最新刊期
卷 41 ， 期 8 ， 2022
- 摘要：Enzyme-catalyzed reactions are characteristic of high selectivity and high efficiency．Specially designed metal－organic frameworks（MOFs） have catalytic activities similar to natural enzymes，and their porous structures also provide a large number of active sites for catalytic reactions．In this paper，a novel nanozyme NC@MIL－100（Fe） was prepared based on the electrostatic interaction between needle coke（NC） and MOF material（MIL－100（Fe）），which was applied to the analytical methods development of biothiols．The inherent enzyme-like activity of NC was made full use for the new material，whose lamellar structure could effectively avoid the agglomeration phenomenon of MIL－100（Fe），improving the overall catalytic effect of the material．Compared with needle coke and MIL－100（Fe），NC@MIL－100（Fe） as nanozyme has a stronger affinity for the substrate and a faster reaction rate，thus showing a better peroxidase-like catalytic activity．Its performance was evaluated with 3，3′，5，5′-tetramethylbenzidine（TMB） and H2O2 as substrates，and the Michaelis constants（Km） obtained were 0.27 mmol/L and 0.43 mmol/L，respectively，which were 1.61 times and 8.6 times smaller than that of horseradish peroxidase．The material was applied to the development of analytical methods for glutathione and cysteine，with the linear ranges of 3－70 μmol/L and 1－80 μmol/L，and the detection limits of 0.33 μmol/L and 0.22 μmol/L，respectively，showing the advantages of wide linear range，low detection limit and good selectivity．Furthermore，this material was successfully applied to the detection of biothiols concentration in human serum with satisfactory results．关键词：nanozyme;needle coke;MIL－100（Fe）;glutathione;cysteine
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发布时间：2023-01-04 - 摘要：The petrochemical industry is one of the pillar industries in China. The pollutants，such as phthalates（PAEs），may be emitted into the atmosphere during the plastic production of the petrochemical industry. PAEs are one of the important plasticizers in the plastic industry，which are considered to be endocrine-disrupting chemicals for humans. However，few studies focus on the pollution of PAEs in the petrochemical industry，and there is limited understanding of the potential risks. In this study，PAEs in atmospheric particulate matter （TSP） at two petrochemical regions of Hainan（HNPB） and Guangdong （GDPB） provinces were analyzed. The results showed that the pollution level of PAEs in HNPB was significantly higher than that in GDPB，but both levels were generally lower than those in most cities in China. High PAEs concentrations in TSP were generally associated with the plastic industry，paper mill and ports. The average emissions of ∑PAEs for the major enterprises at two petrochemical regions were estimated using a simplified dispersion model，and the mass ranged from 0.48 to 191 kg for enterprises. The emissions mainly depended on the enterprise types. Health risks of humans for PAEs exposure were all under acceptable levels at two petrochemical regions. The correlations of PAEs in TSP largely depended on their similar applications and the coexistence in industrial products. Temperature，relative humidity and windspeed were the important meteorological factors influencing the concentrations of TSP-bound PAEs. This study is significant in providing the pollution characteristics，emissions，and influencing factors of TSP-bound PAEs at the petrochemical regions.关键词：petrochemical region;total suspended particulates;phthalates （PAEs）;emission estimation;health risk assessment
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发布时间：2023-01-04 - 摘要：This study proved the feasibility of using supercritical fluid chromatography（SFC） in rapid quantification of evodiamine and rutaecarpine in Evodia rutaecarpa（Juss.） Benth.（E. rutaecarpa）. The two alkaloids were firstly extracted by supercritical fluid extraction（SFE）．As a result，the developed SFE conditions were as follows，sample （120－200 mesh）/cellulose acetate=1∶1，20% ethanol as modifier，40 ℃，25 MPa and the CO2 flow rate of 8 mL/min．The developed SFC method was carried out on a 2－EP column，with methanol as modifier at a flow rate of 1.4 mL/min，a column temperature of 35 ℃ and a back pressure of 15 MPa．The baseline separation of evodiamine and rutaecarpine was completed within 6 min．After verification，the SFC method was confirmed to be linear with correlation coefficients（r2） of 0.999 8，good precision（RSD below 0.50%） and accuracy（recoveries of 102%－109%）．Meanwhile，limits of detection（LODs）and limits of quantitation（LOQs） for evodiamine were 1.00 and 3.33 μg/mL，while LOD and LOQ for rutaecarpine were 0.95 and 3.17 μg/mL，respectively．Finally，the method was applied to the determination of contents of evodiamine and rutaecarpine in ten E．rutaecarpa samples from 4 areas．The total content of target alkaloids accounted 2.95% for Guangdong，1，0.51% for Guangdong，2，1.27% for Guizhou，3，1.00% for Hunan，4，0.93% for Hunan，5，1.81% for Jiangxi，6，0.73% for Jiangxi，7，0.58% for Jiangxi，8，0.41% for Jiangxi，9 and 0.36% for Jiangxi，10．Although the ten samples all meet the requirements for the Chinese Pharmacopoeia，the origin difference of sample quality is very obvious，and the samples from the same place also have differences．In addition，the developed method was compared with the Pharmacopoeia method（2020 Edition）．The results of content determination by the two methods were similar （1.27% by SFC vs．1.12% by Pharmacopoeia），while the time required by SFC（6 min） was significantly shorter than that by the Pharmacopoeia method（25 min）．This work showed the potential of SFC in the fast quantification of active components in traditional Chinese medicines．关键词：supercritical fluid chromatography（SFC）;supercritical fluid extraction（SFE）;quantification;Evodia rutaecarpa（Juss.） Benth.;evodiamine;rutaecarpine
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发布时间：2023-01-04 - 摘要：The anion of acidic ionic liquid 1-butyl-3-methylimidazole hydrogen sulfate（［C4MIM］［HSO4］） reacted with carbonate to produce carbon dioxide．The extraction process was promoted by carbon dioxide bubbles．Meanwhile，the cation of ［C4MIM］［HSO4］ reacted in situ with ammonium hexafluorophosphate（NH4PF6） to form hydrophobic ionic liquid 1-butyl-3-methylimidazole hexafluorophosphate ［C4MIM］［PF6］．［C4MIM］［PF6］ was separated from water due to their immiscibility with the water．The extraction phase was collected by centrifugation．An in-situ effervescent assisted microextraction method based on acidic ionic liquid was established for the analysis of brilliant blue FCF and erythrosine B in beverage and candy samples．Effects of the amount of acidic ionic liquid，sodium bicarbonate and salt on the extraction efficiency of the two pigments were investigated．The optimum conditions were as follows：the amount of acidic ionic liquid was 400 mg，the amount of sodium bicarbonate was 0.4 g and the amount of salt was 1.5 g．Under the optimal conditions，there were good linear relationships for brilliant blue FCF and erythrosine B in the range of 0.005－5 µg/mL，with their correlation coefficients not less than 0.993 3．The limits of detection（LODs） and limits of quantitation（LOQs） were in the range of 0.002－0.005 µg/mL and 0.007－0.017 µg/mL，respectively．Additionally，the recoveries for two synthetic pigments at two spiked levels of 0.05 and 0.5 µg/mL ranged from 92.2% to 107%，with the intra-day and inter-day relative standard deviations（RSDs） both 2.2%－8.7%．The proposed method was successfully applied to the detection of two target pigments in beverage and candy samples．The results showed that the method was environmentally friendly，simple and accurate．It could be used for the determination of brilliant blue FCF and erythrosine B in beverage and candy samples．关键词：ionic liquid;effervescence assisted microextraction;synthetic pigments;beverage;candy
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发布时间：2023-01-04 - 摘要：An ultra-fast liquid chromatography－triple quadrupole－linear ion trap mass spectrometry （UFLC－QTRAP－MS/MS） method was developed for the simultaneous determination of 33 active constituents consisting of flavonoids，organic acids，nucleosides，and amino acids in Taxilli Herba．The stems branches and leaves of Taxilli Herba from different hosts were also compared and analyzed．The optimum conditions for the preparation of the test solution were selected by the Box－Behnken response surface method（BBD－RSM）．The target constituents were separated on an XBridge® C18（4.6 mm × 100 mm，3.5 μm） analytical column by gradient elution using 0.1% formic acid aqueous solution and methanol as mobile phases，then analyzed by mass spectrometry with an electrospray ion source（ESI） in multi reaction monitoring（MRM） mode，and finally quantified by the external standard method．The correlation analysis and independent sample t-test were performed for the contents of the 33 target constituents．The results showed that the optimal extraction conditions were as follows：a methanol volume fraction of 70%，a liquid to material ratio （mL∶g） of 31∶1 and an extraction time of 32 min，under which the extraction yield for quercetrin reached 3.77 mg/g．The standard curves for 33 target constituents showed good linearity in the corresponding range with their correlation coefficients（r） not less than 0.999 0．The limits of detection（LODs） and limits of quantitation（LOQs） were in the range of 0.13－66.85 ng/mL and 0.42－222.83 ng/mL，respectively．The precision，repeatability and stability of this method were excellent．The average recoveries at low，medium and high spiked levels in real samples ranged from 98.0% to 101%，with the relative standard deviations（RSDs） all less than 4.0%．The correlation analysis revealed that the contents of active constituents were associated to a certain extent．A t-test revealed that the contents of various active constituents in the stems branches and leaves of Taxilli Herba differed significantly，and the contents of each constituent，such as quercetin-3-O-glucuronide，hyperin，rutin，isoquercitrin，quercetrin and auicularin，were significantly higher in the leaves than in the stems and branches．The developed method is accurate and stable，which could provide a new method reference for the comprehensive evaluation and overall control on the quality of Taxilli Herba，and a certain reference basis for its rational exploitation．关键词：Taxilli Herba;ultra-fast liquid chromatography－triple quadrupole－linear ion trap mass spectrometry;independent samples t-test;correlations;Box－Behnken response surface methodology;active constituents
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发布时间：2023-01-04 - 摘要：A novel near-infrared fluorescent probe for the detection of nitric oxide（NO） was synthesized in this paper，with o-phenylenediamine-modified [c][1, 2, 5] benzothiadiazole-5， 6-diamine as NO recognition group and electron acceptor，fluorene derivative as fluorescent group and electron donor．The spectroscopic properties and feasibility of the probe for the detection of NO were investigated by UV spectroscopy and fluorescence experiments．The probe can form a benzotriazole structure after reacting with NO，and the fluorescence emission spectrum was enhanced in the near-infrared region significantly according to the enhancement of the intramolecular charge transfer（ICT） effect．Compared with the conventional enhanced or quenched nitric oxide fluorescent probes，the developed fluorescent probe exhibited a low background fluorescence but strong anti-interference ability through the proportional fluorescence，which could realize the near-infrared fluorescent analysis and detection of NO．The fluorescent probe also showed an excellent anti-interference ability to the other coexisting interfering species，with no reaction to the reactive oxygen and reactive nitrogen species．Furthermore，the probe displayed a rapid and sensitive fluorescence response to the varieties of NO concentrations with a linear range of 0－10 μmol/L and a detection limit of 28.88 nmol/L．The results of selectivity experiments showed that only NO could significantly trigger the probe fluorescence response，and the probe has good specificity and anti-interference for the detection of NO．The ratiometric fluorescent probe prepared in this paper realized the near-infrared fluorescence analysis and detection of NO with a low background fluorescence but strong anti-interference ability，which could be applied to the detection of NO in biological samples．关键词：nitric oxide（NO）;fluorescent probe;ratio type;fluorescence detection;organic small molecule probe
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发布时间：2023-01-04 - 摘要：In this paper，a novel sensitive fluorescent probe［Ir（bzq）2（L1）］（PF6）（bzq，i.e. benzoquinoline，and L1，i.e. 4'-methyl-2，2'-bipyridine-4-formaldehyde oxime） was synthesized and characterized in detail．After adding hypochlorite（ClO-） in ［Ir（bzq）2（L1）］（PF6） system，the fluorescence of this complex was significantly enhanced because the oxime group on L1 as the reaction site was transformed into the carboxylic acid，resulting in a bright visible orange-yellow light from dark brown under a 365 nm ultraviolet lamp．Under the optimum conditions，the fluorescence intensity of ［Ir（bzq）2（L1）］（PF6） probe showed a good linear relationship with hypochlorite in the concentration range of 0.1－210 µmol/L，with a detection limit of 3.08 nmol/L．The selective and competitive experiments revealed that this probe showed better selectivity and sensitivity for ClO- than that for other ions．The proposed method was applied to the detection of ClO- in local river samples with satisfactory recoveries of 92.4%－103%，suggesting that the fluorescent probe could be used for analysis of ClO- in practical samples．关键词：fluorescent probe;iridium complex;hypochlorite;synthesis;application
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发布时间：2023-01-04 - 摘要：A method for the structural identification of polyglycerol fatty acid esters was developed by Fourier transform ion cyclotron resonance mass spectrometry（FT－ICR－MS），nuclear magnetic resonance hydrogen（1H NMR） spectrum and gas chromatography－mass spectrometry（GC－MS）．After the sample was dissolved，it was determined by FT－ICR－MS．According to the accurate molecular ion data，the basic structure of polyglycerol fatty acid ester and the polymerization degree of glycerol were inferred．The basic structure of polyglycerol fatty acid ester and the polymerization degree of glycerol were further verified by 1H NMR．After hydrolysis，the fatty acid part was methylated，then extracted with n-heptane，and finally determined by GC－MS．Based on the above results，the structure of polyglycerol fatty acid ester was determined．This study provides a new idea and method for the structural identification of polymers.关键词：Fourier transform ion cyclotron resonance mass spectrometry（FT－ICR－MS）;nuclear magnetic resonance（NMR）;gas chromatography-mass spectrometry（GC－MS）;polyglycerol fatty acid esters caramel pigment;structural identification
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发布时间：2023-01-04 - 摘要：In view of the lack of accurate and efficient high-throughput detection techniques in metabolomics research of gill target organs in fish，an analysis method based on ultra-high performance liquid chromatography－quadrupole time-of-flight mass spectrometry（UPLC－QTOF MS） was established and optimized．In order to improve the extraction effect of metabolites in the sample，the total peak area，number of metabolites，relative standard deviations（RSDs） of relative peak area，and response values of glucose，L-leucine，citric acid，and other three representative endogenous metabolites with different species and polarities were used as indicators，and the effects of different experimental conditions on the extraction coverage and stability of metabolites in gill tissue were investigated．The results showed that the best extraction effect could be obtained by adding pre-cooled methanol－water（4∶1） at a sample－reagent ratio（mg∶μL） of 1∶16 to the gill tissue ground at low temperature，and holding for 30 min at －20 ℃，then centrifuged to extract gill tissue samples．Meanwhile，the chromatographic and mass spectrometry parameters in the data acquisition process were optimized，further improving the separation effect and signal intensity of metabolites．Methodological investigations were carried out by using quality control（QC） samples interspersed in the assay sequence．The results showed that this metabolomics analysis posessed good instrumental precision，method precision，and sample stability．The RSDs for the relative peak areas of the six representative metabolites with different polarities were lower than 10%，which meets the requirements for metabolomics research of fish gill target organs．The results provide an technical support for the metabolomic study of fish gill target organs．关键词：metabolomics;sample pretreatment;fish;gill;ultra-high performance liquid chromatography－quadrupole time-of-flight mass spectrometry（UPLC－QTOF MS）
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发布时间：2023-01-04 - 摘要：The accurate and rapid quantitative detection on cancer biomarkers is of great significance to early diagnosis and prognosis monitoring，especially for prostate cancer，the most common malignant tumor in male genitourinary system，its prostate specific antigen（PSA） is the most important early detection index for blood serum．Herein，an electrochemiluminescence resonance energy transfer immunosensor（ECL－RET） was constructed for the ultrasensitive detection of PSA in serum，with quaternary Cu－Zn－In－S nanocrystals（NCs） as the ECL donor and gold nanostars（AuNSs） as the acceptor．The immunosensor exhibited a very strong initial ECL signal and a low ECL potential. The multi-walled carbon nanotubes（MWNTs） attached on the substrate not only accelerated the reaction between NCs and S2O
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发布时间：2023-01-04 - 摘要：A method based on liquid chromatography－tandem mass spectrometry with magnetic graphene oxide dispersive solid phase extraction was developed for the determination of 14 kinds of endocrine disruptors in PVC children products．The samples were soaked in simulated sweat and simulated saliva，and the endocrine disruptors in migration fluid were enriched by magnetic graphene oxide dispersive solid phase extraction，determined by liquid chromatography－tandem mass spectrometry，and quantified by matrix external standard method．The results showed that 14 kinds of endocrine disruptors could be enriched and purified by a 15 min adsorption of 10 mg magnetic graphene oxide，and followed by a 15 min desorption of 3 mL acetone containing 1% formic acid．There were good linear relationships for the 14 analytes in the respective concentration ranges，with their correlation coefficients of 0.990 1－0.999 2．The limits of detection and limits of quantitation were in the range of 0.1－0.5 µg/L and 0.3－1.5 µg/L，respectively．Meanwhile，the spiked recoveries ranged from 80.2% to 105%，with relative standard deviations（RSDs） of 1.0%－6.8%．The method is simple，rapid and reproducible，and it could be used to determine the migration of endocrine disruptors in PVC children products．关键词：liquid chromatography－tandem mass spectrometry（LC－MS/MS）;magnetic graphene oxide;endocrine disruptors;migration;PVC children products
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发布时间：2023-01-04
Scientific Papers
- 摘要：In this work，an ultrahigh performance liquid chromatography tandem time-of-flight mass spectrometry（UPLC－Q－TOF MS） with chemometric method of automatic untargeted data analysis software（AntDAS） was developed to analyze the flower samples of Elaeagnus angustifolia L.．Flowers from four periods，i.e．initial bloom stage（25% of flowers），pre-full bloom stage（70%－80% of flowers），full bloom stage（100% of flowers） and the ending of the bloom stage（flowers began to wither） were collected at the location of Yinchuan，China．All samples were immediately placed into liquid nitrogen after collection，and transformed into the laboratory．Then，each flower sample was grounded to powder with a grinder．About 20 mg samples were weighted and put into a 2 mL tube，then added with 1.5 mL extraction solution（a mixture of methanol and water with volume ratio of 7∶3） to perform the metabolite extraction．A 30 min ultrasonic extraction was utilized，followed by a 15 min centrifugation at 13 000 r/min．Eventually，about 3 µL was injected into an AB SCIEX Triple TOF 5600 + MS instrument，which was connected with a Waters ACQUITY UPLC I－Class PLUS UPLC．Metabolites were separated with a chromatographic column of Waters ACQUITY UPLC BEH C18（2.1 mm × 100 mm，1.7 μm）．The mobile phase consisted of water and acetonitrile，both of which were added with 0.1% formic acid．The acquired data files were directly imported into AntDAS for automatically performing extracted ion chromatogram（EIC） construction，EIC peak detection，and peak registration to screen features that show significant differences among various flowering stages．At last，compound identification was performed by the AntDAS on the basis of the screened features．A total of 19 metabolites were identified based on the above-mentioned data analysis workflow，among which 12 metabolites were further confirmed by standards，including L-lysine，L-histidine，glutamine，L-methionine，L-tyrosine，phenylalanine，L-tryptophan，N-methyl-L-proline，trans-4-coumaric acid，isorhamnetin-3-O-rutinoside，trans-ferulic acid and ormosanine．Results from both principal component analysis and hierarchical cluster analysis indicated that flowers of Elaeagnus angustifolia L．from different flowering stages can be clearly separated．The heatmap analysis suggested that compounds from various flowering stages show significantly different expression levels．For example，majority of amino acids（L-tryptophan，L-lysine，L-histidine，L-tyrosine and L-methionine） were expressed at higher levels during the full bloom and the ending of the bloom stages when compared with the initial bloom and the pre-full bloom stages．The study may be helpful for the quality evaluation of flowers of Elaeagnus angustifolia L.．Additionally，the developed strategy provides a new solution for current plant-related research works.关键词：Elaeagnus angustifolia L. flowers;AntDAS software;metabolics;chemometrics;ultrahigh performance liquid chromatography tandem time-of-flight mass spectrometry（UPLC－Q－TOF MS）;component analysis
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发布时间：2023-01-04
Scientific Paper
- 摘要：Near-infrared spectroscopy is widely applied in the quality monitoring process of traditional Chinese medicine since it features with rapid detection，and making no damage to the samples and no pollution to the environment in the meantime. In order to realize the rapid prediction of the target ingredients of Antai Pills，a new near-infrared spectroscopy modeling method was proposed，which combines scalable one-pass self-representation learning（SOP－SRL） with partial least-squares（PLS）. Taking ferulicacid，baicalin and wogonoside in Antai pills as the research objects，the representative bands selected by SOP－SRL were compared with three band selection algorithms，such as correlation coefficient method（CC），regularized self-representation algorithm（RSR） and sparse subspace clustering （SSC）. Then，the quantitative model was established by PLS. The evaluation criteria of the model are root mean squares error of cross validation（RMSECV），corrected determination coefficient（
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发布时间：2023-01-04 - 摘要：A gas chromatography－tandem mass spectrometry（GC－MS/MS） combined with QuEChERS plus prepositive internal standard was developed for the simultaneous detection of 37 pesticide residues in tea. The target pesticides included 14 organophosphorus pesticides，10 organochlorine pesticides，8 pyrethroid pesticides and 5 organic heterocyclic pesticides. The effects of different extraction solvents，water amounts and internal standard adding approaches on extraction were studied. The matrix effects of 37 pesticides in different types of tea were also explored. The optimal experimental conditions were as follows：firstly，the tea samples were soaked for 30 min with 10 mL water after adding heptachlor epoxide as internal standard，then the target pesticides were extracted ultrasonically using 20 mL acetonitrile for 20 min，followed by adding QuEChERS extract pouch（containing 6 g magnesium sulfate and 1.5 g sodium acetate）. After vortexing evenly and centrifugation，10 mL of the supernatant was separated and transferred into QuEChERS purge tube which contained a mixed sorbent of 1 200 mg magnesium sulfate，400 mg primary secondary amine（PSA），400 mg C18 and 400 mg graphitized carbon black（GCB）. The mixtures were vortexed evenly and centrifugated. Then 2 mL of the purified solution was concentrated by nitrogen blowing at 40 ℃ until the solution was nearly desiccated. After that，1 mL ethyl acetate was used to redissolve the residues. Finally，the target pesticides were detected by GC－MS/MS in multiple reaction monitoring（MRM） mode，and quantified by the internal standard method with matrix matching standard curve. The results showed that the use of prepositive internal standard had a better recovery result than the use of postpositive internal standard. Chromatogram signals of most pesticides in green tea，black tea，white tea and dark tea matrices were enhanced distinctly. Under the optimized conditions，good linear relationships were observed for the 37 pesticides，and the correlation coefficients（r2） were greater than 0.99. The limits of detection（LODs） and the limits of quantitation（LOQs） were in the range of 0.2－15.7 μg/kg and 0.7－52.2 μg/kg，respectively. The recoveries for 37 pesticides at three spiked levels（the LOQ，2 times the LOQ and 10 times the LOQ） ranged from 70.2% to 120%，with relative standard deviations（RSDs） of 1.1%－11%. This method has the features of simple operation，high accuracy，high efficiency and low cost，which could be applied to the routine detection of pesticide residues in tea.关键词：gas chromatography－tandem mass spectrometry（GC－MS/MS）;QuEChERS;prepositive internal standard;tea;pesticide residues
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发布时间：2023-01-04 - 摘要：An ultra high performance liquid chromatography－tandem mass spectrometry（UPLC－MS/MS） with dispersive solid phase extraction（dSPE） was developed for the simultaneous determination of six alkaloids in Ervatamia officinalis Tsiang．Effects of the dSPE experimental conditions on the extraction efficiency for six alkaloids were investigated by single factor．The optimum conditions showed that the ratio of solid to liquid（g∶mL） was 1∶20 with 1% ammonia methanol as solvent，and the amount of PSA and NH2 mixed adsorbent was 200 mg．After dSPE extraction，the sample was analyzed by UPLC－MS/MS with acetonitrile and 0.1% ammonium formate as mobile phases．Results showed that there were good linear relationships for six alkaloids in the range of 1－100 mg/L，with their correlation coefficients not lower than 0.983 7．The limits of detection and limits of quantitation were in the range of 0.05－0.10 mg/L and 0.15－0.35 mg/L，respectively．The recoveries at three spiked levels of 1，10 and 50 mg/L ranged from 93.2% to 98.1%，with relative standard deviations（RSDs） not more than 2.9%．The method was used for the determination of six alkaloids in the samples from 6 habitats，with their contents of 0.07－0.86 mg/g．The spiked recoveries were in the range of 91.5%－98.6%，with RSDs of 1.1%－2.9%．The method is accurate，sensitive，rapid and simple，and it could meet the requirements for detection of the alkaloids in Ervatamia officinalis Tsiang.关键词：Ervatamia officinalis Tsiang;alkaloid;dispersive solid phase extraction;ultra high performance liquid chromatography－tandem mass spectrometry
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发布时间：2023-01-04 - 摘要：A gas chromatography－triple quadrupole mass spectrometry was developed for the rapid determination of pyroxasulfone residues in animal-derived foods．Pyroxasulfone residues in pork，pig liver，chicken，chicken liver，milk and eggs were extracted with acetonitrile，and cleaned up with primary-secondary amine，stearyl bonded silica gel and anhydrous magnesium sulfate as dispersive solid-phase extraction sorbent．After centrifugation，the supernatant liquid was nitrogen-blowed to dryness．After redissolved with acetone and filtered，the analyte was detected by gas chromatography－triple quadrupole mass spectrometry，and quantified by external standard method．The instrument conditions，extraction solvents and purification method were optimized in the experiment，and the optimal pretreatment method and instrument conditions were obtained．The detection effects of pyroxasulfone by triple quadrupole liquid chromatography－mass spectrometry and triple quadrupole gas chromatography－mass spectrometry were compared．The results showed that the response of pyroxasulfone on triple quadrupole liquid chromatography－mass spectrometry was poor，and the detection sensitivity could not meet the requirements of relevant regulations，while the detection effect of pyroxasulfone by triple quadrupole gas chromatography－mass spectrometry was excellent，which could meet the detection requirements．In addition，the extraction effects of hexane，acetone，ethyl acetate，acetonitrile and acidic acetonitrile as extraction solvents were compared，and the results showed that acetonitrile was the most suitable extraction solvent．The matrix effect of the sample was investigated，and it was found that the matrix effects of pyroxasulfone in the six matrices were less than 20%，which were a weak matrix effect without compensation. Under the optimal conditions，the calibration curve was linear in the range of 0.5－100 µg/L with correlation coefficients of 0.999 5． The limit of quantitation was 0.001 mg/kg. The average recoveries for blank samples at low，medium and high spiked levels ranged from 85.8% to 106%，with relative standard deviations（n = 6） of 3.1%－6.8%．This method was used to determine 50 animal-derived foods，in which pyroxasulfone residues were detected in one beef sample and one mutton sample．The method is simple，rapid and sensitive，and it could meet the requirements for detection of pyroxasulfone residue in animal-derived foods.关键词：pyroxasulfone;animal-derived foods;gas chromatography－triple quadrupole mass spectrometry
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发布时间：2023-01-04 - 摘要：A molecularly imprinted electrochemical sensor based on chitosan modified layer was fabricated for the detection of fenthion．For the first time，the adsorption enrichment of the modified electrode to the probe ions was used to improve the sensitivity of the molecular imprinted sensor．The response process of the sensor was characterized by electrochemical impedance spectroscopy and cyclic voltammetry．The experimental conditions such as elution，resorption and probe enrichment time were optimized．The sensitization effect of chitosan on the "gate control effect" measurement mode was investigated．Under the optimized conditions，the detection range of the sensor for fenthion was 1－10 000 pg/mL，with a detection limit of 0.35 pg/mL．The sensor was successfully used for the determination of fenthion in vegetables and fruits samples．The spiked recoveries ranged from 99.0% to 109%，with relative standard deviations of 1.9%－2.9%．关键词：chitosan;molecular imprinting;fenthion;signal enhancement;gating effect
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发布时间：2023-01-04 - 摘要：Photocathode-based sensors possess the advantages of high selectivity and anti-interference in real sample detection，though photocathode produces low photocurrent signal and gives rise to poor sensitivity．Herein，a novel silver bromide-silver-carbon nanotubes（AgBr－Ag－CNTs） composite was synthesized by solvothermal method，and was characterized by scanning electronic microscopy，X-ray diffraction and X-ray photoelectron spectroscopy．Because reduced Ag has revealed localized surface plasmon resonance effect（LSPR），it can amplify light absorption efficiency．Furthermore，CNTs could optimize the electric field near metallic Ag，strengthen light absorption and improve the separation efficiency of photo-generated carriers．Thus AgBr－Ag－CNTs displayed an better cathodic photoelectrochemical activity，compared with AgBr or AgBr－Ag．With K3［Fe（CN）6］ as photoelectron acceptor，the photocurrent response could be further increased．To develop the practicality of AgBr－Ag－CNTs，an ochratoxin A（OTA） aptasensor was constructed by using AgBr－Ag－CNTs as photocathodic sensing interface，an aptamer as target recognition site，and K3［Fe（CN）6］ as photoelectron acceptor．Since the aptamer/OTA complex has a rigid structure with weak conductivity，it could effectively block the absorption of light with the sensing interface，inhibit the transfer of photoelectrons toward electron receptors，and reduce the photocurrent signal．Based on the changed photocurrent as signal，the sensor showed a wide linear response from 4.0 pg/mL to 2.5 ng/mL（r2 = 0.994） and a low detection limit of 1.5 pg/mL．It was used for detection of OTA in real samples，with recoveries of 92.0%－108%．This work provided a novel photoelectrochemical method for OTA detection，with high sensitivity，specificity and good anti-interference．关键词：AgBr－Ag－CNTs;photocathode sensor;aptamer;ochratoxin A
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发布时间：2023-01-04
Experimental Techniques and Methods
- 摘要：In this paper，an iterative shrinkage window-bootstrapping soft shrinkage（ISWBOSS） algorithm was proposed to address problems of poor prediction performance of the calibration models based on near-infrared（NIR） spectroscopy due to their redundant variables in NIR spectra．The variables was divided by windows in the method，and the windows were randomly selected，in which the sub-models were built with the variables．The soft shrinkage of the variable space was gradually achieved by calculating the normalization of the regression coefficients of the variables in the window，and continuing the weighted sampling as weights．Meanwhile，the window size was continuously shrunk during the iterative process to perform an accurate search of the feature variables．It was validated on a corn dataset，and compared with the partial least squares models established by the full-spectrum method，genetic algorithm，competitive adaptive reweighted sampling，and bootstrapping soft shrinkage approach．The results showed that the new method had significant advantages in terms of both accuracy and stability．Taking corn protein content prediction as an example，the root mean square error of prediction of ISWBOSS was reduced from 0.041 8 to 0.010 3，compared with the bootstrapping soft shrinkage approach．Moreover，the new method required fewer iterations and higher operational efficiency to reach the optimal model，which was a guideline for improving the performance of NIR spectral calibration models．关键词：variable selection;iterative shrinkage window;near-infrared spectroscopy;partial least squares;model calibration
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发布时间：2023-01-04
Experimental Techniques and Method
- 摘要：Graphitic carbon nitride，an emerging two-dimensional honeycomb nanomaterial，is composed of π-conjugated graphitic planes via sp2-hybridized of C and N through the interaction of lone pair electrons on the PZ orbital. This highly delocalized conjugated structure endows it multiple interactions with target molecules or ions，such as hydrogen bonds，π－π interaction，hydrophobic effects，and electrostatic interactions. Thus，graphitic carbon nitride is regarded as a potential adsorbent. However，the aggregated layer-by-layer structure resulted in its limited surface area（< 10 m2/g）. Compared with bulk sample，mesoporous graphitic carbon nitride with typical pore size ranging from 2－50 nm possesses larger surface area and higher pore volume，which could provide more active sites exposed on its surface. The synthesis of mesoporous graphitic carbon nitride and its application in the field of environmental sanitation are herein summarized，and its development trend is also prospected.关键词：graphitic carbon nitride;mesoporous graphitic carbon nitride;environmental sanitation;review
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发布时间：2023-01-04
Review
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