最新刊期
卷 40 ， 期 12 ， 2021
- 摘要：A new method for the rapid detection of leachables in Huoxiang Zhengqi liquid was developed by ultra-performance liquid chromatography－tandem mass spectrometry（UPLC－MS/MS） with fabric phase sorptive extraction（FPSE）．The fabric extraction phase was prepared by coating polydimethylsiloxane（PDMS） on the cotton fiber cloth through a sol－gel reaction．Effects of extraction time，ionic strength，type of desorption solution，volume of desorption solution and desorption time on extraction efficiency were optimized．A 2.0 cm × 2.0 cm fabric extraction phase and magnetic agitator were placed in a 5 mL sample，extracted for 30 min at 700 r/min，then ultrasonically eluted with 1 mL acetonitrile as the back-extraction solvent for 10 min to obtain the best extraction effect．The results showed that the calibration curves for the analytes showed good linearity with their correlation coefficients（r） not less than 0.996 1．The limits of detection（LOD） and limits of quantitation（LOQ） were in the ranges of 0.5－1.5 μg/L and 1.5－4.0 μg/L，respectively．Spiked recoveries for 8 analytes were in the range of 73.8%－98.2%，with relative standard deviations（RSD，n = 3） of 0.98%－8.4%．In order to simulate the solvent formula of Huoxiang Zhengqi liquid，ethanol/water（1∶1） was selected to extract the plastic packaging bottles．Moreover，in order to get a more reliable and comprehensive extractables profile，isopropanol was also used as the storage solution to obtain an extremely harsh environment．The sample was detected by ultra-performance liquid chromatography－quadrupole time-of-flight mass spectrometry（UPLC－QTOF MS），and the extractables of the sample were screened through the UNIFI software based on a polymer additive library and online screening．There were 33 compounds identified．Then these extractables were targetedly detected in the Huoxiang Zhengqi liquid by UPLC－MS/MS．A total of 4 leachables were detected and quantified．The results of toxicological evaluation based on Toxtree and T.E.S.T software showed that the actual daily intake of the 4 leachables will not exceed the permitted daily exposure，indicating that the content of leachables in Huoxiang Zhengqi liquid is relatively safe．关键词：pharmaceutical packaging materials;extractables and leachables;fabric phase sorptive extraction（FPSE）;fast screening;risk assessment;ultra-performance liquid chromatography－tandem mass spectrometry
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发布时间：2023-02-13 - 摘要：Metabolism of cancer cells is quite different from that of normal cells，which results in great differences appearing in the fluorescence spectra of human plasma．By using this difference，the possibility for using fluorescence spectrum as a tool for the detection of colorectal cancer could be explored．In order to improve the detection accuracy，the competitive adaptive reweighted sampling（CARS） method was used to screen important human plasma fluorescence spectrum variables in this paper，then a partial least squares－linear discrimination analysis（PLS－LDA） was applied to establish a classification model for colorectal cancer patients and non-cancer patients，which was compared with the full-wavelength model and parallel factor analysis model（PARAFAC）．From the evaluation indexes of these three models，the performance of CARS－PLS－LDA model was significantly better than those of the latter two models．The area under curve（AUC） values for the fluorescence spectra of high-wave undiluted group and low-wave diluted group combined with the CARS－PLS－LDA classification model were higher than 0.9．In addition，the sensitivity，specificity and AUC values of the classification model for cancer and adenoma patients in the high wave undiluted group were all 1.000 0．Results showed that the CARS－PLS－LDA model could be used to effectively identify the patients with colorectal cancer．Furthermore，from the data of high wave dilution group and low wave undiluted group，the CARS method preferably obtained the important variables，which could be traced back to the original fluorescence data，determining the corresponding excitation/emission wavelength information，and analyzing the chemical mechanism behind the identification．The results also showed that these excitation/emission wavelength regions were consistent with porphyrin，tryptophan，tyrosine and NADH，indicating that the colorectal cancer samples could be effectively distinguished from the other control samples in these material dimensions．Based on the parallel factor analysis model，it was considered that porphyrin has nothing to do with cancer．The influence variables obtained from the high wave undiluted group data of CARS model mainly concentrated in the excitation wavelength range of 400－420 nm and the emission wavelength range of 610－625 nm，which just accorded with the wavelength range of porphyrin fluorescence．This result suggested that there was a significant difference between the plasma porphyrin concentrations of cancer patients and healthy people．Compared with the former，the results are consistent with relevant experimental studies．The influence variables obtained from the low wave dilution group data of CARS model concentrated in the excitation wavelength of 250－260 nm and the emission wavelength of 310－360 nm，which corresponded to free tryptophan，bound tryptophan and tyrosine in blood．Meanwhile，there were also another excitation wavelength of 260－272 nm and another emission wavelength of 450－500 nm，which was consistent with the fluorescence characteristics of NADH．The results of this study showed that CARS variable screening could significantly improve the performance of colorectal cancer classification model and contribute to the development and research of follow-up cancer clinical diagnosis tools.关键词：fluorescence spectrum;colorectal cancer;competitive adaptive reweighted sampling （CARS）;partial least squares －linear discrimination analysis （PLS－LDA）
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发布时间：2023-02-13 - 摘要：In this paper，gas chromatography－quadrupole time-of-flight mass spectrometry（GC－Q/TOF MS） was used to identify the chemical constituents in the volatile oil of Saposhnikovia divaricate．Firstly，the samples were analyzed under standard EI ionization source mode，and the qualitative software was used for data deconvolution and NIST library comparison．82 compounds were identified，including hydrocarbons，aldehydes，ketones，alcohols，organic acids and esters．Furthermore，the low energy ionization source（lower energy）mode of GC－Q/TOF MS was utilized to determine the molecular ion peaks of the unknown compounds．And then，the secondary mass spectra of unknown compounds were acquired to obtain the fragment ion information so as to infer the molecular formula，and further identify the chemical structures combined with Chemspider database．As a result，two compounds outside the NIST library were identified by this new method as（5E，7E，11S）-5，11-dimethyl-5，7-tridecadien-1-alkyn-4-ol and（6S，7E，9E）-7，9-heptadecadiene-11，13-diyn-6-ol，and three components in the NIST library were identified as 2，4-decadienal，tetradecanoic acid and methyl ester hexadecanoic acid，which were consistent with the automatic matching results and verified the feasibility of the proposed method. To sum up，a total of 84 chemical components were identified from the volatile oil of Saposhnikovia divaricate. This research not only enrich the application of GC－Q/TOF MS in identification on volatile oil of Saposhnikovia divaricate，but also provide a new idea for the rapid and comprehensive identification of other chemicals. In particular，the combination of lower energy and MS2 mode of GC－Q/TOF MS could be applied to the accurate and rapid identification of compounds not included in the NIST library.关键词：Saposhnikovia divaricate;component identification;gas chromatography－quadrupole time-of-flight mass spectrometry（GC－Q/TOF MS）;variable energy ionization source;MS2
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发布时间：2023-02-13 - 摘要：An ultra performance liquid chromatography（UPLC） with solid phase extraction was developed for the simultaneous determination of chlorfenapyr and its metabolite tralopyril in fruits and vegetables．The validation results showed that there was a good linear relationship in the range of 25－5 000 ng·mL-1 with correlation coefficients（r2） of 0.997－1.000. The average recoveries at three spiked levels of 0.05，1 and 2 mg·kg－1 ranged from 84.6% to 111%，with relative standard deviations（RSD，n = 5） of 1.6%－14%．The limits of quantitation（LOQ） were both 0.05 mg·kg－1 for the two target compounds. Field trials were carried out in 12 areas nationwide in 2020，after 360 g·L-1 chlorfenapyr suspension was sprayed once at 20 mL/mu（125.28 g a.i./ha），the dissipation of chlorfenapyr in cabbage accorded with the first-order kinetics equation，and the half-life period was 4.1－11.0 d．When the sampling intervals were 14 d and 21 d，the residual levels of chlorfenapyr in cabbage were lower than 0.05－0.488 mg·kg－1 and lower than 0.05－0.370 mg·kg－1，respectively，while those of tralopyril in cabbage were both lower than 0.05 mg·kg－1．Based on the MRLs of China，14 d was selected as the post harvest interval. The dietary risk assessment revealed that the national estimated daily intake of chlorfenapyr（definition for dietary risk assessment） was 1.28 mg，accounting for 67.7% of the acceptable daily intake，which showed there was no significant dietary risk to residents' health.关键词：ultra performance liquid chromatography;chlorfenapyr;tralopyril;residual evaluation;fruits;vegetables
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发布时间：2023-02-13 - 摘要：Separation of two carnitine enantiomers，i.e. D-carnitine and L-carnitine by ultra-performance convergence chromatography（UPC2） was attempted，and a residue analytical method for these carnitine enantiomers in health food samples was established．The solid and liquid health food samples were ultrasonically extracted with ethyl alcohol as the solvent．After derivatization of the extracting solution，a chiral chromatographic column，Acquity Trefoil CEL1（3.0 mm × 150 mm，2.5 µm） column was adopted for separation．The detection wavelenths for photo-diode array detector（PAD） was 244 nm．The separation effect of the two carnitine enantiomers reached the best when supercritical carbon dioxide and ammonium hydroxide－methanol（1∶99，by volume） were taken as the mobile phases at a flow rate of 1.0 mL/min by gradient elution．Results showed that there were good linear relationships for the two carnitine enantiomers in the range of 0.50－20.00 mg/L，with correlation coefficients（r2） greater than 0.999．The quantitative limits of the method（S/N = 10） for D-carnitine and L-carnitine were both 25 mg/kg．Recovery experiment was carried out within the range of 25－250 mg/kg，and the recoveries at three spiked levels ranged from 86.0% to 110%，with the relative standard deviations（RSD） of 4.3%－7.0%．The method was used to detect standard carnitine racemates purchased from the reagent company in order to investigate its effectiveness and practicability．The results suggested that D-carnitine accounted for 51.2% and L-carnitine accounted for 48.8% in the standard carnitine racemates．This method was also used to detect the contents of D-carnitine and L-carnitine in 10 health foods purchased from the market．The experimental results indicated that D-carnitine wasn't detected in the 10 health food samples，but L-carnitine was detected in all of them，with the content reaching 96%－102% of the label value．With the characteristics of rapid analysis，good separation effect，good reproducibility and low consumption of organic solvent，this method is applicable for both the determination of L-carnitine content in health food samples and purity analysis．It provides a scientific support for the development and use of chiral drugs as well as the formulation of relevant regulations.关键词：ultra-performance convergence chromatography;carnitine;health foods;enantiomer;chiral separation
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发布时间：2023-02-13 - 摘要：Screening of potential risk factors in food is very important for the ensurement of food safety．Pesticide residue is one of the important factors affecting the quality and safety of agricultural products，and the multi-residue detection of pesticides in complex matrices is still a challenging task．A rapid non-targeted screening strategy for pesticide residues in fruits and vegetables was proposed in this study，based on ultra-performance liquid chromatography－high resolution mass spectrometry（UHPLC－HRMS）．Meanwhile，an analytical method for pesticide residues in complex substrates was established，including rapid sample pretreatment，accurate separation by UHPLC and detection by HRMS．Brief steps for the method construction are described as follows．Firstly，the pre-treatment method including purification agents and extraction solvents were optimized，and the acetonitrile containing 1% acetate and dispersive solid phase extraction with 20 mg PSA + 20 mg C18 + 2.5 mg GCB + 150 mg MgSO4 were selected for sample preparation，owing to its relatively high recoveries for most of pesticides．Secondly，the instrument conditions were optimized，the separation was performed on an Accucore aQ C18 column，and the high-throughput qualitative screening and quantitative detection were performed by Full Scan/ dd－MS2．More importantly，the retention time correction strategy was introduced to calibrate the retention time generated under different LC－MS conditions．Finally，a high-resolution database containing 651 pesticides was established based on the original commercial database and the actual situation of the limits of different pesticides on agricultural products in various countries．Under the optimized conditions，108 kind of pesticides in fruit and vegetable matrix were analyzed．Results showed that there were good linear relationships for all the pesticides in the concentration range of 5－500 μg/L，with their correlation coefficients（r2） larger than 0.99．The limits of detection（LODs，S/N ≥ 3） for all the pesticides were in the range of 0.002－1.5 μg/kg，while the limits of quantitation（LOQs） were 5 μg/kg．At three spiked levels of 5，25，100 μg/kg，the recoveries for 106 pesticides except cyromazine and chlormequat chloride ranged from 61.2% to 120%，with relative standard deviations（RSD） of 0.1%－9.9%．The established method was successfully applied to the analysis of fifty－eight cowpea and twelve citrus samples for pesticides screening．Results showed that this method was rapid，accurate and sensitive，and was suitable for the rapid screening and quantitative analysis of unknown pesticide residues in agricultural products.关键词：ultra-performance liquid chromatography－high resolution mass spectrometry （UHPLC－HRMS）;pesticide residue;untargeted;fruits and vegetables
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发布时间：2023-02-13 - 摘要：In this paper，a new type of colloidal gold lateral flow test strip（AuNPs@polyA－DNA） was fabricated based on aptamer recognition of kanamycin molecule and non-thiolated DNA modified colloidal gold nanoprobe. Effects of the strip components on color development were investigated，including concentration of aptamer，proportion of streptavidin（SA） to Biotin－DNAT，concentration of SA－Biotin－DNAT，conjugate reaction time and temperature．The optimized experimental conditions were as follows：Running buffer：4xSSC（0.5% Tween 20），molar ratio of SA to Biotin－DNAT：1∶6，concentartion of SA－Biotin－DNAT conjugate sprayed at T line：4 μmol/L，concentartion of aptamer：10 nmol/L，incubation of aptamer： ambient temperature for 20 min．The results demonstrated that 25 ng/mL kanamycin could be discriminated with the naked eyes．The quantitative determination of kanamycin in the range of 5.0－125 ng/mL could be carried out by a colloidal gold reader，with a detection limit of 1.5 ng/mL．The test strip was applied to the determination of kanamycin in honey，with recoveries of 95.1%－105% and relative standards deviation（RSD） of 3.4%－8.5%．The strip could be used for the detection of kanamycin in real samples with the advantages of high sensitivity，high specificity，simple structure and high repeatability．关键词：gold nanoparticles;lateral flow test strip;kanamycin;aptamer
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发布时间：2023-02-13 - 摘要：Mercury is one of the toxic and harmful heavy metal pollutants in the environment．It can enter the human body through the accumulation of food chain，thus damaging the human health．Recently，the control of mercury pollution has attracted much attention．The main detection methods for mercury in water involve inductively coupled plasma optical emission spectrometry（ICP－OES），atomic absorption spectrometry（AAS），atomic fluorescence spectrometry（AFS） and inductively coupled plasma mass spectrometry（ICP－MS）．However，these methods generally could not meet the requirements for convenient，rapid and sensitive on-site detection．Fluorescence detection method has the advantages of simple operation，rapid response，high sensitivity，good selectivity，and independent of large-scale instruments，which could fully meet the requirements for rapid detection of mercury in water．Based on the fluorescence quenching mechanism of Hg2+ on carbon quantum dots（CQDs），a rapid method based on nitrogen and sulfur doped fluorescent CQDs was established for the detection of Hg2+ in water．The fluorescent CQDs were synthesized by one-step hydrothermal method with sodium citrate，waste water and tetramethylthiuram disulfide as carbon，nitrogen and sulfur sources．Effects of the spectral properties as well as pH value，reaction time and component content on fluorescence intensity were all investigated．In the process of Hg2+ detection，the relationships of fluorescence quenching with reaction time and pH value were further investigated，and the kinetic mechanism of quenching reaction was analyzed．The experimental results showed that the fluorescence quenching reaction of Hg2+ on CQDs was rapid， which has a high quenching effect at pH 7.0，while the fluorescent CQDs had good selectivity and anti-interference ability for Hg2+．Under the optimized conditions，the detection limit for Hg2+ was 0.95 μg/L，and the linear range was 1－6 μg/L.The accuracy of this method was investigated with surface water，and the recoveries for actual water samples ranged from 100% to 126%，with relative standard deviations（RSD） of 0.31%－3.9%.This method was suitable for rapid and convenient on-site detection of Hg2+ in waste water samples.关键词：waste water;carbon quantum dots （CQDs）;mercury;rapid detection
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发布时间：2023-02-13 - 摘要：In this study，a molecularly imprinted polymer was prepared by Pickering double emulsion method using mesotrione as template molecule，methyl methacrylate as functional monomer，divinylbenzene as coupling agent and lignin as a stable particle．The polymer was characterized by Fourier transform infrared spectroscopy，scanning electronic microscopy，X-ray diffraction and contact angle．Moreover，the static adsorption，dynamic adsorption and selective adsorption of this polymer toward mesotrione were discussed．Results of Scatchard analysis showed that there existed two kinds of binding sites for mesotrione，the values of apparent maximum absorption capacity（Qmax） and equilibrium dissociation constant（Kd） were calculated as follows：Qmax1 = 32.31 mg/g，Kd1 = 116.28 mg/L，Qmax2 = 89.99 mg/g and Kd2 = 413.22 mg/L．The adsorptive dynamics results showed that the adsorption of the polymer toward mesotrione accorded with quasi-secondary dynamics model．The prepared molecularly imprinted polymer was used as the dispersant of matrix solid-phase dispersion for separation of nitrosulfuron in maize．The optimal extraction conditions were as below：the mass ratio of molecularly imprinted polymer to sample was 3∶2，the grinding time was 10 min，washing solvent was 2 mL 20% methanol solution，and 5 mL 5% acetic acid－acetonitrile was used as elution solvent. Under the optimum conditions，the limit of detection for mesotrione was 0.018 μg/g．The recoveries ranged from 97.0% to 98.4%，with relative standard deviations（RSDs） of 0.70%－5.6%．This method could reduce the analysis time and the use of organic solvents，and improve the selectivity and analysis efficiency．关键词：Pickering double emulsion;mesotrione;lignin;molecularly imprinted polymers;matrix solid-phase dispersion
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发布时间：2023-02-13 - 摘要：Cobalt oxyhydroxide（CoOOH）nanoflakes，an emerging and promising functional two⁃dimensional（2D）nanomaterial with remarkable physical and chemical properties，have received much attention in recent years.Until now，all kinds of fluorescent nanoprobes by integrating CoOOH nanoflakes with fluorescent inorganic nanomaterials have been reported.However，the synthesis procedures for fluorescent inorganic nanomaterials employed in these nanoprobes are generally time⁃consuming and complex，and most of them are limited to sensing ascorbic acid. Therefore，investigation on the interaction between CoOOH nanoflakes and biomolecule，and the development of new CoOOH⁃based fluorescent nanoprobe to broaden biological applications is very interesting and also of great importance.Herein，a turn⁃on fluorescent nanoprobe based on CoOOH nanoflakes and BSA⁃templated gold nanoclusters（BSA@AuNCs）was constructed for sensitive and label⁃free detection of biothiols.It was found that negative BSA@AuNCs were easily and effectively assemblied on the surface of positive CoOOH nanoflakes to construct a BSA@AuNCs－CoOOH nanoprobe in a short time through the electrostatic interaction between scaffold protein BSA and CoOOH nanoflakes.As a result，the red strong fluorescence emitted by BSA@AuNCs could be efficiently quenched by CoOOH nanoflakes through inner⁃filter effect（IFE）.The CoOOH nanoflakes in the BSA@AuNCs－CoOOH nanoprobe were degraded in the presence of the target biothiol due to the specific redox reaction between biothiols and CoOOH nanoflakes，leading to the release and fluorescence recovery of BSA@AuNCs.On the basis of the emission increase of BSA@AuNCs，a robust fluorescence sensing strategy for sensitive and selective detection of biothiols was developed，which was demonstrated to be suitable for the quantitative analysis of biothiols（Cys，GSH and Hcy）in the range of 0.05－150 μmol/L，with a detection limit as low as 30 nmol/L.Furthermore，this nanoprobe exhibited a high selectivity towards biothiols other than amino acids，metal ions and saccharides.The practical application of this nanoprobe was verified，and it was successfully applied to the detection of biothiol（Cys）in human serum samples.The developed biosensing strategy might provide a simple，facile，cost⁃efficient and rapid platform for biothiols⁃related clinical disease diagnosis.关键词：fluorescent nanoprobe;CoOOH nanoflakes;protein－CoOOH interaction;protein⁃templated gold nanoclusters;label⁃free;biothiols
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发布时间：2023-02-13 - 摘要：An ultrahigh performance convergence chromatography（UPC2） was established for the separation of two kinds of clenbuterol stereoisomers，which was applied to the residue analysis of swine urine samples．The experimental conditions，including back pressures，types of constant volume reagents，gradient elution conditions and types of purification columns were optimized．The best experimental conditions were as follows：the back pressure：13.8 MPa，constant volume reagent：heptane，gradient elution condition：gradient 3，purification column：PCX column．The swine urine samples were extracted with ethyl acetate，then purified on a cation exchange solid phase extraction column．The separation of two clenbuterol stereoisomers was performed on a CHIRALPAK IA－3（4.6 mm × 100 mm，3 µm） chiral column by gradient elution，with supercritical carbon dioxide and 10 mol/L ammonium acetate－methanol（0.5∶99.5，by volume） as mobile phases at a flow rate of 2.0 mL/min．The detection wavelenth for photo-diode array detector（PDAD） was set at 241 nm．Results showed that the linear ranges for two clenbuterol stereoisomers were between 50 µg/L and 10 000 µg/L，with corelation coefficients greater than 0.999 8．The limits of quantitation（S/N = 10） for （+）－clenbuterol and （－）－clenbuterol were both 1.0 µg/L．The recoveries at three spiked levels of 1.0，5.0，20.0 µg/L ranged from 76.4% to 94.5%，with relative standard deviations（RSD） of 3.6%－6.6%．The method was used to detect standard clenbuterol racemates and 20 swine urine samples．Results showed that clenbuterol racemates contained two kinds of clenbuterol stereoisomers，i.e.（+）－clenbuterol and（－）－clenbuterol．The contents of （+）－clenbuterol and （－）－clenbuterol were 5.6 mg/L and 5.5 mg/L，respectively. The content ratio of（+）－clenbuterol and （－）－clenbuterol in standard clenbuterol raceme complied with the ratio reported in literature．Two kinds of clenbuterol stereoisomers were undetected in 20 swine urine samples．With the characteristics of rapid analysis，good separation effect，good reproducibility and less consumption of organic solvent，this method is applicable for the determination of clenbuterol stereoisomer content in swine urine samples．It provides a scientific support for the development and use of chiral drugs as well as the formulation of relevant regulations.关键词：ultrahigh performance convergence chromatography（UPC2）;clenbuterol;swine urine;stereoisomer;chiral separation
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发布时间：2023-02-13
Scientific Papers
- 摘要：A QuEChERS/high performance liquid chromatography－tandem mass spectrometry（QuEChERS/HPLC－MS/MS） was established for the simultaneous detection of seven phenolic environmental hormones in citrus．Effects of different extraction solvents，extraction time，extraction solvent volume and adsorbent types on the extraction efficiency for target compounds were compared．The samples were ultrasonically extracted twice with acetonitrile containing 0.1% formic acid after homogenization，and then purified by modified QuEChERS method with 50 mg PSA + 50 mg C18．The target compounds were separated on a Waters ACQUITY UPLC BEH C18 column（50 mm × 2.1 mm，1.7 μm） by gradient elution，with water containing 0.5 mmol/L ammonium acetate and methanol as the mobile phases at a flow rate of 0.2 mL/min and a column temperature of 40 ℃．The mass spectra were recorded by negative electrospray ionization under the multiple reaction monitoring（MRM） mode．External standard method was used for the quantitative analysis．Under the optimized conditions，bisphenol A（BPA），nonylphenol（NP），bisphenol F（BPF） showed good linear relationships within the range of 0.5－100 μg/L，while bisphenol B（BPB），bisphenol S（BPS），n-nonylphenol（4-n-NP），n-octylphenol（4-n-OP） exhibited good linear relationships within 0.2－100 μg/L．The correlation coefficients（r2） were not less than 0.994 1. The detection limits（LOD）and the quantitation limits（LOQ）of the method were in the ranges of 0.2－0.5 μg/L and 0.5－1.5 μg/L，respectively．At the three spiked levels of 10，250 and 500 μg/kg，the average recoveries for the target compounds ranged from 88.5% to 109%，with the relative standard deviations（RSD）of 1.2%－9.0%．The method was applied to the detection of 8 commercially available citrus samples．BPA was detected in 7 kinds of citrus，4-n-OP was detected in 5 kinds of citrus，NP and 4-n-NP were detected in 3 types of citrus，BPB was detected in 1 type of citrus，and BPF and BPS were not detected in all samples．The above results indicate that bisphenol environmental hormones are commonly found in commercially available fruits and need to be paid attention to．This method was simple to operate，rapid，sensitive，accurate and highly precise．It was suitable for the determination of 7 bisphenol environmental hormones in citrus．关键词：high performance liquid chromatography－tandem mass spectrometry;QuEChERS;environmental hormones;citrus
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发布时间：2023-02-13 - 摘要：Atrazine（ATR） is one of the most widely utilized triazine herbicides. The environmental pollution and potential risk to aquatic products safety caused by ATR and its residues are becoming more and more prominent．In this study，a gas chromatography－tandem mass spectrometry（GC－MS/MS） with solid phase extraction（SPE） was developed for the quantitative determination of ATR and its main metabolites，including deethylatrazine（DEA），didealkylatrazine（DDA） and deisopropylatrazine（DIA） in aquatic products．The parameters affecting the extraction and purification efficiency，such as type of extraction solvent，mode of purification method were optimized．The analytes in aquatic products were extracted with acetonitrile，then purified on a GCB/NH2 solid phase extraction column，finally analyzed by GC－MS/MS under multiple reaction monitoring（MRM） mode．Results showed that there were good linear relationships for ATR，DEA，DDA and DIA in the concentration range of 0.5－100.0 μg/L with their correlation coefficients（r2） of 0.999 1－0.999 9．The limits of detection（LOD） were between 0.02 μg/kg and 0.13 μg/kg. Meanwhile，the average recoveries for the samples at three spiked levels of 10.0，20.0 and 50.0 μg/kg ranged from 83.6% to 98.4%，with relative standard deviations（RSD，n = 3） of 3.6%－8.1%．Furthermore，the contaminant occurrence of ATR and its metabolites in aquatic organisms from the Xiangshan Harbor were analyzed，and ATR，DEA and DIA were all detected in the collected samples. Given the high detection rate of ATR and its metabolites，further investigation on aquatic products safety risks are needed．With excellent accuracy，sensitivity and precision，the method provided a good technique support for the monitoring and risk evaluation of ATR and its metabolites in aquatic products.关键词：gas chromatography－tandem mass spectrometry;atrazine;metabolites;solid phase extraction;aquatic products
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发布时间：2023-02-13 - 摘要：Aflatoxin（AFT） is a type of difuran ring toxins produced by some strains such as aspergillus flavus and aspergillus parasiticus．There are about 20 kinds of its derivatives，of which aflatoxin B1（AFB1）is the most widely distributed，most toxic，and most harmful．Therefore，extremely strict regulations have been imposed on the levels of AFB1 in various foods worldwide．At present，the existing detection methods for AFB1 require large-scale instruments or have poor reproducibility，and most of them are difficult to achieve rapid on-site detection to meet market needs．Fluorescence analysis is a common quantitative analysis method，which is simple，fast，and sensitive．A small portable fluorscence instrument can easily be fabricated by assembling small optical devices，such as light source and small optical detector，which has the potential for rapid on-site testing. In this work，a fluorescence spectral detection device was constructed with a LED lamp as the excitation light source and a small fiber-optic spectrometer as the detection equipment．Based on the fluorescence enhancement effect of Hg2+ on AFB1，a rapid fluorescence spectrometric method was established for the quantitative analysis of AFB1，using a Lumina fluorescence spectrophotometer at an excitation wavelength of 370 nm and an fluorescence detection wavelength of 443.2 nm. The pH value，solvent ratio，reaction time and other conditions of the reaction between Hg2+ and AFB1 were optimized．Meanwhile，the interference factors of this method were explored and the anti-interference ability of the method was evaluated. Under the optimized conditions，there is a linear relationship between the fluorescence emission intensity of the AFB1－Hg2+ system and AFB1 concentration in the range of 3－90 μg/L，with a correlation coefficient（r2） of 0.996 and a detection limit of 0.913 μg/L．The first step of this method is to extract the AFB1 in the sample by magnetic stirring method，then making the extract clarified by filtering it with glass fiber filter paper，and finally using the special AFB1 immunoaffinity column to refer to the instructions for the aspergillus flavus in the sample to be tested．AFB1 was specifically enriched and eluted with methanol，and then Hg2+ was added to the eluate to test the fluorescence spectrum of the sample．This method was used to detect AFB1 in two kinds of cornflours．The spiked recoveries ranged from 84.1% to 107%，with RSDs of 1.1%－7.1%．This study provides a new rapid method with high sensitivity and precision for the rapid detection of AFB1. In the future，it is expected that the detection method equipment will be assembled into a rapid detection kit，and the method is expected to be applied to the field of rapid detection.关键词：aflatoxin B1(AFB1);LED excitation fluorescence spectrometry;Hg2+;rapid detection
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发布时间：2023-02-13 - 摘要：An ultrahigh performance liquid chromatography coupled with quadrupole－orbitrap mass spectrometry（UHPLC－Quadrupole－Orbitrap MS） was developed for the determination of cyromazine and its metabolite melamine in pig urine samples．The pig urine sample（2.0 g） was ultrasonically extracted with 1% trichloroacetic acid under the pH value of the extraction mixture lower than 3，followed by purification with a mixed cation solid phase extraction column（MCX），then the eluent from the MCX column was blow dried under nitrogen flow，and finally reconstituted with 95% acetonitrile aqueous solution．The reconstituted solution 10 times diluted was injected into the UHPLC－Quadrupole－Orbitrap system using a Syncronis HILIC column（100 mm × 2.1 mm，1.7 μm） at 35 ℃，with 10 mmol/L ammonium acetate and acetonitrile as the mobile phases．The mass spectrometer was operated in positive electrospray（ESI + ） and parallel reaction monitoring（PRM） mode．Qualitative analysis was carried out according to the accurate masses of each target compound，its fragment ions，and the abundance ratios of the fragment ions．The external standard method and internal standard method were used for the quantification of cyromazine and melamine，respectively．Method validation showed that there were good linear relationships for the two targets in the range of 0.2－50.0 ng/mL，with their correlation coefficients（r2） larger than 0.99．At three spiked levels of 1.0，2.0 and 150.0 μg/kg，the recoveries for cyromazine and melamine in pig urine sample ranged from 78.0% to 105%，with relative standard deviations（RSD） no more than 11%．The same spiked samples were used for comparison between PRM of orbitrap and multiple reaction monitoring（MRM） mode of triple quadrupole．The results obtained exhibited no significant difference，indicating that both methods have good quantitative ability for determination of cyromazine and melamine in pig urine sample．With good recovery，dynamic range and quantification accuracy，the developed method could be applied to the simultaneous qualitative and quantitative analyses of cyromazine and melamine residues in pig urine samples．关键词：pig urine;cyromazine;melamine;ultrahigh performance liquid chromatography coupled with quadrupole－orbitrap mass spectrometry
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发布时间：2023-02-13 - 摘要：Molecular imprinted polymers（MIPs） play a important role in the separation and enrichment of trace substances due to their specific recognition capability．In this paper，a method for preparing porous magnetic MIPs（mMIPs） microspheres was developed via the oil-in-water soap-free liquid emulsification technique to cope with a widely used pesticide α-naphthylacetic（NAA）．The preparation was done by simply mixing methacrylic acid－styrene polymer precursor，NAA，Fe3O4 magnetic fluid and 2，2-azobisisobutyronitrile together in one pot．The product was characterized by scanning electron microscopy，transmission electron microscopy and Fourier transform infrared spectroscopy，respectively．The results showed that it is a kind of microspheres with a size distribution about 80 μm．And there are lots of pores distributed in/on the particle with diameters ranging from 1 to 10 μm．Such a porous structure could effectively increase the specific surface area，the number of contact recognition sites and the column capacity of the MIPs，as well as the mass transfer rate．Adsorption kinetics experiments showed that the adsorption equilibrium could be reached in 120 minutes．Meanwhile，the results of the adsorption isotherms and Scatchard analysis revealed that there exist two type of affinity binding sites for NAA in the MIPs．The dissociation constant and apparent maximum binding capacity were found to be －128.20 µg·mL－1 and －19.50 mg·g－1 for the low affinity binding site，and 161.30 µg·mL－1 and 29.35 mg·g－1 for the high affinity binding site．As comparison，there only existed one type affinity binding site for none-imprinted MIPs with the dissociation constant and apparent maximum binding capacity of 61.39 µg·mL－1 and 4.658 mg·g－1，respectively．Moreover，the results of the adsorption kinetics studies confirmed that the adsorption process matched the pseudo-second-order kinetic model well，indicating that it was controlled mainly by chemical adsorption．All results demonstrated the high specificity of mMIPs towards NAA．To investigate the feasibility of the mMIPs，they were used in the determination of NAA in real sample of tomato juice by high performance liquid chromatography with UV－Vis detector．The average recoveries for the sample at three spiked levels ranged from 78.7% to 89.2%，with relative standard deviations（RSDs） less than 3.9%（n = 3）．Notably，the average recoveries still could reach 80.3% even when the amount of NAA in tomato juice is only 0.005 μg·mL－1 which is far lower than the maximum residue limits of NAA stipulated by GB and the European Union（100 and 60 μg·kg－1，respectively）．All experimental results indicated that it was readily to perform the preparation with the proposed method，and the mMIPs exhibited many merits，including the high selectivity and specificity for NAA，the fast mass transfer rate and the easy operation．With the MIPs，the high matrix effects of real samples could be eliminated effectively，and the accuracy and reliability could be improved significantly for NAA determination in practice.关键词：magnetic molecularly imprinted polymers;α-naphthylacetic;soap-free liquid emulsification method;tomato juice
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发布时间：2023-02-13 - 摘要：A 2，4-dinitrophenylhydrazine colorimetric method was developed for the rapid determination of aldehydes and ketones in cooking fumes．The method was based on the formation of a yellow phenylhydrazone compound from the carbonyl groups of aldehydes and ketones，and 2，4-dinitrophenylhydrazine under heating and acid catalyzed conditions，which further produced a red or burgundy-coloured chromogenic substance under strongly alkaline conditions．Separation of the chromogenic substance from 2，4-dinitrophenylhydrazine at the maximum absorption peak of UV-visible spectrum could be used for the detection of aldehydes and ketones．The optimal conditions for the reaction were as follows：reaction temperature：60 ℃，reaction time：30 min，volume of concentrated hydrochloric acid：45 μL，ratio of aldehyde to hydrazine：1∶50，amount of alkali：2.0 mL 60 g/L KOH solution．Under the optimized conditions，the method could be carried out with simple operation，high sample throughput and wide linear range（2.5－15 μmol/L）．It was applied to the analysis of actual catering oil fume samples，with spiked recoveries of 80.0%～84.0% and relation standard deviations（RSD） less than 5%．This method provides a reference for the rapid and efficient determination of high-concentration aldehydes and ketones in cooking fumes.关键词：2，4-dinitrophenylhydrazine;colorimetric method;aldehydes and ketones;cooking fumes
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发布时间：2023-02-13
Experimental Techniques and Methods
- 摘要：Consumer products have close relationship with people′s daily lives．With the rapid development of social economy and the improvement of people′s living standards，the quality of consumer products has drawn increasing concerns from the majority of consumers．In recent years，new materials and technologies have continually emerged．While benefiting consumers，they have also put forward higher requirements for the authenticity and discrimination of consumer products．Accurate and reliable detection techniques are the fundamental measures against counterfeit consumer products．In this paper，the research progress of sensory inspection，microscopic identification，physical and chemical testing，instrumental analysis and multivariate statistical analysis in the authenticity detection and quality traceability of consumer products was reviewed，and the application prospects were discussed，aiming to provide a useful technical reference for the authenticity detection and quality control of consumer products.关键词：consumer products;authenticity detection;review
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发布时间：2023-02-13 - 摘要：Improvised explosives related to terrorism have seriously threatened the homeland security and social stability as their devices could be easily constructed using readily available，low-cost，and legally purchased ingredients，which make them an ideal alternative option to heavily regulated military explosives．As one of the most popular improvised explosives，peroxide-based explosives（PBEs） are frequently used in terrorist incidents according to the reports of world media．As a result，the detection of PBEs is of great urgency for reducing or potentially stemming explosive-related terrorist attacks．Hydrogen peroxide，as precursor and degradation product，is an inevitable part of PBEs，which is a representative object and usually selected as target analyte when detecting PBEs．Thus，lots of methods have been developed for the detection of hydrogen peroxide，including mass spectrometry，chromatography，electrochemical，and chemiluminescence，etc．Among various types of detection methods，colorimetric and fluorescent detection methods hold considerable promise due to their potential for high sensitivity，excellent specificity，portability，and ease of on-site visual detection．This paper reviewed not only the developing trend of visually detecting hydrogen peroxide in the field of improvised explosive detection，but also how the design strategy can be realized with different detection modes by regulating probe structures and exploring new reaction mechanisms．Nowadays，although excellent sensitivity has been achieved by the ingenuity and artistry inherent to fluorescence turn-on mode via designing diverse fluorescent probes，the anti-interference of visual detection for on-site detection still remains a significant challenge．Recently，a new generation of visual detection method with complementary advantages by combining fluorescent reaction with colorimetric reaction，known as dual-mode detection，has emerged with a fundamentally improvement of anti-interference and opened the door to new development．Due to the necessarily limited scope of this review，we are only able to introduce some of the representative contributions that have general or potential applicability in the field of explosive detection．Notably，to avoid repetition with other reviews discussed specifically in the biological field，this review does not discuss the method based on peroxidase for colorimetric or fluorescent detection of hydrogen peroxide．Diverse methodologies have been summarized for colorimetric or fluorescent detection of hydrogen peroxide，but this review would be rather regarded as an opening remark than draw conclusions since future development of scientific research is filled with uncertainty．It is hoped that this review will not only assist researchers in designing their own experiments，but also provide all the necessary insights for visually detecting peroxide explosives．关键词：explosive;hydrogen peroxide;colorimetric;fluorescent method;visual detection
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发布时间：2023-02-13 - 摘要：Telomerase is a ribonucleoprotein which can catalyze the addition of single strand repeat units（TTAGGG）n onto the 3'ends of telomeres in the eukaryotic chromosomes，preserving telomeric length and stability．Compared to human somatic cells，it is testified that telomerase activity is overexpressed in over 85% of all known human cancer cells，indicating that telomerase would be used as a biomarker for the detection of tumor cells．Therefore，a reliable method for telomerase detecting plays a crucial role in the diagnosis and treatment of malignant tumors．Since telomerase was discovered in 1985，telomerase activity detection methods have made great breakthroughs in the following 30 years of continuous reform and development．In this paper，the methods for detecting telomerase activity in the past three years were reviewed，such as chemiluminescence method，electrochemistry method，fluorescence analysis method as well as colorimetry．To cut the long story short，the aim of this paper is to have a more comprehensive understanding of the current research progress of telomerase activity detection，which may be of great help to the design of new telomerase activity detection protocols and provide some brand new ideas for overcoming the challenges of telomerase activity detection methods in clinical trials in the future.关键词：telomerase activity;chemiluminescence;electrochemical method;fluorescence analysis method;colorimetry
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发布时间：2023-02-13
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