mixtures with 25% ammonia). A high-performance liquid chromatography system was used to quantify venlafaxine in saliva. The results of this study revealed that 9 out of 25 procedures enabled quantitation of venlafaxine in the tested concentration range. The procedure that used a C18 cartridge, a mixture of methanol and deionized water as the washing solvent and methanol as the elution solvent was the most effective and allowed quantitation of all venlafaxine concentrations with an acceptable recovery. In contrast, the Strata-X-C cartridge could not detect venlafaxine at the lowest concentration (25 ng/mL). The data acquired from the HPLC system were confirmed by a multivariate data analysis.
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Abstract

In recent years, the use of human saliva for diagnostic purposes has evoked great interest. Thus, the aim of this study was to choose the optimal solid-phase extraction cartridges and extraction solvents for the quantitation of venlafaxine in saliva. Blank saliva samples spiked with venlafaxine concentrations between 25 and 750 ng/mL were analyzed using five solid-phase extraction columns (C18, C8, Strata-X, Strata-X-C, and Strata-X-AW), washing solvents (deionized water, phosphate buffer at pH 5.5, and their mixtures with methanol) and elution solvents (methanol, acetonitrile, and their mixtures with 25% ammonia). A high-performance liquid chromatography system was used to quantify venlafaxine in saliva. The results of this study revealed that 9 out of 25 procedures enabled quantitation of venlafaxine in the tested concentration range. The procedure that used a C18 cartridge, a mixture of methanol and deionized water as the washing solvent and methanol as the elution solvent was the most effective and allowed quantitation of all venlafaxine concentrations with an acceptable recovery. In contrast, the Strata-X-C cartridge could not detect venlafaxine at the lowest concentration (25 ng/mL). The data acquired from the HPLC system were confirmed by a multivariate data analysis.

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A novel sorbent based on carbon nanotube/amino-functionalized sol–gel for the headspace solid-phase microextraction of α-bisabolol from medicinal plant samples using experimental design

A novel sol–gel coating on a stainless-steel fiber was developed for the first time for the headspace solid-phase microextraction and determination of α-bisabolol with gas chromatography and flame ionization detection. The parameters influencing the efficiency of solid-phase microextraction process, such as extraction time and temperature, pH and ionic strength were optimized by experimental design method. Under optimized conditions, the linear range was between 0.0027 and 100 μg/mL. The relative standard deviations determined at 0.01 and 1.0 μg/mL concentration levels (n = 3) respectively were as follows: intraday relative standard deviations 3.4 and 3.3%; interday relative standard deviations 5.0 and 4.3%; fiber-to-fiber relative standard deviations 6.0 and 3.5%. The relative recovery values were 90.3 and 101.4% at 0.01 and 1.0 μg/mL spiking levels, respectively. The proposed method was successfully applied to various real samples containing α-bisabolol.
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Abstract

A novel sol–gel coating on a stainless-steel fiber was developed for the first time for the headspace solid-phase microextraction and determination of α-bisabolol with gas chromatography and flame ionization detection. The parameters influencing the efficiency of solid-phase microextraction process, such as extraction time and temperature, pH and ionic strength were optimized by experimental design method. Under optimized conditions, the linear range was between 0.0027 and 100 μg/mL. The relative standard deviations determined at 0.01 and 1.0 μg/mL concentration levels (= 3) respectively were as follows: intraday relative standard deviations 3.4 and 3.3%; interday relative standard deviations 5.0 and 4.3%; fiber-to-fiber relative standard deviations 6.0 and 3.5%. The relative recovery values were 90.3 and 101.4% at 0.01 and 1.0 μg/mL spiking levels, respectively. The proposed method was successfully applied to various real samples containing α-bisabolol.

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Graphene-doped electrochemical copolymer coating of 2,2-bithiophene and 3-methylthiophene for the highly effective solid-phase microextraction of volatile benzene homologues

We report the electrochemical fabrication of a poly(2,2-bithiophene-co-3-methylthiophene)-graphene composite coating and its application in the headspace solid-phase microextraction and gas chromatography determination of benzenes (i.e., bromobenzene, 4-bromotoluene, 2-nitrotoluene, 3-nitrotoluene, 1,2,4-trichlorobenzene). The coating was uniform and showed cauliflower-like microstructure. It had high thermal stability (up to 375°C) and could be used for at least 180 times of solid-phase microextraction without a decrease of extraction performance. Furthermore, it presented high extraction capacity for the benzenes due to the hydrophobic effect and π–π interaction between the analytes and the coating. Under optimized extraction conditions, good linearity (correlation coefficients higher than 0.9946), wide linear range (0.01–50 μg L−1), low limits of detection (5.25–12.5 ng L−1) were achieved for these analytes. The relative standard deviation was lower than 5.7% for five successive measurements with one fiber, and the relative standard deviation for fiber-to-fiber was 4.9–6.8% (n = 5). The solid-phase microextraction and gas chromatography method was successfully applied for the determination of three real samples, and the recoveries for standards added were 89.6–106% for nail polish, 85.8–110% for hair dye and 90–106.2% for correction fluid, respectively.
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Abstract

We report the electrochemical fabrication of a poly(2,2-bithiophene-co-3-methylthiophene)-graphene composite coating and its application in the headspace solid-phase microextraction and gas chromatography determination of benzenes (i.e., bromobenzene, 4-bromotoluene, 2-nitrotoluene, 3-nitrotoluene, 1,2,4-trichlorobenzene). The coating was uniform and showed cauliflower-like microstructure. It had high thermal stability (up to 375°C) and could be used for at least 180 times of solid-phase microextraction without a decrease of extraction performance. Furthermore, it presented high extraction capacity for the benzenes due to the hydrophobic effect and π–π interaction between the analytes and the coating. Under optimized extraction conditions, good linearity (correlation coefficients higher than 0.9946), wide linear range (0.01–50 μg L−1), low limits of detection (5.25–12.5 ng L−1) were achieved for these analytes. The relative standard deviation was lower than 5.7% for five successive measurements with one fiber, and the relative standard deviation for fiber-to-fiber was 4.9–6.8% (n = 5). The solid-phase microextraction and gas chromatography method was successfully applied for the determination of three real samples, and the recoveries for standards added were 89.6–106% for nail polish, 85.8–110% for hair dye and 90–106.2% for correction fluid, respectively.

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Simultaneous determination of 29 pharmaceuticals in fish muscle and plasma by ultrasonic extraction followed by SPE–UHPLC–MS/MS

A confirmatory method for the simultaneous detection of 29 pharmaceuticals in fish muscle and plasma was developed by using solid-phase extraction combined with ultra high performance liquid chromatography and tandem mass spectrometry. Fish samples were extracted with methanol and enriched using Oasis HLB solid-phase extraction columns in one step. Twenty-nine target pharmaceuticals were quantified by the internal standard method and the calibration curves showed good linearity in a wide range with determination coefficients of greater than 0.913. The detection limits of the pharmaceuticals ranged from 0.01 to 2.00 μg/kg (μg/L). The applicability of the method was checked by precision and recovery experiments. The average recoveries of the 29 pharmaceuticals were between 61 and 111%, and all the relative standard deviations were below 25%. Our reported method has been demonstrated to be sensitive, convenient, rapid and reliable for the simultaneous determination of 29 pharmaceuticals in fish muscle and plasma. Real sample determination showed that 25 and 9 of the 29 compounds were detected in fish muscle and plasma, respectively.
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Abstract

A confirmatory method for the simultaneous detection of 29 pharmaceuticals in fish muscle and plasma was developed by using solid-phase extraction combined with ultra high performance liquid chromatography and tandem mass spectrometry. Fish samples were extracted with methanol and enriched using Oasis HLB solid-phase extraction columns in one step. Twenty-nine target pharmaceuticals were quantified by the internal standard method and the calibration curves showed good linearity in a wide range with determination coefficients of greater than 0.913. The detection limits of the pharmaceuticals ranged from 0.01 to 2.00 μg/kg (μg/L). The applicability of the method was checked by precision and recovery experiments. The average recoveries of the 29 pharmaceuticals were between 61 and 111%, and all the relative standard deviations were below 25%. Our reported method has been demonstrated to be sensitive, convenient, rapid and reliable for the simultaneous determination of 29 pharmaceuticals in fish muscle and plasma. Real sample determination showed that 25 and 9 of the 29 compounds were detected in fish muscle and plasma, respectively.

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Simple determination of some anti-dementia drugs in wastewater and human plasma samples by tandem dispersive liquid–liquid microextraction followed by HPLC

In this work, a simple method, namely, tandem dispersive liquid–liquid microextraction, with a high sample clean-up is applied for the rapid determination of the anti-dementia drugs rivastigmine and donepezil in wastewater and human plasma samples. This method, which is based upon two consecutive dispersive microextractions, is performed in 7 min. In the method, using a fast back-extraction step, the applicability of the dispersive microextraction methods in complicated matrixes is conveniently improved. This step can be performed in less than 2 min, and very simple tools are required for this purpose. To achieve the best extraction efficiency, optimization of the variables affecting the method was carried out. Under the optimized experimental conditions, the relative standard deviations for the method were in the range of 6.9–8.7%. The calibration curves were obtained in the range of 2–1100 ng mL−1 with good correlation coefficients, higher than 0.995, and the limits of detection ranged between 0.5 and 1.0 ng mL−1.
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Abstract

In this work, a simple method, namely, tandem dispersive liquid–liquid microextraction, with a high sample clean-up is applied for the rapid determination of the anti-dementia drugs rivastigmine and donepezil in wastewater and human plasma samples. This method, which is based upon two consecutive dispersive microextractions, is performed in 7 min. In the method, using a fast back-extraction step, the applicability of the dispersive microextraction methods in complicated matrixes is conveniently improved. This step can be performed in less than 2 min, and very simple tools are required for this purpose. To achieve the best extraction efficiency, optimization of the variables affecting the method was carried out. Under the optimized experimental conditions, the relative standard deviations for the method were in the range of 6.9–8.7%. The calibration curves were obtained in the range of 2–1100 ng mL−1 with good correlation coefficients, higher than 0.995, and the limits of detection ranged between 0.5 and 1.0 ng mL−1.

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Application of sunflower stalk-carbon nitride nanosheets as a green sorbent in the solid-phase extraction of polycyclic aromatic hydrocarbons followed by HPLC

A green biocomposite of sunflower stalks and graphitic carbon nitride nanosheets has been applied as a solid-phase extraction adsorbent for sample preparation of five polycyclic aromatic hydrocarbons in different solutions using high-performance liquid chromatography with UV detection. Before the modification, sunflower stalks exhibited relatively low adsorption to the polycyclic aromatic hydrocarbons extraction. The modified sunflower stalks showed increased adsorption to the analytes extraction due to the surface increasing and existence of a π–π interaction between the analytes and graphitic carbon nitride nanosheets on the surface. Under the optimal conditions, the limits of detection and quantification for five polycyclic aromatic hydrocarbons compounds could reach 0.4–32 and 1.2–95 ng L−1, respectively. The method accuracy was evaluated using recovery measurements in spiked real samples and good recoveries from 71 to 115% with relative standard deviations of less than 10% have been achieved. The developed method was successfully applied for polycyclic aromatic hydrocarbons determination in various samples: well water, tap water, soil, vegetable and barbequed meat (Kebab), with analytes contents ranging from 0.065 to 13.3 μg L−1. The prepared green composite as a new sorbent has some advantages including ease of preparation, low cost and good reusability.
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Abstract

A green biocomposite of sunflower stalks and graphitic carbon nitride nanosheets has been applied as a solid-phase extraction adsorbent for sample preparation of five polycyclic aromatic hydrocarbons in different solutions using high-performance liquid chromatography with UV detection. Before the modification, sunflower stalks exhibited relatively low adsorption to the polycyclic aromatic hydrocarbons extraction. The modified sunflower stalks showed increased adsorption to the analytes extraction due to the surface increasing and existence of a π–π interaction between the analytes and graphitic carbon nitride nanosheets on the surface. Under the optimal conditions, the limits of detection and quantification for five polycyclic aromatic hydrocarbons compounds could reach 0.4–32 and 1.2–95 ng L−1, respectively. The method accuracy was evaluated using recovery measurements in spiked real samples and good recoveries from 71 to 115% with relative standard deviations of less than 10% have been achieved. The developed method was successfully applied for polycyclic aromatic hydrocarbons determination in various samples: well water, tap water, soil, vegetable and barbequed meat (Kebab), with analytes contents ranging from 0.065 to 13.3 μg L−1. The prepared green composite as a new sorbent has some advantages including ease of preparation, low cost and good reusability.

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A combination of dispersive liquid–liquid microextraction and surface plasmon resonance sensing of gold nanoparticles for the determination of ziram pesticide

We have developed a reliable, fast, and highly sensitive analytical method utilizing dispersive liquid–liquid microextraction and gold nanoparticles probes for ziram (zinc bis(dimethyldithiocarbamate)) determination. The method is based on the in situ formation of gold nanoparticles in carbon tetrachloride as an organic phase. It was found that the trace levels of ziram influenced the formation of gold nanoparticles, leading to absorbance change of a sedimented phase. The results of the colorimetric ziram determination were in the concentration range of 0.12–2.52 ng/mL with a limit of detection of 0.06 ng/mL. The formation of the stable and dispersed gold nanoparticles in the organic phase provides a good precision for dispersive liquid–liquid microextraction method, resulting in the relative standard deviation of 3.8 and 1.2% for 0.56 and 1.58 ng/mL of ziram, respectively. This method has been successfully used for the ziram determination in samples of well and river water, soil, potato, carrot, wheat, and paddy soil.

Abstract

We have developed a reliable, fast, and highly sensitive analytical method utilizing dispersive liquid–liquid microextraction and gold nanoparticles probes for ziram (zinc bis(dimethyldithiocarbamate)) determination. The method is based on the in situ formation of gold nanoparticles in carbon tetrachloride as an organic phase. It was found that the trace levels of ziram influenced the formation of gold nanoparticles, leading to absorbance change of a sedimented phase. The results of the colorimetric ziram determination were in the concentration range of 0.12–2.52 ng/mL with a limit of detection of 0.06 ng/mL. The formation of the stable and dispersed gold nanoparticles in the organic phase provides a good precision for dispersive liquid–liquid microextraction method, resulting in the relative standard deviation of 3.8 and 1.2% for 0.56 and 1.58 ng/mL of ziram, respectively. This method has been successfully used for the ziram determination in samples of well and river water, soil, potato, carrot, wheat, and paddy soil.

Silicon carbide nanomaterial as a coating for solid-phase microextraction

Silicon carbide has excellent properties, such as corrosion resistance, high strength, oxidation resistance, high temperature, and so on. Based on these properties, silicon carbide was coated on stainless-steel wire and used as a solid-phase microextraction coating, and polycyclic aromatic hydrocarbons were employed as model analytes. Using gas chromatography, some important factors that affect the extraction efficiency were optimized one by one, and an analytical method was established. The analytical method showed wide linear ranges (0.1–30, 0.03–30, and 0.01–30 μg/L) with satisfactory correlation coefficients (0.9922–0.9966) and low detection limits (0.003–0.03 μg/L). To investigate the practical application of the method, rainwater and cigarette ash aqueous solution were collected as real samples for extraction and detection. The results indicate that silicon carbide has excellent application in the field of solid-phase microextraction.

Abstract

Silicon carbide has excellent properties, such as corrosion resistance, high strength, oxidation resistance, high temperature, and so on. Based on these properties, silicon carbide was coated on stainless-steel wire and used as a solid-phase microextraction coating, and polycyclic aromatic hydrocarbons were employed as model analytes. Using gas chromatography, some important factors that affect the extraction efficiency were optimized one by one, and an analytical method was established. The analytical method showed wide linear ranges (0.1–30, 0.03–30, and 0.01–30 μg/L) with satisfactory correlation coefficients (0.9922–0.9966) and low detection limits (0.003–0.03 μg/L). To investigate the practical application of the method, rainwater and cigarette ash aqueous solution were collected as real samples for extraction and detection. The results indicate that silicon carbide has excellent application in the field of solid-phase microextraction.

Magnetic iron(III)-based framework composites for the magnetic solid-phase extraction of fungicides from environmental water samples

We adopted a facile hydrofluoric acid-free hydro-/solvothermal method for the preparation of four magnetic iron(III)-based framework composites (MIL-101@Fe3O4-COOH, MIL-101-NH2@Fe3O4-COOH, MIL-53@Fe3O4-COOH, and MIL-53-NH2@Fe3O4-COOH). The obtained four magnetic iron(III)-based framework composites were applied to magnetic separation and enrichment of the fungicides (prochloraz, myclobutanil, tebuconazole, and iprodione) from environmental samples before high-performance liquid chromatographic analysis. MIL-101-NH2@Fe3O4-COOH showed more remarkable pre-concentration ability for the fungicides as compared to the other three magnetic iron(III)-based framework composites. The extraction parameters affecting enrichment efficiency including extraction time, sample pH, elution time, and the desorption solvent were investigated and optimized. Under the optimized conditions, the standard curve of correlation coefficients were all above 0.991, the limits of detection were 0.04–0.4 μg/L, and the relative standard deviations were below 10.2%. The recoveries of two real water samples ranged from 71.1–99.1% at the low spiking level (30 μg/L). Therefore, the MIL-101-NH2@Fe3O4-COOH composites are attractive for the rapid and efficient extraction of fungicides from environmental water samples.

Abstract

We adopted a facile hydrofluoric acid-free hydro-/solvothermal method for the preparation of four magnetic iron(III)-based framework composites (MIL-101@Fe3O4-COOH, MIL-101-NH2@Fe3O4-COOH, MIL-53@Fe3O4-COOH, and MIL-53-NH2@Fe3O4-COOH). The obtained four magnetic iron(III)-based framework composites were applied to magnetic separation and enrichment of the fungicides (prochloraz, myclobutanil, tebuconazole, and iprodione) from environmental samples before high-performance liquid chromatographic analysis. MIL-101-NH2@Fe3O4-COOH showed more remarkable pre-concentration ability for the fungicides as compared to the other three magnetic iron(III)-based framework composites. The extraction parameters affecting enrichment efficiency including extraction time, sample pH, elution time, and the desorption solvent were investigated and optimized. Under the optimized conditions, the standard curve of correlation coefficients were all above 0.991, the limits of detection were 0.04–0.4 μg/L, and the relative standard deviations were below 10.2%. The recoveries of two real water samples ranged from 71.1–99.1% at the low spiking level (30 μg/L). Therefore, the MIL-101-NH2@Fe3O4-COOH composites are attractive for the rapid and efficient extraction of fungicides from environmental water samples.

Preparation of iron-based MIL-101 functionalized polydopamine@Fe3O4 magnetic composites for extracting sulfonylurea herbicides from environmental water and vegetable samples

Here, we describe a simple one-pot solvothermal method for synthesizing MIL-101(Fe)@polydopamine@Fe3O4 composites from polydopamine-modified Fe3O4 particles. The composite was used as a magnetic adsorbent to rapidly extract sulfonylurea herbicides. The herbicides were then analyzed by high-performance liquid chromatography. The best possible extraction efficiencies were achieved by optimizing the most important extraction parameters, including desorption conditions, extraction time, adsorbent dose, salt concentration, and the pH of the solution. Good linearity was found (correlation coefficients > 0.9991) over the herbicide concentration range 1–150 μg L−1 using the optimal conditions. The limits of detection (the concentrations giving signal/noise ratios of 3) were low, at 0.12–0.34 μg L−1, and repeatability was good (the relative standard deviations were < 4.8%, n = 6). The method was used successfully to determine four sulfonylurea herbicides in environmental water and vegetable samples, giving satisfactory recoveries of 87.1–108.9%. The extraction efficiency achieved using MIL-101(Fe)@polydopamine@Fe3O4 was compared with the extraction efficiencies achieved using other magnetic composites (polydopamine@Fe3O4, Hong Kong University of Science and Technology (HKUST)-1@polydopamine@Fe3O4, and MIL-100(Fe)@polydopamine@Fe3O4). The results showed that the magnetic MIL-101(Fe)@polydopamine@Fe3O4 composites have great potential for the extraction of trace sulfonylurea herbicides from various sample types.
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Abstract

Here, we describe a simple one-pot solvothermal method for synthesizing MIL-101(Fe)@polydopamine@Fe3O4 composites from polydopamine-modified Fe3O4 particles. The composite was used as a magnetic adsorbent to rapidly extract sulfonylurea herbicides. The herbicides were then analyzed by high-performance liquid chromatography. The best possible extraction efficiencies were achieved by optimizing the most important extraction parameters, including desorption conditions, extraction time, adsorbent dose, salt concentration, and the pH of the solution. Good linearity was found (correlation coefficients > 0.9991) over the herbicide concentration range 1–150 μg L−1 using the optimal conditions. The limits of detection (the concentrations giving signal/noise ratios of 3) were low, at 0.12–0.34 μg L−1, and repeatability was good (the relative standard deviations were < 4.8%, n = 6). The method was used successfully to determine four sulfonylurea herbicides in environmental water and vegetable samples, giving satisfactory recoveries of 87.1–108.9%. The extraction efficiency achieved using MIL-101(Fe)@polydopamine@Fe3O4 was compared with the extraction efficiencies achieved using other magnetic composites (polydopamine@Fe3O4, Hong Kong University of Science and Technology (HKUST)-1@polydopamine@Fe3O4, and MIL-100(Fe)@polydopamine@Fe3O4). The results showed that the magnetic MIL-101(Fe)@polydopamine@Fe3O4 composites have great potential for the extraction of trace sulfonylurea herbicides from various sample types.

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