采用在湿米粉及其原料米和米浆中分别接入不同浓度(103、105和107 cfu/mL)椰毒假单胞菌酵米面亚种(简称"椰毒假单胞菌"),在最佳产毒温度(26℃)和最佳生长温度(36℃)中培养并检测毒素米酵菌酸含量变化等技术,研究分析了椰毒假单胞菌在三种食物基质中的生长产毒规律以及相关风险.结果表明:椰毒假单胞菌产米酵菌酸的量与食物基质中椰毒假单胞菌量呈正相关,与食物性状、含水量等有较大相关性;相同接菌量、培养温度和时间下,湿米粉中米酵菌酸含量高于原料米和米浆(最高约5000多倍);湿米粉和原料米分别接菌105 cfu/mL、26℃和36℃培养,培养48 h时湿米粉中米酵菌酸含量可高达27 mg/kg,风险较高,原料米培养期间(35d)米酵菌酸含量约在0.7～16μg/kg,风险较低.研究提示应从原料、生产、储运、经营和消费全链条来加强防控湿米粉被椰毒假单胞菌污染产毒.

Functionalized magnetic nanoporous carbon derived from banana peel was synthesized through carbonization, porogenesis, carboxylation and magnetization using banana peel and was successfully used as a magnetic solid phase extraction (MSPE) material for the enrichment of six bisphenols (BPs) from beverage and water samples. After the optimization of MSPE process, the enrichment factors of six target analytes were in the range of 74-112 for water samples, and 15-22 for beverage samples. Then, high-performance liquid chromatography-quadrupole-Orbitrap high-resolution mass spectrometry (HPLC-Q Orbitrap-HRMS) was used for the separation and determination of the target analytes. Results showed that the extraction recoveries for 6 BPs were in the range of 71.9-108.4% with an RSD of 2.5-7.5% (n = 6). These results demonstrated that the as-prepared material could efficiently enrich some aromatic compounds and the proposed method is reliable and robust for the determination of BPs in water and beverage samples.

An analytical method based on PRiME (process, robustness, improvements, matrix effects, ease of use) HLB purification followed by the ultra-high liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) detection has been developed for the determination aflatoxin B1, B2, G1 and G2 and bongkrekic acid in rice and noodle products. Five toxins were separated on a Waters BEH C18 column by gradient elution, scanned by ESI+ and ESI- dynamic switching and detected with MRM mode. LOD, LOQ, matrix effects, accuracy and precision of the developed method were investigated. Under the optimal sample pretreatment conditions, high sensitivity (LOQs: 0.20-0.40 mu g/kg), good recoveries (80.5%-106.6%) and acceptable precision (2.4%-7.2%) were obtained for the analysis of the four aflatoxins and bongkrekic acid. This method was successfully applied to the analysis of rice and noodle products, demonstrating its applicability and suitability for the routine analysis of aflatoxins and bongkrekic acid in rice and noodle products.

The fragmentation pathway of H2PO2- in MS was obtained by Orbitrap HRMS and the reverse confirmation was carried out by the neutral loss detection experiment. The results showed that H2PO2- with even electron ion would produce the neutral loss of 2H and form a new even electron ion with a pair of lone-pair electrons. Based on this, a LC-MS/MS method was developed for the determination of H2PO2- in flour and flour products. The H2PO2- was separated on an Acclaim Trinity P1 composite ion exchange column, and then detected by MS/MS under MRM mode. Finally, the developed method was validated in terms of the linearity, selectivity, accuracy, precision and matrix effect. The method showed a good linearity (R-2>0.999) in the concentration range of 50 similar to 1500 mu g/L. The LOD and LOQ for H2PO2- were 10.0 mg/kg and 30.0 mg/kg, respectively. The average recoveries and RSDs (n = 6) were 93.0%similar to 102.9% and 2.6 similar to 5.6%, respectively.

米酵菌酸(BA)具有剧烈毒性,为了研究BA经紫外照射后的降解效果,以BA-甲醇水为研究模型,考察紫外照射强度、BA初始浓度、液层厚度对BA的降解效果,并对其降解曲线和降解方程进行拟合.结果表明,紫外光照射能有效降解BA,且降解过程符合一级动力学方程;紫外强度越强、BA初始越低、液层厚度越薄,BA的降解速率越快.在紫外强度为187μW/cm2,初始浓度为2.5μg/mL,厚度为2 mm时,2 h后的降解率达到96.82％.用SPSS软件建立各影响因素与光解速率常数的单独模型并进行线性回归,紫外照射强度、BA初始浓度、液层厚度三个影响因素的模型拟合度分别为0.9540、0.9347、0.9643.在此基础上,用多元线性回归方法建立紫外照射强度(X1)、BA初始浓度(X2)、液层厚度(X3)与紫外降解速率常数k(Y)的综合模型,模型的拟合度为0.972,回归方程显著.本研究结果为紫外降解BA提供了理论基础.

Perchlorate (ClO4-), a type of contaminant with high diffusivity and durability, has been widely detected in water and foodstuffs, arousing a global concern. It can interfere with normal function of the human thyroid gland, affecting human health. Therefore, determination of perchlorate in water and foodstuffs, and removal from water are important. This review focuses on the occurrence of perchlorate, mainly in water and foodstuffs, and provides an overview of analytical methods for determination of perchlorate over the last two decades. In addition, merits and drawbacks of the various methods have been considered. This review also highlights the most commonly used approaches for removal of perchlorate from water. Finally, current trends and future perspectives in determination of perchlorate and removal from water are proposed. This review provided a comprehensive understanding of perchlorate occurrence and its removal from water, and had practical significance in reducing the harm of perchlorate to human.

The existing extraction and detection methods of bongkrekic acid (BKA) and isobongkrekic acid (IBKA) are complex, time-consuming and solvent-consuming. In this work, a simple and fast pre-concentration procedure based on Fe3O4/HNTs was developed for the determination of BKA and IBKA in rice noodles using HPLC-Orbitrap HRMS. The structure and morphology of Fe3O4/HNTs was characterized by means of XRD, SEM, FT-IR and VSM. Parameters affecting the extraction efficiency including adsorbent amount, pH, extraction time, type and volume of eluent were investigated by employing the response surface method. Results indicated that the proposed method had favorable linearity in the concentration range of 2-200 μg/L with a correlation coefficient >0.998. Method LOD and LOQ were 0.3 μg/kg and 1.0 μg/kg, respectively. Finally, the method was successfully applied to determine BKA and IBKA in rice noodle samples from southern China with recoveries ranging from 79.8% to 102.6% and relative standard deviation (RSD) of 4.2%-7.1%.

An effective method was developed for the simultaneous determination of 4 kinds of antioxidants and 8 kinds of the ultraviolet absorbers in plastic packaging baked foods by QuEChERS enhanced matix removal-lipid (EMR-Lipid) combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) . The samples were extracted by acetonitrile-acetone (1 : 1 , V/V) . The 12 targets were separated on a Waters BEH C-18 column by gradient elution with methanol-10mmol/L ammonium acetate as mobile phase , ionized with positive and negative electrospray ionization (ESI+/-), detected under multiple reaction monitoring mode (MRM), and quantified with external standard method. The result showed that the 12 kinds of analytes presented favorable linearity in the respective linear range , with correlation coefficients (R-2) of more than 0.9978. The method detection limits (S/N = 3) were in the range of 5. 0 - 10. 0 mu g/kg, except for the Antioxidant 2246 was 150.0 mu g/kg. The average recoveries (n=6) ranged from 80.3% to 118.5%, with intra-day relative standard deviations (RSD, n=6) of 1.7%-9.8% and inter-day RSD (n=5) of 4.5%-9.9%. The developed method had simple pre-treatment procedure, satisfactory purification and sensitivity, and was suitable for the simultaneous determination of antioxidants and ultraviolet absorbers in plastic packaging baked foods.

The present work reported a high-throughput strategy for the analysis of 21 perfluorinated compounds (PFCs) in drinking water, tap water, river water and plant effluent from southern China by supramolecular solvent (SUPARS) vortex-mixed microextraction combined with high performance liquid chromatography-Orbitrap high resolution mass spectrometry (HPLC-Orbitrap HRMS). The SUPRAS without heating assistance is less solvent-consumption, meeting the requirements for green environmental protection and sustainable development. Parameters in the microextraction such as volume of dodecanol and tetrahydrofuran (THF), vortexing extraction and centrifugation time, salt concentration were investigated. The optimal extraction conditions were 250 μL of undecanol, 1.0 mL of THF and 20.0% (w/v, 4 g) NaCl. Under the optimum conditions, method limit of detection and method limit of quantitation in the ranges of 0.01-0.08 μg/L and 0.03-0.25 μg/L, good recoveries (72.5-117.8%) and intra-day precision (1.1-11.2%, n = 6), high enrichment factors (48-78) were obtained. The developed method was successfully applied for analysis of PFCs in 13 drinking water, tap water, river water and plant effluent samples collected from southern China. Perfluorobutane sulfonic acid was detected in one river water with concentration of 0.48 μg/L and 1H,1H,2H,2H-Perfluorooctane sulfonic acid was detected in one river water and two plant effluent samples with concentrations in the range of 0.14-0.67 μg/L.

Ethyl carbamate (EC) and N-nitrosoamines (NAs) are toxic contaminants which can be typically formed in fermented alcoholic beverages. In the present work, a novel approach for simultaneous analysis of EC and NAs in beer and yellow rice wine based on ice-bath assisted sodium hydroxide purification and GC-MS/MS was firstly established. Samples were extracted with acetonitrile-ethyl acetate after addition of internal standards. The extraction solution system was purified by sodium hydroxide solid under ice-bath. After concentration, target analyzes were separated on a HP-INNOWAX quartz capillary column and determined under dynamic multiple reactions monitoring mode of MS/MS. The limits of detection and quantification (LOD and LOQ), matrix effect, recovery and precision of the method were evaluated. Results were linear in the concentration range 2-200 mu g/L for all analyzes of interest, with regression coefficients higher than 0.999. LODs and LOQs were in the ranges of 0.1-0.5 mu g/kg and 0.5-1.5 mu g/kg, respectively. The mean recoveries M three spiked levels were between 81.5% and 121.0%. The intra- and inter-day precisions were in the ranges of 2.2-9.4% and 1.6-7.9%, respectively. The validated method was successfully applied to determine thirteen targets in commercial beer and yellow rice wine. EC was detected in all beers and yellow rice wines with the concentrations ranging from 1.18 to 22.90 mu g/ L. Results indicated wide EC contamination and confirmed its urgency for monitoring EC in fermented alcoholic beverages.

An ultra-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous analysis of 4(5)-methylimidazole (4-MI) and acrylamide (AA) in biscuit products. The samples were extracted with methanol followed by dispersive primary secondary amine clean-up. The analytes were separated by reverse phase liquid chromatography, detected by tandem mass spectrometry in multiple reaction monitoring (MRM) mode, and quantified using internal standards of deuterium-labeled d(6)-4-MI and d(3)-AA. The method was validated with respect to linearity, limits of quantification, precision, trueness and measurement uncertainty. Good linearity (R-2 > 0.999) for all calibration curves was obtained. The mean recoveries were from 93 to 10B% for the analytes, with coefficients of variation less than 9.2% being observed. The limits of quantification of 5 and 10 ng/g were also achieved for 4-MI and AA, respectively. The expanded measurement uncertainty for these compounds was below 19%. Finally, the method has been applied to the analysis of 17 commercial biscuit samples, revealing that the wide presence of 4-MI and AA in biscuit products. The proposed method proved to be a reliable and sensitive tool for 4-MI and AA measurements in biscuit products.

A sensitive analytical method for the monitoring 2-methylimidazole and 4-methylimidazole (2-MI and 4-MI) is desirable due to their carcinogenic property. Here, we propose a highly sensitive method basing on the combination of solid-phase extraction and dispersive liquid-liquid microextraction techniques followed by high-performance liquid chromatography to simultaneously determine 2-MI and 4-MI in beverages. Dansyl chloride was used as a derivatizing reagent. Microextraction parameters were optimized by Plackett-Burman design and response surface methodology. Results show that derivatization led to significant improvements in chromatographic behavior for 2-MI and 4-MI due to increased hydrophobicity. The method shows good linearity (R-2 >= 0.9985), satisfactory precision (%RSD <= 8.3%) and low limit of quantification (20 ng/mL), and was successfully applied to determine 2-MI and 4-MI in carbonated drinks, beers and energy drinks, achieving satisfactory recoveries (85-101%). This method provides a potential for routine analysis of 2-MI and 4-MI at the nanogram per milliliter level in beverages.

The presence of potential carcinogen 4(5)-Methylimidazole (4-Mel) in foods causes much concern, stressing the need of a sensitive determination means. Here, we proposed a high-sensitivity method to determine 4-Mel in biscuits using dansyl chloride derivatization and disperse liquid-liquid micro-extraction (DLLME) followed by a liquid chromatography-ion trap mass spectrometry (LC-IT-MS) analysis. This developed method was subsequently compared to the solid phase extraction combining with liquid chromatography-triple quadrupole mass spectrometry (SPE-LC-QqQ-MS) method. The optimized derivatization conditions were 30 degrees C and 10 min. Results suggested that the column retention time (RT) was significantly extended, and the MS signal response of 4-Mel-dansyl derivative was also amplified. The developed DLLME-LC-IT-MS method in 4-Mel determination provided satisfactory linearity in a range of 0.5-300 ngimL (R-2 > 0.9991), inter-day accuracy (87-102%) and precision (%RSD <= 13.6%) with the quantification limit of 0.2 ng/mL, which obtained similar results comparing to the conventional SPE-LC-QqQ-MS method. (C) 2019 Elsevier B.V. All rights reserved.

The presence of 2-acetyl-4(5)-(1,2,3,4-tetrahydroxybutyl)-imidazole (THI) in beverages has raised several concerns regarding its toxicity to humans. The sample preparation and detection of THI in complex matrices is challenging owing to its high water solubility. Here we reported a rapid sample preparation method based on dispersive micro-solid phase extraction (D-iu-SPE) using polymer cation exchange sorbent as sorbent for the extraction of THI from beverage samples. THI was detected by high performance anion exchange chromatography-pulsed amperometric detector (HPAEC-PAD) and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The experimental parameters of D-p-SPE on extraction efficiency were carefully optimized. Under the optimized conditions, high recoveries (83.4-96.1%) and good reproducibility (% RSD <= 8.7%) were obtained using D-mu-SPE-HPAEC-PAD and D-mu-SPE-HPLC-MS/MS. Limit of quantification was 75 ng/mL for HPAEC-PAD and 5 ng/mL for HPLC-MS/MS. This work proves the potential application the newly developed method for the quantification of THI in beverages containing caramel color.

A new magnetic sorbent named as ferromagnetic fluorinated graphene (FG@Fe3O4) was prepared for extraction and enrichment of 10 kinds of fluorine-containing pesticides in tea soups , which were then detected by gas chromatography tandem triple quadrupole mass spectrometer (GC-MS/MS). The transfer rate of fluorine-containing was also investigated. Due to the pi electrons and F atoms , FG@Fe3O4 could form pi-pi conjugation and fluorous-fluorous interaction with fluorine-containing pesticides, and the magnetic sorbent displayed excellent adsorption performance for 10 kinds of fluorine-containing pesticides. Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry and vibrating sample magnetometer were used to characterize the sorbents. The main parameters, such as sorbent amount, desorption solvent, extraction time were investigated. The adsorption properties of different sorbents and the recycle times of FG@Fe3O4 were also investigated. Under the optimum conditions , the linear relations were good in the corresponding concentration range with the correlation coefficients of more than 0. 998. The method limits of detection (S/N= 3) and method limits of quantitation (S/N=10) ranged from 0. 3 mu g/kg to 6. 0 mu g/kg and 1.0 mu g/kg to 20. 0 mu g/kg, respectively. The average recoveries ranged from 71. 2% to 108. 4% and the intra-day precisions were 2. 6% - 8. 7% at three standard spiked levels. This developed method was successfully applied for the detection of 10 tea soup samples , among which flubendiamide was detected in 2 samples, flufenoxuron was detected in 2 samples , and triflumizole was detected in one sample. The transfer rate of different fluorine-containing pesticide from teas to infusion was different.

4(5)-Methylimidazole (4(5)-MI) is a potential carcinogen with low molecule weight, highly polarity, and weak basicity. The traditional way to extract and clean-up 4(5)-MI in soy sauce using solid phase extraction is tedious and time consuming. Here we proposed a method for the determination of 4(5)-MI in soy sauce by combining a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction with liquid chromatography-mass spectrometry analysis. The impacts of solution pH, water addition, and cleanup procedure on 4(5)-MI extraction efficiency were studied. An optimized sample preparation approach involved a single step liquid-liquid extraction between acetonitrile and soy sauce under alkaline conditions, followed by primary and secondary amine clean-up. The analytical method was validated with soy sauce at three spiking levels (10, 50, 500 ng/g). The method recovery (96.2-107%) and intra-day/inter-day precision (4.1-8.4%/6.9-11.7%) were satisfactory. The method quantification limit was 10 ng/g. The developed method was successfully applied for the determination of 4(5)-MI in fourteen commercial soy sauces from local markets. The results obtained in this work suggests that the method is suitable for the analysis of 4(5)-MI at low concentrations in high-salting and protein-containing soy sauce matrix.

The determination of carcinogenic 4(5)-methylimidazole (4-MeI) in complex matrices at trace levels is a challenge because of its higher polarity and weaker column retention capability. Here, we proposed a novel method for the quantification of 4-MeI in various foods and beverages using modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The evaluated QuEChERS extraction with LC-MS/MS method showed excellent linearly (1-200 mu g/L, with correlation coefficient (R-2) > 0.999), trueness (91-113%), and precision (relative standard deviation (RSD) <= 12.3%), but low matrix effect (92-108%) for cola, tea, beer, coffee beverage, bread, biscuit and instant coffee. The expanded measurement uncertainty was less than 34.4% at 95% confidence level. The proposed method can be successfully applied to determine 4-MeI in 28 commercial foods and beverages purchased from local market. Therefore, we believe this method is likely to provide a potential for 4-MeI determination in practical application.

The present work presents a novel and rapid analytical method for the simultaneous analysis of bisphenol A (BPA), bisphenol B (BPB), bisphenol F (BPF) and bisphenol S (BPS) in edible oil based on dispersive micro solid phase extraction (DMSPE) for the first time followed by isotope dilution-ultra high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The edible oil sample was dispersed by n-hexane and extracted with ammoniated methanol-water solution. Then the target analytes were dispersedly absorbed using the polymer anion exchange (PAX) as the sorbent and eluted by acidic methanol. After that, four bisphenols were separated on a C18 column by gradient elution with methanol and 0.05% ammonium hydroxide in water as mobile phase, detected by MS/MS under multiple reactions monitoring (MRM) mode and quantified by internal standard method. The PAX amounts, adsorption time, concentrations of formic acid in the elution solvent and volume of elution solvent for the DMSPE technique were optimized. The limit of detection and quantitation (LOD and LOQ), matrix effect, recovery and precision of the developed method were investigated. Results indicated that BPS and the rest three bisphenols displayed excellent linearity in the concentration ranges of 0.1-50μg/L and 0.5-250μg/L, respectively, with correlation coefficients (R2) all larger than 0.998. Achieved MLODs (S/N=3) varied between 0.1-0.4μg/kg for all bisphenols. The mean recoveries at three spiked levels in edible oil were in the range of 87.3-108%. Intra-day precision (n=6) and inter-day precision (n=5) were <9% and <11%, respectively. This method is of rapid-and-simple pretreatment, accurate and sensitive, and suitable for the simultaneous determination of bisphenols in edible oil.

A selective, sensitive and useful method, based on modified QuEChERS cleanup combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the negative-ion electrospray ionization (ESI-) mode, was developed and validated for the simultaneous determination of three inorganic anions including perchlorate (ClO4-), bromate (BrO3-) and hypophosphite (H2PO2-) in flour. The extraction parameters and LC-MS/MS conditions were optimized by single-factor experiment and sorbent combination in modified QuEChERS clean-up was optimized through response surface analysis. Three target analytes were separated on a normal-phase Phenomenex Luna Silica (2) column (150mm×2.0mm, 5μm, 100Å) with the mobile phase of a mixture of 5mmol/L ammonium acetate water solution and acetonitrile, detected by MS/MS under multiple reaction monitoring and quantified by external standard method. The developed method was validated in terms of the sensitivity, linearity, accuracy and precision, and matrix effect. The method showed a good linearity (R2>0.999) for all analytes in their respective concentration ranges. The ILOQs and MLOQs for perchlorate, bromate and hypophosphite were 0.1, 0.5, 5.0μg/L and 2.0, 6.0, 60.0μg/L, respectively. The average recoveries of three target analytes from the negative samples spiked at three different concentrations were in a range from 84.6% to 104.9%. The intra-day precision (n=6) and inter-day precision (n=5) of the target analytes were in the ranges of 2.9%-6.9% and 6.4%-8.2%. The matrix effect of this method was observed between 0.83 and 1.17 and was acceptable. The validated method was successfully applied to determine the concentrations of these inorganic anions in flour. Results found that perchlorate and hypophosphite were detected in 33 out of 50 and 7 out of 50 flour samples.

A sensitive UPLC-MS/MS method was established for the simultaneous determination of seven fluorescent whitening agents in flour matrix. Samples were ultrasonically extracted by trichloromethane-acetone. Then analytes were separated on a C18 column and detected by MS/MS. The developed method was validated in terms of the linearity, matrix effect, accuracy and precision. The method showed a good linearity (r>0.997) for all analytes in their respective concentration ranges. The LOQ for seven analytes were in the range of 2.5-25.0μg/kg. The matrix effect was not significant and almost negligible. The average recoveries of seven analytes from the negative samples spiked at three different concentrations were in a range from 81.5% to 105%. The intra-day precision and inter-day precision were in the ranges of 2.9-9.0% and 6.7-11.2%. The developed method was successfully applied to analyze forty commercial flours and FWA184 was detected in three samples with the concentrations of 31-60µg/kg.