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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.

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.

Correction for ‘In situ controllable synthesis of graphene oxide-based ternary magnetic molecularly imprinted polymer hybrid for efficient enrichment and detection of eight microcystins’ by Sheng-Dong Pan et al., J. Mater. Chem. A, 2015, 3, 23042–23052.

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.

Correction for ‘Synthesis of a monodisperse well-defined core–shell magnetic molecularly-imprinted polymer prior to LC-MS/MS for fast and sensitive determination of mycotoxin residues in rice’ by Sheng-Dong Pan et al., Anal. Methods, 2017, 9, 5281–5292.

Correction for ‘Surface core–shell magnetic polymer modified graphene oxide-based material for 2,4,6-trichlorophenol removal’ by Mei-Lan Chen et al., RSC Adv., 2014, 4, 63494–63501.

Correction for ‘Controlled synthesis of pentachlorophenol-imprinted polymers on the surface of magnetic graphene oxide for highly selective adsorption’ by Sheng-Dong Pan et al., J. Mater. Chem. A, 2014, 2, 15345–15356.

A novel well-designed graphene oxide-based magnetic polymer (GO-Fe3O4@P) has been successfully synthesized via distillation–precipitation polymerization, ring-opening and amidation reactions. The as-prepared GO-Fe3O4@P was further characterized by transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), BET analysis, zeta potential analysis, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) and the characterization results revealed that core–shell structural Fe3O4@P microspheres were covalently bonded onto the GO sheet. The adsorption characteristics of the GO-Fe3O4@P intended for removal of 2,4,6-trichlorophenol (2,4,6-TCP) were investigated. Batch adsorption studies were carried out to optimize adsorption conditions. The effect of solution pH, adsorption isotherm, kinetics, and thermodynamics was deeply investigated. The results indicated that the adsorption property of GO-Fe3O4@P was highly pH dependent and the adsorption mechanism referred to hydrogen bond and π–π stacking interactions. The adsorption data for 2,4,6-TCP onto GO-Fe3O4@P was well fitted to a Langmuir isotherm. The maximum adsorption capacity (qm) of GO-Fe3O4@P to 2,4,6-TCP was found to be 232.6 mg g−1. Kinetic results showed that the adsorption reached equilibrium within 4 min, 10 min, and 60 min for initial 2,4,6-TCP concentrations of 10 mg L−1, 100 mg L−1, and 500 mg L−1, respectively. The data of adsorption kinetics obeyed the pseudo-second-order rate model well. Thermodynamic parameters such as ΔHθ, ΔSθ, and ΔGθ for the 2,4,6-TCP adsorption onto GO-Fe3O4@P have been estimated, suggesting the adsorption process was endothermic and entropy favored in nature.

An accurate and sensitive method has been developed for the determination of PCBs in water by gas chromatography coupled with mass spectrometry (GC/MS) with ionic liquid based headspace single-drop microextraction under ultrasound. The sample injection part of gas chromatographic instrument was modifed to avoid the ionic liquid leaking, selected 1-butyl-3-methylimidazolium hexafluorophosphate ([C4MI[PF6]) as extracting agents. Experimental parameters influencing the extraction performance, such as desorption temperature, ultrasound extraction time, extraction temperature, ionic liquid headspace volume and salt effect, were optimized. Calibration curve was linear within the range of 10~300.0 μg/L, and the extraction recoveries with RSD values lower than 9.1% were from 77.6% to 103.3%. The limits of detections (LOD), calculated on the basis of signal-to-noise ratio of 3 (S/N=3), was in the range of 0.005~0.007 μg/L. This method is found to be simple, sensitive, little interferential and good specificity for the determination of trace PCBs in water. Real sea sample was successfully analyzed using this method.

Bimetallic oxide CuFeO

A new facile, rapid, inexpensive, and sensitive method for the analysis of six trace trichlorophenols in seawater samples was developed by magnetic micro-solid-phase extraction coupled to liquid chromatography with tandem mass spectrometry. Core-shell covalently functionalized ferroferric oxide coated with aminated silicon dioxide and decorated with multiwalled carbon nanotubes was applied as an adsorbent to perform the extraction process. The effect of factors including solution pH, contact time, adsorbent amount, and ionic strength were investigated in detail. The obtained results revealed that the proposed adsorbent was a highly effective and low-cost magnetic micro-solid-phase extraction material for the enrichment of 2,3,4-trichlorophenol, 2,3,5-trichlorophenol, 2,3,6-trichlorophenol, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, and 3,4,5-trichlorophenol from seawater. Under the optimized conditions, the recoveries ranged from 88.0 to 99.5% at the three spiking levels, the limits of detection and the limits of quantification were 0.002 and 0.007 μg/L for the six trichlorophenols, respectively. The intra- and interday relative standard deviations were 2.0-6.7 and 4.5-8.9%, respectively. The calibration curves showed a good linearity in the range of 0.02-5.0 μg/L. The routine run analyses showed that the developed method was fast, simple, accurate, solvent-saving and high resolution, and it was suitable for the determination of trace trichlorophenols in seawater.

A rapid, sensitive, and selective high‐performance liquid chromatography‐tandem mass spectrometric method (HPLC‐MS‐MS) for the determination of coumatetralyl in human serum using warfarin as an internal standard has been developed and validated. Coumatetralyl and the internal standard were extracted from the human serum samples by liquid‐liquid extraction with ethyl acetate, followed by separation on a XDB C18 reversed‐phase column (150 mm×2.1 mm i.d., 5 µm) using a mobile phase consisting of acetic acid‐ammonium acetate (5 mmol/L, pH=4.5)/methanol (20:80, v/v) at a constant flow rate of 0.40 mL/min. Coumatetralyl and the internal standard were ionized by negative ion pneumatically assisted electrospray and detected in the multiple‐reaction monitoring mode using precursor→product ion combinations at m/z 291→247 and 307→161, respectively. The calibration curve was linear (r2=0.9945) in the concentration range of 0.5∼100.0 ng/mL, with a lower limit of quantification of 0.5 ng/mL in human serum. Int...

Wilfortrine, wilfordine, wilforgine and wilforine are four major bioactive sesquiterpene alkaloids in Tripterygium wilfordii Hook. F. The first analytical determination of the four major bioactive alkaloids is described. The four alkaloids are well-resolved within 15 min using the developed HPLC method. The identity of the analytes was confirmed by an HPLC-MS experiment, with all compounds being clearly assignable by atmospheric pressure chemical ionization (APCI) positive mode analysis. The method was validated for limit of qualification, linearity and inter-day variation of precision and accuracy. Seven T. wilfordii samples (extracts and commercial product) were successfully analysed.

A sensitive, fast, and accurate method to determine warfarin and coumatetralyl in serum by high performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC‐ESI‐MS) was developed. After warfarin and coumatetralyl in serum was extracted by ethyl acetate, a satisfactory separation was achieved on a XDB C18 column, 150 mm×2.1 mm×5 µm, by using the mobile phase consisting of acetic acid‐ammonium acetate (10 mmol/L, pH=4.5) (20%) and methanol (80%) in isocratic eluent at a constant flow rate of 0.30 mL/min. The molecular ions m/z [M‐H]− 307 and 291 were selected for the quantification in the selected ion monitoring (SIM) mode for warfarin and coumatetralyl, respectively. The linear range was 0.5∼100.0 µg/L for warfarin and coumatetralyl. The limit of quantification in serum was found to be 0.5 µg/L for each. The recoveries were between 91.9∼94.9% for warfarin and 90.9∼104.0% for coumatetralyl, the intra‐ and inter‐day RSDs for each were less than 10.1%. This method ca...

A novel, sensitive, and accurate method has been successfully developed for the simultaneous determination of 3 monochlorophenols (MCPs) in drinking water samples by ion chromatography (IC) coupled with atmospheric pressure chemical ionization mass spectrometry in the negative mode. Drinking water was preconcentrated by solid-phase extraction (SPE). The IC separation was carried out with an IonPac® AS18 analytical column (250 mm × 4.0 mm) and an IonPac® AG18 guard column (50 mm × 4.0 mm) using 15 mmol l −1 KOH containing 10% acetonitrile as mobile phase in the isocratic mode at a constant flow rate of 1.0 ml min −1 . The molecular ion m/z 127 [M-H] was selected for the quantification in the selected ion monitoring (SIM) mode. Within-the-day and day-to-day relative standard deviations were less than 8.6 and 10.5%, respectively. The limits of quantification (LOQs) in water samples were 0.02, 0.01, and 0.01 μg l −1 for 2-MCP, 3-MCP, and 4-MCP, respectively. The method allows the three target compounds in water samples to be determined at a level of ng ml −1 , and it has been successfully applied to the routine analyses.

A method to simultaneously determinate 19 chlorophenols (CPs) in water by liquid chromatography, coupled with atmospheric pressure chemical ionization mass spectrometry (LC‐APCI‐MS), and a solid‐phase extraction utilizing Oasis® HLB cartridges to preconcentrate the target analytes was developed. The method was linear in the range 0.5∼25.0 µg/L with a good correlation coefficient (r>0.996) for all CPs. The limits of detection (LODs) were 0.4∼30.0 ng/L, extraction recoveries were 87.5∼100.4%, intra‐day RSDs were 5∼12%, and inter‐day RSDs were 7∼15%. This method has been successfully applied to the analysis of water samples. In addition, a comparison was obtained between APCI‐MS and ESI‐MS for the determination of the 19 CPs.

A high-performance liquid chromatographic-tandem mass spectrometric (HPLC-MS-MS) assay was developed and validated to determine quantitatively flocoumafen and brodifacoum in whole blood using warfarin as an internal standard (IS). Liquid-liquid extraction, using ethyl acetate, was used to isolate flocoumafen, brodifacoum and the IS from the biological matrix. Detection was performed on a mass spectrometer by negative electrospray ionization (ESI) in multiple reaction monitoring (MRM) mode. The calibration curves were linear (r(2) > 0.998) in the concentration range of 0.1-100.0 ng ml(-1) with a lower limit of quantification of 0.05 ng ml(-1) for flocoumafen, and 0.1 ng ml(-1) for brodifacoum in whole blood. Intra-day and inter-day relative standard deviations (RSDs) were less than 8.0% and 10.8%, respectively. Recoveries of flocoumafen and brodifacoum ranged from 78.0% to 83.7%. This assay can be used to determine trace flocoumafen and brodifacoum in whole blood to investigate suspected poisoning of human and animals.

In this work, the decolorization of azo dye Orange G (OG) in aqueous solution by aluminum powder enhanced by ultrasonic irradiation (AlP-UI) was investigated. The effects of various operating operational parameters such as the initial pH, initial OG concentration, AlP dosage, ultrasound power and added hydrogen peroxide (H2O2) concentration were studied. The results showed that the decolorization rate was enhanced when the aqueous OG was irradiated simultaneously by ultrasound in the AlP-acid systems. The decolorization rate decreased with the increase of both initial pH values of 2.0–4.0 and OG initial concentrations of 10–80 mg/L, increased with the ultrasound power enhancing from 500 to 900 W. An optimum value was reached at 2.0 g/L of the AlP dosage in the range of 0.5–2.5 g/L. The decolorization rate enhanced significantly by the addition of hydrogen peroxide in the range of 10–100 mM to AlP-UI system reached an optimum value of 0.1491 min−1. The decolorization of OG appears to involve primarily oxidative steps, the cleavage of N N bond, which were verificated by the intermediate products of OG under the optimal tested degradation system, aniline and 1-amino-2-naphthol-6,8-disulfonate detected by the LC–MS.

A reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed for the simultaneous determination of nine food additives, i.e., acesulfame, saccharin, caffeine, aspartame, benzoic acid, sorbic acid, stevioside, dehydroacetic acid and neotame in red wine. The effects of ion-suppressors, i.e., trifluoroacetic acid (TFA) and ammonium acetate (AmAc) on retention behavior of nine food additives in RP-HPLC separation were discussed in detail. The relationships between retention factors of solutes and volume percent of ion-suppressors in the mobile-phase systems of acetonitrile-TFA aqueous solution and acetonitrile-TFA-AmAc aqueous solution were quantitatively established, respectively. The results showed that the ion suppressors had not only an ion suppression effect, but also an organic modification effect on the acidic analytes. The baseline separation of nine food additives was completed by a gradient elution with acetonitrile-TFA(0.01%, v/v)-AmAc(2.5 mmol L(-1)) aqueous solution as the mobile phase. The recoveries were between 80.2 - 99.5% for all analytes with RSDs in the range of 1.5 - 8.9%. The linearities were in the range of 0.2 - 100.0 mg L(-1) with determination coefficients (r(2)) higher than 0.9991 for all analytes. The limits of quantification (LOQs) were between 0.53 - 0.99 mg L(-1). The applicability of the proposed method to detect and quantify food additives has been demonstrated in the analysis of 30 real samples.

A novel and effective dispersive solid-phase extraction (dSPE) procedure with rapid magnetic separation using ethylenediamine-functionalized magnetic polymer as an adsorbent was developed. The new procedure had excellent clean-up ability for the selective removal of the matrix in red wine. An accurate, simple, and rapid analytical method using ultra-fast liquid chromatography–tandem quadrupole mass spectrometry (UFLC–MS/MS) for the simultaneous determination of nine food additives (i.e., acesulfame, saccharin, sodium cyclamate, aspartame, benzoic acid, sorbic acid, stevioside, dehydroacetic acid, and neotame) in red wine was also used and validated. Recoveries ranging from 78.5% to 99.2% with relative standard deviations ranging from 0.46% to 6.3% were obtained using the new method. All target compounds showed good linearities in the tested range with correlation coefficients ( r ) higher than 0.9993. The limits of quantification for the nine food additives were between 0.10 μg/L and 50.0 μg/L. The proposed dSPE–UFLC–MS/MS method was successfully applied in the food-safety risk monitoring of real red wine in Zhejiang Province, China.

A rapid, sensitive and selective high-performance liquid chromatography tandem mass spectrometric method (HPLC/MS–MS) has been developed and validated for the determination of bromadiolone in whole blood using warfarin as an internal standard (IS). Bromadiolone was extracted from the whole blood samples by liquid–liquid extraction with ethyl acetate. Multiple-reaction monitoring (MRM) was used to detect bromadiolone and IS, using precursor→product ion combinations at m / z 527→465 and 307→161, respectively. The calibration curve was linear ( r 2 =0.998) in the concentration range of 0.5–100.0ng/mL with a lower limit of quantification of 0.5ng/mL in whole blood. Intra- and inter-day relative standard deviations (R.S.D.s) were less than 7.5 and 11.9%, respectively. Recoveries of bromadiolone ranged from 82.1 to 85.2%. This method is found to be determined trace bromadiolone in whole blood and can be used in the diagnosis of the poisoned human beings.