Multiple mycotoxins in commonly used edible oils: Occurrence and evaluation of potential health risks.

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.

Nitrogen doped bimetallic sludge biochar composite for synergistic persulfate activation: Reactivity, stability and mechanisms.

As a recycling use of waste activated sludge (WAS), we used high-temperature pyrolysis of WAS to support bimetallic Fe-Mn with nitrogen (N) co-doping (FeMn@N-S), a customized composite catalyst that activates peroxysulphate (PS) for the breakdown of tetracycline (TC). First, the performance of TC degradation was evaluated and optimized under different N doping, pH, catalyst dosages, PS dosages, and contaminant concentrations. Activating PS with FeMn@N-S caused the degradation of 91% of the TC in 120 min. Next, characterization of FeMn@N-S by XRD, XPS and FT-IR analysis highlights N doping is beneficial to take shape more active sites and reduces the loss of Fe and Mn during the degradation reaction. As expected, the presence of Fe-Mn bimetallic on the catalyst surface increases the rate of electron transfer, promoting the redox cycle of the catalyst. Other functional groups on the catalyst surface, such as oxygen-containing groups, accelerated the electron transfer during PS activation. Free radical quenching and ESR analysis suggest that the main contributor to TC degradation is surface-bound SO4•-, along with the presence of single linear oxygen (1O2) oxidation pathway. Finally, the FeMn@N-S composite catalyst exhibits excellent pH suitability and reusability, indicating a solid practicality of this catalyst in PS-based removal of antibiotics from wastewater.

Silica enhanced activation and stability of Fe/Mn decorated sludge biochar composite for tetracycline degradation.

In this study, SiO2-composited biochar decorated with Fe/Mn was prepared by co-pyrolysis method. The degradation performance of the catalyst was evaluated by activating persulfate (PS) to degrade tetracycline (TC). The effects of pH, initial TC concentration, PS concentration, catalyst dosage and coexisting anions on degradation efficiency and kinetics of TC were investigated. Under optimal conditions (TC = 40 mg L-1, pH = 6.2, PS = 3.0 mM, catalyst = 0.1 g L-1), the kinetic reaction rate constant could reach 0.0264 min-1 in Fe2Mn1@BC-0.3SiO2/PS system, which was 12 times higher than that in the BC/PS system (0.00201 min-1). The electrochemical, X-ray diffractometer (XRD), Fourier transform infrared spectrum (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis showed that both metal oxides and oxygen-containing functional groups provide more active sites to activate PS. The redox cycle between Fe(II)/Fe(III) and Mn(II)/Mn(III)/Mn(IV) accelerated the electron transfer and sustained the catalytic activation of PS. Radical quenching experiments and electron spin resonance (ESR) measurements confirmed that surface sulfate radical (SO4•-) play a key role in TC degradation. Three possible degradation pathways of TC were proposed based on high-performance liquid chromatography coupled with high-resolution mass spectrometry (HPLC-HRMS) analysis, the toxicity of TC and its intermediates was analyzed by bioluminescence inhibition test. In addition to the enhanced catalytic performance, the presence of silica also improved the stability of the catalyst, as confirmed by cyclic experiment and metal ion leaching analysis. The Fe2Mn1@BC-0.3SiO2 catalyst, derived from low-cost metals and bio-waste materials, offer an environmentally friendly option to design and implement heterogenous catalyst system for pollutant removal in water.

Determination of multiple bisphenol analogues and their metabolites in human serum by liquid chromatography tandem mass spectrometry.

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 ß-D-glucuronide, BPA monosulfate, BPA bis-(ß-D-glucuronide) and BPS monosulfate) were detectable. The occurrence of BPA bis-(ß-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.

[Simultaneous determination of nine estrogens in bullfrogs using filtered solid phase extraction and ultra-performance liquid chromatography-tandem mass spectrometry].

Due to the harmful effects of estrogens and their prevalence in animal foods, accurate analysis of estrogen levels in animal foods is imperative in order to effectively assess food safety risks and ensure consumer safety. Therefore, a rapid and accurate method based on PRiME HLB solid phase extraction (SPE) cartridge purification and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed to determine nine estrogen residues in bullfrogs. The nine estrogens included estriol (E3), 17ß-estradiol (ß-E), 17α-estradiol (α-E), 17α-ethinylestradiol (EE2), estrone (EI), diethylstilbestrol (DES), dienestrol (DE), hexestrol (HEX), and dienestrol diacetate (DD). This study optimized the mobile phase system, extraction solvent, and SPE cartridges. Because estrogens present weak alkalinity, adding a small amount of alkaline substance to the mobile phase benefits estrogen ionization into the ionic state, eliminates the peak trailing phenomenon, and enhances the signal response of estrogens to improve sensitivity. Estrogens have one or more hydroxyl groups in their chemical structures. According to the principle of similar solubility, polar solvents are chosen as extraction solvents. Based on the complex matrix composition of meat samples, SPE is required for purification to reduce matrix effects. The liquid chromatographic conditions were optimized, and the 0.5 mmol/L ammonium fluoride aqueous solution-acetonitrile system as mobile phases showed better sensitivity than the ammonium acetate aqueous solution-acetonitrile system and the ammonia-acetonitrile system for the nine estrogens. When acetonitrile was used as the extraction solvent, the extraction rates of all nine estrogens exceeded those of methanol and ethyl acetate and increased by 15%-40%. By focusing on the matrix purification effect of four different SPE cartridges, the results showed that the matrix purification ability of the PRiME HLB cartridge outperformed that of the HLB, C18, and Silica SPE cartridges. After purification by the PRiME HLB cartridge, the recoveries of all compounds were in the range of 70%-125%, and the DD recovery was increased from 47% to 74%, whereas the HEX recovery was reduced from 180% to 123%. Therefore, the PRiME HLB SPE cartridge was selected as the cleanup material for this experiment. Finally, the sample was extracted using acetonitrile, purified by PRiME HLB SPE cartridge, and separated on a Waters Acquity UPLC BEH C18 column (100 mm×2.1 mm, 1.7 µm) with a mobile phase of 0.5 mmol/L ammonium fluoride aqueous acetonitrile solution at a flow rate of 0.3 mL/min. The detection was conducted in positive and negative ion switching mode (ESI+/ESI-) and multiple reaction monitoring (MRM) scanning, and it was quantified using a matrix-matched external standard method. Under the optimal experimental conditions, the linear ranges were 0.5-100.0 µg/L for E3, ß-E, α-E, EI, DE, HEX, and DD, and 1.0-100.0 µg/L for EE2 and DES. The nine estrogens showed good linearity in all linear ranges, with correlation coefficients of 0.9953-0.9994. The limits of detection were 0.17-0.33 µg/kg, and the limits of quantification were 0.5-1.0 µg/kg. The recoveries of the nine estrogens spiked at the three spiked levels of low (2.0 µg/kg), medium (10.0 µg/kg), and high (80.0 µg/kg) were 107.4%-125.3%, 67.0%-123.3%, and 65.1%-128.2%, respectively. The relative standard deviations were 1.9%-17.6%. The method established in this study was applied to detect nine estrogen residues in 50 commercially available bullfrog samples, and the results showed that HEX, EI, and DES were detected in few samples. The method is simple, rapid, sensitive, and reproducible, and can be used for the simultaneous, rapid and accurate determination of large quantities of samples.

[Determination of 4 chlorpromazine and promethazine and their metabolites in swine tissues by liquid chromatography-tandem mass spectrometry with isotope internal standard dilution technique].

OBJECTIVE: To establish a rapid, accurate and sensitive method by liquid chromatography-tandem mass spectrometry with isotope internal standard dilution technique for the determination of chlorpromazine and promethazine and their metabolites in swine tissues. METHODS: The swine tissues sample was extracted with acetonitrile and purified on MCX cartridge. The liquid chromatography separation was performed on an ACQUITY UFLC® HSS T3(100 mm×2.1 mm, 1.8 µm) with a linear gradient elution program of 0.1%(V/V) fomic acid-acetonitrile and 0.1%(V/V) formic acid-water solution as the mobile phase. The analytes were analyzed using ESI operating in the positive multiple reaction monitoring(MRM) mode. RESULTS: The limits of quantitation(LOQs) and limits of detection(LODs) for the target objects were 0.12-0.51 µg/kg and 0.04-0.17 µg/kg, respectively. The calibration curves were linear in range of 0.1-20.0 µg/L for chlorpromazine and promethazine, and 0.5-100.0 µg/L for their metabolites(chlorpromazine sulfoxide and isopropyl sulfoxide). The recoveries were between 90.8%-106.0%, and the relative standard deviations(RSDs) were between 1.9%-6.2%(n=6). CONCLUSION: The method is highly sensitive and accurate, and is suitable for the analysis of chlorpromazine and promethazine and their metabolites(chlorpromazine sulfoxide and isopropyl sulfoxide) in swine tissues.

[Adulteration identification of wheat flour in chestnut flour based on differences in mycotoxin contamination by liquid chromatography-tandem mass spectrometry].

An analytical method based on dispersive solid-phase extraction (d-SPE) and ultrafast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) was employed for the determination of 43 mycotoxins in chestnut flour and wheat flour. A total of 128 samples consisting of 48 chestnut samples and 80 wheat flour samples were collected randomly and subjected to analysis. Finally, five specific toxins were selected as markers to identify these two foodstuffs. Acetonitrile-water (84∶16, v/v) was used to extract mycotoxins from chestnut flour and wheat flour. After extraction, the supernatant was transferred to the d-SPE equipment, using which purification was performed with C18 and EMR-Lipid (lipid adsorbent). Chromatographic separation was carried out by gradient elution with eluent A (ESI+: 0.1% formic acid, ESI-: water) and eluent B (ESI+: methanol-acetonitrile (1∶1) containing 0.1% formic acid, ESI-: acetonitrile) on a BEH C18 column (100 mm×2.1 mm, 1.7 µm). Quantitative analysis was performed with the aid of matrix-matched curves. When establishing the method, the experimental matrix for optimization was designed by central-composite design based on the response surface methodology. Quadratic polynomial equations were deduced to describe the relationships between the responses and variables, and assess the interaction effects among the variables to acquire the true optimal conditions with less workload. Using the optimum experimental conditions, the accuracy of the proposed method was determined through three-level spiking tests, while the precision was evaluated in terms of the repeatability (six replications per level). Satisfactory precisions (RSDs≤7.5% in chestnut flour and RSDs≤9.3% in wheat flour) were achieved in all tested assays. The recoveries were also acceptable, and ranged from 72.4% to 109.4% for chestnut flour and from 70.7% to 112.9% for wheat flour. The matrix effects of mycotoxins were 48%-128% in wheat flour and 41%-112% in chestnut flour. The detectability of mycotoxins in the two matrices was assessed by spiking the blank extracts with various low concentrations, and determined as the lowest values that can produce chromatographic peaks at a signal-to-noise ratio (S/N) of 3∶1. The obtained limits of quantification varied from 0.10 µg/kg to 20 µg/kg (bongkrekic acid) in both investigated matrices. Satisfactory linearities were obtained, with correlation coefficients>0.9991 for all the analytes. After validation, the contamination status of the multiple mycotoxins was evaluated for various concentration ranges. Based on the obtained data, both wheat flour and chestnut flour were severely contaminated, with 17 mycotoxins detected in them. Particularly, chaetoglobosin A, ochratoxin B, and penicillic acid were only detected in chestnut flour, while 3-acetyl-deoxynivalenol, deoxynivalenol, and nivalenol were detected in wheat flour. Further, the positive rates and contamination concentrations of chaetoglobosin A, ochratoxin B, and penicillic acid were not significant; hence, they did not qualify as identification markers. On the other hand, the incidence of deoxynivalenol in wheat flour almost reached 100%, which is very significant. Finally, deoxynivalenol and its four derivatives (3-acetyl-deoxynivalenol, 15-acetyl-deoxynivalenol, deepoxy-deoxynivalenol, and nivalenol) were treated as adulteration markers for the two foodstuffs. To improve the reliability of the conclusion, all samples were re-tested using the first method prescribed by the National Food Safety Standard, i. e., GB 5009.111-2016. Ten chestnut flour samples were also randomly selected to prepare moldy samples under suitable environmental conditions for the growth of Fusarium, to verify the production and release of deoxynivalenol and its derivative mycotoxins under the extreme conditions. The distribution data for these mycotoxins were consistent with those obtained by d-SPE, confirming that the adulteration criterion is trustworthy. The established method is simple, rapid, sensitive, and accurate, and can effectively meet the requirements for the simultaneous determination of multiple mycotoxins in chestnut flour and wheat flour. Moreover, the adulteration results, which were obtained for natural contaminants (deoxynivalenol and its four derivatives), are less affected by humans and hence, much more accurate and reliable.

[Contamination status and the health risk evaluation of dietary exposure of quinolone and tetracycline antibiotics in animal derived foods in Ningbo City from 2018 to 2020].

OBJECTIVE: To investigate the dietary exposure of Ningbo residents to quinolones and tetracyclines antibiotics in animal derived foods, so as to estimate the health risk caused by the exposure. METHODS: Animal derived foods in Ningbo markets from 2018 to 2020 were collected and analyzed by ultra-fast liquid chromatography-tandem mass spectrometry. Based on the result of the measurements, median(M), P97.5, average and the maximum values of the data were obtained. Coupling the food intake data of residents in Zhejiang Province, an international point estimate model was applied to evaluate the health risk caused by the dietary exposure. RESULTS: Enrofloxacin, ciprofloxacin, ofloxacin, doxycycline, oxytetracycline were detected in freshwater fishes, cultured pseudosciaena crocea, freshwater shrimps, chicken, eggs and pork. The detection rates of enrofloxacin, ciprofloxacin, ofloxacin, doxycycline, oxytetracycline were 21.2%(77/363), 11.6%(42/363), 2.8%(10/363), 1.4%(5/363), 0.6%(2/363), respectively. The dietary exposure of adults and children from animal derived foods were in the range of 0.8-909.0 and 0.6-518.9 ng/(kg·d), respectively. The hazard quotient(HQ) values were in the range of 0.000030-0.17. CONCLUSION: Quinolone and tetracycline antibiotics such as enrofloxacin and oxytetracycline have no dietary health risk to the population.

[Dispersive solid-phase extraction combined with high-performance liquid chromatography for determination of seven anesthetics in aquatic products].

Nowadays, anesthetics are widely used in fishery production processes, such as fish breeding, surgery, and fresh aquatic product transportation. Because of the widespread application of anesthetic drugs in aquatic products, there is an increasing demand for the rapid and sensitive detection of anesthetic drugs in aquatic products. The complex aquatic product matrix contains a variety of interfering substances, such as proteins, fats, and phospholipids, along with anesthetic drug residues at very low concentrations; therefore, it is necessary to adopt appropriate pretreatment methods for improving the sensitivity of detection. In this study, a dispersive solid-phase extraction (DSPE) method, combined with high-performance liquid chromatography, was established for the simultaneous detection of seven anesthetic drugs in aquatic products, viz. procaine, oxybuprocaine, tricaine, eugenol, methyl eugenol, isoeugenol, and methyl isoeugenol. For the DSPE step, pretreatment conditions, such as extraction solvent, extraction time, adsorbent amount, and DMSO dosage, were optimized. Sample pretreatment is a three-step process. First, in ultrasound-assisted extraction, 2.0 g samples were extracted using 10.0 mL 1.0% formic acid in acetonitrile under ultrasound conditions for 10 min. Then, DSPE was performed with mixed adsorbents: the solvent extracts were cleaned using 20 mg poly(styrene-glycidylmethacrylate) microspheres (PS-GMA), 50 mg primary secondary amines (PSA), and 10 mg C18, followed by separation by centrifugation. Finally, DMSO-assisted concentration was applied: the organic layer was collected and was dried at 40 ℃ in a N2 stream with 100 µL DMSO. Water was added to the residue to obtain a final volume of 1.0 mL for HPLC analysis. The seven anesthetic drugs were separated on a Welch welchrom C18 column (250 mm×4.6 mm, 5 µm) by gradient elution using methanol and 0.05% formic acid in 5 mmol/L ammonium acetate aqueous solution as mobile phases. The detection wavelengths were 235, 260, and 290 nm. Two matrix matching standard curves for fish and shrimp were applied for quantitative analysis. Under optimized conditions, the seven target anesthetics showed good linear relationships in their respective concentration ranges (R2>0.999), with the limit of detection (LOD) ranging from 0.011 to 0.043 mg/kg. In fish samples, the mean recoveries obtained at three concentration levels were between 79.7% and 109%, with relative standard deviations (RSDs) being less than 7.2%. In shrimp samples, mean recoveries were 78.0%-99.9%, with RSDs being less than 8.3%. This simple, rapid, accurate, and sensitive method can be applied to the detection of three kinds of aminobenzoic acid esters and four kinds of eugenol anesthetic drugs in aquatic products.

Cationic polyacrylamide (CPAM) enhanced pressurized vertical electro-osmotic dewatering of activated sludge.

Pressurized vertical electro-osmotic dewatering (PVEOD) has been regarded as a feasible method to achieve sludge deep-dewatering, but the dewatering efficiency is still challenged by high electric resistance. This study employed cationic polyacrylamide (CPAM) as a skeleton builder to enhance electro-osmotic flow in PVEOD. The sludge dewatering efficiency and synergistic effect of CPAM and PVEOD were elucidated. The sludge morphology, surface property, extracellular polymeric substances (EPS) destruction and migration, spatial distributions of proteins and polysaccharides, and current changes were investigated. After the addition of optimal CPAM dose, the sludge formed a uniform and porous structure that provided water channels and enhanced electric transport, thus promoting EPS destruction. The sludge moisture content (MC) analysis indicated the more liberation of bound water due to EPS destruction. Besides, the re-flocculation of disintegrated sludge flocs improved the sludge filtration and thus dewaterability. Instantaneous energy consumption (Et,0.5) was optimized and two-step synergistic mechanism was thus proposed. These findings indicated that the combination of CPAM and PVEOD is a promising strategy to broaden the scope of industrial application of sludge deep-dewatering.

[Determination of fipronil and its metabolites in eggs using dispersive- solid phase extraction and gas chromatography-tandem mass spectrometry].

OBJECTIVE: To develop a method for determination of fipronil and its metabolites in eggs by gas chromatography-tandem mass spectrometry(GC-MS/MS)cleaned with dispersive-solid phase extraction(D-SPE). METHODS: Orthogonal array design with OA16(4~4) matrices was used to optimize the efficiency of D-SPE. The targets were extracted from samples with acetonitrile, and followed by D-SPE cleanup. The extracts were analyzed by GC-MS/MS, and quantified by internal standard method with matrix correction. RESULTS: The calibration curves showed good linearity in the range of 1.0-250.0 µg/L. The correlation coefficients were larger than 0.99.The average recoveries spiked in eggs at the levels of 2 µg/kg, 4 µg/kg and 20 µg/kg were between 87.1% and 125.0%(n=6), and the relative standard deviations were less than 10%. The limits of determination were between 0.1 and 0.4 µg/kg, and the limits of quantitation were between 0.3 and 1.2 µg/kg. CONCLUSION: The method possesses low background, high sensitivity. It can be applied to determine the residues of fipronil and its metabolites in eggs.

Investigation on the occurrence and contamination of multi-mycotoxin in chestnut and jujube (red date).

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.

[Determination of trace low molecular mass aldehydes in air by ultra-fast liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To establish a rapid and accurate method for the determination of trace acetaldehyde, acrolein, methacrylaldehyde, crotonaldehyde in the air by ultra-fast liquid chromatography-tandem mass spectrometry(UFLC-MS/MS). METHODS: The air sample was concentrated and derivatived by 3-methyl-2(3 H)-benzothiazolonhydrazone(MBTH), and the effect of derivative conditions including the concentration of MBTH, the pH, the derivative time and temperature was investigated. The stability of derivatives, the cracking mechanism of mass spectrometry, the matrix effect of the method and air sampling efficiency were studied. The chromatographic separation was carried out on a Shim-pack XR-ODS II column(100 mm×2. 0 mm, 2. 2 µm) by using water/methanol solution as the mobile phase with the gradient elution. Detection was performed in positive multi-reaction monitoring(MRM) mode for quantification by using external standard method. RESULTS: The four analytes showed good linear relationship within the range of 1. 00-100 µg/L(calculated by aldehyde) with a correlation coefficient r≥0. 9990. The limits of quantitation(LOQs) of the method(concentrated with 10 L air) were 0. 5 µg/m~3 in air, for acetaldehyde, acrolein, methacrylaldehyde, crotonaldehyde. The recoveries of the method were 90. 6%-97. 8% at the three spiked levels, and the relative standard deviations(RSDs) were between 1. 9%-6. 4%(n=6), the average sampling efficiency was between 91. 0%-97. 1%. CONCLUSION: The developed method is simple, less interference and specificity, and is suitable for the simultaneous rapid determination of trace acetaldehyde, acrolein, methacrylaldehyde, crotonaldehyde in air of work place.

[Contamination status and the evaluation of dietary exposure of marine biotoxins in seafood in Ningbo City in 2017-2019].

OBJECTIVE: Ultra-fast liquid chromatography-tandem mass spectrometry method was developed for the analysis of contamination degree of biotoxins in seafood in Ningbo City from 2017 to 2019 and the assessment of dietary exposure was conducted. METHODS: Samples were extracted and purified with optimized pretreatment process and then injected for analysis. According to the result of the measurements, an international point estimate model was used to evaluate the dietary exposure of the population. RESULTS: For tetrodotoxin and 16 shellfish toxins monitored routinely, gonyautoxin5(GTX5), tetrodotoxin and homo-yessotoxin(hYTX) had higher detection rate, other toxins including okadaic acid(OA), dinophysistoxin1(DTX1), decarbamoyl gonyautoxin2(dcGTX2) and decarbamoyl gonyautoxin3(dcGTX3) were detected sporadically. The detection rates of TTX、GTX and hYTX were 27%, 52% and 12%, respectively. The concentration ranges of TTX, GTX and hYTX in polluted samples were 0. 003-0. 535, 0. 008-0. 189 and 0. 032-0. 110 mg/kg. The exposure risk indices(ERI) of TTX, GTX5, hYTX, dcGTX2 and dcGTX3 were 2. 5, 0. 026, 0. 0080, 0. 79 and 0. 32, respectively. CONCLUSION: Marine biotoxins have a lower dietary health risk to the population. It is must be given great attention that in the season of toxic red tide, the detection rates of higher toxic toxins, dcGTX2 and dcGTX3 increased significantly with high risks to human. Moreover, the dietary health risk of tetrodotoxin in routine surveillance in 2019 was higher.

Manganese doped iron-carbon composite for synergistic persulfate activation: Reactivity, stability, and mechanism.

The heterogeneous catalytic process has been under development for aqueous pollutant degradation, yet electron transfer efficiency often limits the effectiveness of catalytic reactions. In this study, a novel composite material, manganese doped iron-carbon (Mn-Fe-C), was tailor designed to promote the catalytic electron transfer. The Mn-Fe-C composite, synthesized via a facile carbothermal reduction method, was characterized and evaluated for its performance to activate persulfate (PS) and degrade Rhodamine Blue (RhB) dye under different pH, catalyst dosages, PS dosages, and pollutant concentrations. Electron spin resonance, along with quenching results by ethanol, tert-butanol, phenol, nitrobenzene and benzoquinone, indicated that surface bounded SO4•- was the main contributor for RhB degradation, while the roles of aqueous SO4•- and •OH were very minor. Through characterization by XRD, XPS and FTIR analysis, it was determined that the electron transfer during activation of PS was accelerated by the oxygen functional groups on catalyst surface and the promoted redox cycle of Fe3+ and Fe2+ by Mn. Finally, the Mn-Fe-C composite catalyst exhibited an excellent reusability and stability with negligible leached Fe and Mn ions in solutions. Results of this study provide a promising design for heterogeneous catalysts that can effectively activate PS to remove organic pollutants from water at circumneutral pH conditions.

[Ultrasonic assisted-dispersive solid-phase extraction for rapid enrichment of N-nitrosodimethylamine in water].

OBJECTIVE: a novel and rapid analytical method was established for the extraction of N-nitrosodimethylamine in large-volume water samples. METHODS: Pretreatment was on the basis of ultrasonic-assisted-dispersed solid phase extraction. Coco housing activated carbon was incorporated into the water samples, and the rapid enrichment of N-nitrosodimethylamine was realized by implementing ultrasonic-assisted dispersion. After that, the suspension was filtered by suction, and the residue was eluted by dichloromethane. The eluate was collected and then concentrated to dry using rotary evaporation. Ultra-high performance liquid chromatography tandem mass spectrometer, which equipped with atmospheric pressure chemical ionization source was employed for determination under the multiple reaction monitoring mode. RESULTS: Limit of detection and quantification for N-nitrosodimethylamine in 500 mL water was 2. 0 ng/mL and 6. 0 ng/mL, respectively. Throughout the validation, good linearity with R~2>0. 999 were achieved with the range from 0. 5 ng/mL to 150. 0 ng/mL. Satisfactory recovery(95. 7%-100. 8%) and inter-day reproducibility(<4. 2%) were obtained by three-level spiking experiments in different water matrices. Finally, the established method was applied for analysis of 48 real samples, the detectable concentrations of positive samples were in the range of <2. 0 ng/L to 14. 4 ng/L. CONCLUSION: Compared with the traditional solid-phase extraction method, this method ology showed the characteristics of rapid and more efficient, and could save at least 50% of the pretreatment time. Meanwhile, the result of method ology validation were satisfactory.

Fabrication of benzenesulfonic acid groups modified magnetic microspheres as an MSPE adsorbent for fast determination of paraquat and diquat in human urine combined with UPLC-HRMS.

In this study, novel benzenesulfonic acid groups modified magnetic microspheres (Fe3O4@SiO2@poly(4-VB)) were synthesized and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectrometry (FTIR), and vibrating sample magnetometer (VSM). The as-prepared Fe3O4@SiO2@poly(4-VB) was employed as a magnetic-phase extraction (MSPE) adsorbent for rapid determination of paraquat (PQ) and diquat (DQ) in human urine samples coupled with ultra-high performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS). Moreover, this paper had expounded systematically the mass spectrum cracking mechanisms of PQ and DQ. And a zwitterionic functionalized SIELC Obelisc R column was employed for separation and retention of the above two polar herbicides using 50 mmol/L ammonium formate (pH = 3.7)-acetonitrile as the mobile phase. Besides, the adsorption and desorption conditions of Fe3O4@SiO2@poly(4-VB) toward PQ and DQ were optimized in spiking urine samples to obtain the best adsorption and desorption efficiencies. And the adsorption mechanisms of Fe3O4@SiO2@poly(4-VB) toward PQ and DQ referred to synergetic effect of electrostatic attraction and π-π interaction. Under the optimal conditions, the inter-day and intra-day spiking recoveries of the proposed method were in the range of 86.7-109.9% with RSDs less than 10%. The limits of detection (LODs) were obtained by spiking in blank urine samples at a series of low concentrations and were found to be 0.12 µg/L and 0.14 µg/L for PQ and DQ, respectively, which were lower than the comparing literatures. The developed analytical method was proven to be simple, rapid, sensitive, and accurate for clinical poisoning analysis.

[Determination of 25-hydroxyl vitamin D in serum by isotope dilution ultra-fast liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To establish a rapid and accurate method for determination of 25-hydroxyl vitamin D2, 25-hydroxyl vitamin D3 and 3-epi-25-hydroxyl vitamin D3 in serum by isotope dilution ultra-fast liquid chromatography-tandem mass spectrometry(UFLC-MS/MS). METHODS: The serum sample was extracted by nhexane after methanol/acetonitrile precipitation protein, and then the extract was concentrated by nitrogen and volumed with the primary mobile phase. The chromatographic separation was carried out on a Phenomenex Kinetex F5 column(2. 1 mm × 150 mm, 1. 7 µm) by using 0. 1%(V/V) formic acid and 0. 1%(V/V) formic acid/methanol solution as the mobile phase with the gradient elution. Detection was performed in positive multi-reaction monitoring(MRM) mode with the isotope internal labeling method for quantification. RESULTS: The baseline separation was obtained within 6 min for the epimer 25-hydroxyl vitamin D3 and 3-epi-25-hydroxyl vitamin D3, and the accurate qualification was obtained for the simultaneous determination of 25-hydroxyl vitamin D2, 25-hydroxyl vitamin D3 and 3-epi-25-hydroxyl vitamin D3. The three analytes showed good linear relationship within the range of 0. 5-50. 0 µg/L with a correlation coefficient r >0. 9995. The limits of detection(LODs) and the limits of quantitation(LOQs) of the method were 0. 15 µg/L and 0. 5 µg/L, respectively. The recoveries of the method were84. 3%-109. 0%(n = 11) at the three spiked levels of 1. 0, 10. 0 and 30. 0 µg/L, and the relative standard deviations(RSDs) were between 0. 8%-6. 8%. At the same time, the certified standard reference materials(SRM) of the America National Institute of Standards and Technology(NIST) Level 1, Level 2, Level 3 and Level 4(SRM 972 a)were used as the quality control samples for verification, the relative deviations of the measurement result were less than 5% compared with the reference values. CONCLUSION: The developed method has the characteristics of simplicity, rapidity, sensitivity and accuracy, and is suitable for the simultaneous rapid determination of 25-hydroxyl vitamin D2, 25-hydroxyl vitamin D3 and 3-epi-25-hydroxyl vitamin D3 in serum.

Contamination status of bisphenol A and its analogues (bisphenol S, F and B) in foodstuffs and the implications for dietary exposure on adult residents in Zhejiang Province.

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.

[Determination of residual glyphosate and aminomethylphosphonic acid in wheat flour and oats samples by non-derivatization method based on ultra-performance liquid chromatography-high resolution mass spectrometry].

A rapid and accurate analysis method based on ultra-performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS) was developed for the determination of residual glyphosate (GLY) and aminomethylphosphonic acid (AMPA) in wheat flour and oats samples. The wheat flour and oats samples were firstly subjected to vortex and ultrasound extraction; then, the extract solution was purified by MCX solid-phase extraction (SPE) cartridges as well as protein precipitation using acetonitrile. The chromatographic separation was carried out on a Dikma Polyamino HILIC column (150 mm×2.0 mm, 5 µm) by linear gradient elution procedure using 5 mmol/L ammonium acetate in water (pH=10.5) and acetonitrile as the elution solvent. An electrospray ion source in negative mode and parallel reaction monitor (PRM) mode was used for quantification by the internal standard method. The instrument conditions for liquid chromatography (LC) and HRMS, and the sample pretreatment conditions for GLY and its metabolite AMPA were systematically optimized. In addition, the matrix effect and injection system residue were investigated, and a comparison of different analytical methods was carried out. The results indicated that GLY and AMPA showed good linearities in the range of 5.0-100.0 µg/L with coefficients (R2) higher than 0.999. The limits of detection (LODs) were found to be 0.005 and 0.05 mg/kg for GLY and AMPA, respectively. The recoveries of GLY and AMPA in the wheat flour and oats samples were in the range of 93.8%-115% and 89.8%-110% at the spiked levels of 0.1, 0.5, and 2.0 mg/kg, respectively, while the relative standard deviations (RSDs) were all less than 10%. The results of the matrix effect test revealed that the matrix inhibition effect could be reduced by using an isotopic internal standard with the matrix effect parameter |η|<3%. Moreover, the injection system residue was effectively controlled with a residual level of less than 1.0%. A comparison of the developed method with the reported derivatization method indicated little difference, with RSDs of 2.19% and 3.07% to the assigned value, respectively. The established analytical method was used for the Food Analysis Performance Assessment Scheme (FAPAS) proficiency test (No. 09122, GLY in oats), and the results were satisfactory with a z value of 0.2. Moreover, the result obtained using this method was very closed to the assigned value of the FAPAS QC sample, with a recovery of 102.2% (No. T09119QC, GLY in wheat flour). The proposed method is fast, simple, sensitive, and accurate, and it can be applied for the daily monitoring of GLY and its metabolite AMPA in wheat flour and oats samples.