Based on the excellent performances of nanocrystalline cellulose, sodium alginate, or K-carrageenan in Pb
2+
adsorption, nanocrystalline cellulose/sodium alginate/K-carrageenan composite hydrogel ...beads were prepared to adsorb Pb(II) from aqueous solutions. The objective of this study was to demonstrate the excellent potential of the composite hydrogel beads for heavy metal ion adsorption. We successfully prepared ecofriendly Fe-modified nanocrystalline cellulose/sodium alginate/K-carrageenan composite hydrogel beads and characterized them. The structure and adsorption mechanism were investigated using scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy, and the optimal adsorption conditions were determined. The tricomponent hydrogel beads were robust and exhibited improved adsorption capacity for Pb
2+
and good reusability. The adsorption results could be fitted well with a pseudo-second-order kinetic model and the Langmuir adsorption model. The maximum adsorption capacity obtained by fitting was 351.04 mg g
−1
. Recycling experiments revealed that the adsorption capacity of the adsorbent remained high after five cycles of reuse.
•A surface molecularly imprinted polymers (MIPs) based on dopamine-coated magnetic nanoparticles were successfully prepared.•The maximum adsorption capacity of the MIPs for gatifloxacin is ...51.9 mg/g.•The obtained MIPs had a high specific surface area, good superparamagnetism, and excellent selectivity for the target fluoroquinolone.
To address problems such as environmental accumulation, improved methods are required for the detection and analysis of fluoroquinolones. Herein, we prepared a surface molecularly imprinted polymer (MIP) based on dopamine-coated magnetic nanoparticles. The performance of this MIP as a novel adsorbent for fluoroquinolones was analyzed using high-performance liquid chromatography. Furthermore, the morphology and physicochemical properties of the prepared material were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, Brunauer–Emmett–Teller surface area analysis, and vibrating sample magnetometry. The synthesized molecules consisted of a core–shell constitution with a Fe3O4 nucleus and a polydopamine enclosure, the surface of which was imprinted using gatifloxacin as a template molecule. The obtained polymers had a high specific surface area, good superparamagnetism, and excellent selectivity of the target molecules. Under optimal adsorption conditions, the ultimate loading capacity of gatifloxacin on the MIP was 51.9 mg/g, with an equilibrium adsorption time of 30 min and an imprinting factor of 2.24. After six cycles, the adsorption capacity of this adsorbent did not decrease significantly. For the analytical characteristics of the method, we inserted the application part of the sample in the local river water. Through the spiked recovery of the three FQs aqueous solutions, it was found that their spiked recovery, LOD, and LOQ were 84.1–91.9%, 6.4–9.9 ng mL−1, and 17.8–34.5 ng mL−1, respectively. Owing to its adsorption selectivity and recyclability, this magnetic MIP is a promising adsorbent for sample separation and pretreatment applications.
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To date, knowledge of internal human exposure to BPA and its analogues (particularly bisphenol S and bisphenol F, etc.) remains limited. In the present study, a method involving dispersive ...solid-phase extraction and LC/MS was proposed to investigate the contamination levels of 28 precursor bisphenols and 9 major metabolites in serum. The critical variables of preparation method were screened out by Plackett-Burman design and further optimized by central composite design. Left in optimal conditions, a total of 286 samples consisting of 153 males and 133 females were analyzed. The results showed that BPA dominated over all the cases with the highest positive rate (82.2% of all the surveyed people), and totally four metabolites (BPA β-D-glucuronide, BPA monosulfate, BPA bis-(β-D-glucuronide) and BPS monosulfate) were detectable. The occurrence of BPA bis-(β-D-glucuronide) in serum is reported for the first time and its higher positive rate and contamination concentrations suggested that it may be a more important metabolite of BPA than others. Negligible potential risk of health effects to blood donors was observed, since the estimated exposure levels (mean 32.1 ng/kg bw/day, 95th 123.2 ng/kg bw/day) were well below far less than the temporary tolerable reference dose of BPA that recommended by the European Food Safety Authority (4 μg/kg bw/day by). The reference level of BPA for healthy population was determined to be 4.09 μg/L via the percentile method.
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•A new approach to direct analysis of bisphenols and metabolites in serum was proposed.•The results showed that BPA (82.2%) and totally four metabolites were detectable.•The predominant metabolite of BPA in serum should be BPA bis-(β-D-glucuronide).•No obvious health risks have been identified for healthy adults in China.
Surface modification of cellulose nanocrystals (CNC) is essential for improving their reactivity and adsorption capacity. Oxidation, as a conventional modification method of CNC, has strong reaction ...conditions, which may partially destroy the structure of CNCs. Herein, we propose a mild cellulose modification method, in which diethylenetriaminepentaacetic acid (DPTA) was grafted onto CNC with an aminosilane coupling agent. To facilitate the enrichment and recovery of adsorbents, we prepared magnetic CNC before grafting DPTA, and finally obtained magnetic carboxylic functionalized CNC (MCNC-DPTA). The effects of the reaction parameters on the adsorption process were systematically studied by transmission electron microscopy, X-ray diffraction, Vibration sample magnetometry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Additionally, the effects of the solution pH, the initial concentration of Pb, and the adsorption time on the adsorption properties of the materials were evaluated. Furthermore, the structure, morphology, and thermal properties of the solution were systematically studied. After 6 cycle tests, the adsorption amount of Pb(II) by MCNC-DPTA was only reduced by 7%. These results show that MCNC-DPTA is an environment-friendly adsorption material with an excellent Pb(II) removal effect.
•An effective d-μ-SPE procedure with CS-NR-Mag-MIP adsorbent has been developed for extraction of 22 SAs.•The proposed sample preparation procedure is environmental friendly, less time and ...solvent-consuming.•A novel d-μ-SPE UFLC-MS/MS method for analysis of 22 SAs in chicken breast muscle has been developed.•LOQs are significantly lower than other reported LC-MS/MS-based methodologies.
A novel, simple and sensitive method was developed for the simultaneous determination of 22 sulfonamides (SAs) in chicken breast muscle by using the dispersive micro-solid-phase extraction (d-μ-SPE) procedure combined with ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC-MS/MS). The excellent core–shell nanoring amino-functionalized superparamagnetic molecularly imprinted polymer (CS-NR-Mag-MIP) was used as sorbent, and the main factors affecting the extraction efficiency were investigated in detail. All target compounds showed good linearities in the tested range with correlation coefficients (r) higher than 0.9980. The mean recoveries were in the range of 85.0–112.2% at low, medium and high concentration levels (0.1, 1.0 and 5.0ng/g). The intra-day and inter-day relative standard deviations (RSDs) were lower than 6.0% and 8.9%, respectively. The limits of quantification for the 22 SAs were between 0.013 and 0.099ng/g. The developed d-μ-SPE-UFLC-MS/MS method had been successfully applied to the chicken breast muscle samples for food-safety risk monitoring in Zhejiang Province, China. The results showed sulfamethazine, sulfamethoxazole and sulfaquinoxaline in five out of three hundred collected samples were detected with concentrations of 0.418–2.28, 16.4 and 2.93ng/g, respectively. It was confirmed that the CS-NR-Mag-MIP was a kind of highly effective d-μ-SPE materials used for the SAs analyses.
•A reliable method was developed for the analysis of four bisphenols in foodstuffs.•Plackett-Burman design and response surface methodology were used to determine the optimal conditions.•Dietary ...exposure assessment was performed combining the contamination monitoring data and daily food consumption.
An effective method has been developed for the simultaneous determination of four bisphenols (bisphenol A, S, F and B) in various foodstuffs. The contaminants were extracted by QuEChERS-based strategy and subjected to ion-exchange solid-phase extraction for further clean-up. The critical variables were screened by Plackett-Burman design and then optimized by central composite design. Under the optimized conditions, satisfactory accuracy (recoveries 76%–116%) and precision (RSDs < 12%) were achieved. The established method was then used to assess the contamination status of 379 real samples. Bisphenol A was demonstrated to be the predominant bisphenol with highest incidence (79.7%) and average concentration (14.3 μg/kg). The positive rates (mean concentration) of bisphenol S, F and B were 37.7% (1.6 μg/kg), 26.9% (1.4 μg/kg) and 0.0% (not detected), respectively. Finally, the daily dietary intakes of ∑4bisphenolsfor adult residents were estimated (55.9–76.1 ng/kg bw/day) according to the contamination concentrations and the daily recommended intakes.
•The effect of cross-linker used in the co-polymerization on the recovery of analytes has been studied.•An effective M-dSPE procedure has been developed for extraction of 7 synthetic pigments.•The ...NH2-LDC-MP sorbents could be efficiently regenerated and reused.•The NH2-LDC-MP more effectively remove matrix than the PSA materials.•A novel M-dSPE UFLC-MS/MS method for analysis of 7 synthetic pigments in wine and soft drinks has been developed.
A novel, simple and sensitive method based on the use of magnetic dispersive solid-phase extraction (M-dSPE) procedure combined with ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC–MS/MS) was developed to determine seven synthetic pigments (tartrazine, amaranth, carmine, sunset yellow, allura red, brilliant blue and erythrosine) in wines and soft drinks. An amino-functionalized low degrees of cross-linking magnetic polymer (NH2-LDC-MP) was synthesized via suspension polymerization, and characterized by transmission electron microscopy (TEM). The NH2-LDC-MP was used as the M-dSPE sorbent to remove the matrix from the solution, and the main factors affecting the extraction were investigated in detail. The obtained results demonstrated the higher extraction capacity of NH2-LDC-MP with recoveries between 84.0 and 116.2%. The limits of quantification (LOQs) for the seven synthetic pigments were between 1.51 and 5.0μg/L in wines and soft drinks. The developed M-dSPE UFLC–MS/MS method had been successfully applied to the real wines and soft drinks for food-safety risk monitoring in Zhejiang Province, China. The results showed that sunset yellow was in three out of thirty soft drink samples (2.95–42.6μg/L), and erythrosine in one out of fifteen dry red wine samples (3.22μg/L), respectively. It was confirmed that the NH2-LDC-MP was a kind of highly effective M-dSPE materials for the pigments analyses.
Bimetallic oxide CuFeO2 as a new heterogeneous catalyst has shown much higher catalytic ability for activating peroxide than single-metal oxides. The present work demonstrated a synergistic microwave ...(MW) enhanced Fenton-like process with CuFeO2 for rapid decolorization of azo dye Orange G (OG). The MW irradiation dramatically enhanced the OG degradation efficiency, achieving 99.9% decolorization within 15min at pH5. The XRD analysis of reused CuFeO2, together with metal leaching tests, indicated merits of recycling for CuFeO2. The subsequent surface element analysis by XPS for fresh and used CuFeO2 showed a complex network for reactions between copper-iron redox pairs and surface hydroxyl groups, leading to a synergistic Fenton-like system accelerated by MW irradiation. In the CuFeO2 initiated Fenton-like reactions, several oxidant species (i.e., OH, O2−, electron hole, and FeIVO) responsible to the OG oxidation were identified by quenching experiments, showing the MW generated high temperature and “hot spots” enhanced the yield of OH by generation of electron-hole pairs. Further, the 26 detected degradation products confirmed the OH dominant oxidation of OG. This study shows that the MW-enhanced Fenton-like reaction using CuFeO2 has potential applications for rapid decolorization of dye effluent.
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•Microwave induced synergism in CuFeO2 based Fenton-like process.•OG was completely degraded with negligible Cu and Fe ions leached.•OH, O2–, electron hole, and FeIVO were responsible for the OG oxidation.•Pathways for OG oxidation were verified by 26 degradation products detected.
•An investigation on the contamination of multiple mycotoxins in edible oils was conducted.•Representative mycotoxins and distribution features vary depending on the types of edible oils.•The risk of ...ingestion of mycotoxins from edible oil is usually acceptable.•Attention should be paid to the intakes of aflatoxins and alternariol monomethyl ether.
In this study, the contamination of 51 mycotoxins in 416 edible oils were determined by UPLC-MS/MS. Totally, twenty-four mycotoxins were detected and nearly half of the samples (46.9%, n = 195) were contaminated simultaneously with six to nine kinds of mycotoxins. The predominant mycotoxins and contamination characteristics varied depending on the type of oils. More specifically, four enniatins, alternariol monomethyl ether (AME) and zearalenone were the most frequent combination. Overall, peanut and sesame oils (10.7–11.7 mycotoxins on average) were found to be the most contaminated matrices whereas camellia and sunflower seed oils (1.8–2.7 species) were the opposite. Dietary exposure risks of mycotoxins were acceptable in most cases, however, the ingestion of aflatoxins (especially aflatoxin B1) through peanut and sesame oil (margin of exposure: 239.4–386.3 < 10000) exceeded the acceptable carcinogenic risk level. Meanwhile, the risks of cumulative ingestion through the food chain should be of great concern, especially sterigmatocystin, ochratoxin A, AME and zearalenone.
•Occurrences of 43 mycotoxins have been surveyed in 170 chestnut and jujube samples.•Central composite design has been conducted to determine the optimal conditions.•Suspected presences were further ...identified using high-resolution orbitrap MS.•Special attention should be paid to the contamination of mycotoxins in chestnut flour.
A rapid and efficient QuEChERS-based preparation method was established for the simultaneous determination of 43 mycotoxins in chestnut and jujube (Chinese date). The contaminants were extracted using acetonitrile and subjected to dispersive solid-phase extraction for further clean-up. Central composite design was conducted to overcome the limitations of conventional optimization methods, and assess the interaction effects between variables and reach the true optimal conditions. Quantitative analysis was performed on UHPLC-MS/MS with the aid of stable isotope internal standards and matrix-matched curves, whereas qualitative identification was carried out by using high-resolution MS based on exact masses and fragmentation patterns. In addition to the mycotoxins that are routinely monitored (like aflatoxins, ochratoxin A, etc.), this study also revealed a non-negligible contamination of zearalenone (56/170), beauvericin (52/170), enniatin B (43/170), and alternariol monomethyl ether (42/170) in chestnut and jujube, especially the chestnut flour.
