最新刊期
卷 40 ， 期 10 ， 2021
- 摘要：A competitive time-resolved fluorescence（TRF） lateral flow assay for 17β-estradiol（E2） was established with 17β-estradiol－BSA（E2－BSA） coupled persistent luminescence particles（PLPs） as fluorescence donor and colloidal gold（CG）-labelled antibody as fluorescence receptor，based on immune recognition and fluorescence resonance energy transfer principle．In this method，the PLPs with long persistent luminescence but large size of micron were applied as the fluorescence signal source，and its non-migration property on nitrocellulose membrane was used to fix the E2 competitor in the test zone，thus the contradiction between the limitation that the signal material of traditional test paper must be nanometer size and the short luminous lifetime of small PLPs was skillfully solved．In addition，a low-power UV lamp was used as the light source to excite the PLPs，and the continuous shooting function of smart phone was used to realize TRF－mode fluorescence acquisition，effectively removing the fluorescent background interference from the test strips and improving the signal-to-noise ratio．The detection limit of this method was 0.1 ng/mL，which was about two orders of magnitude more sensitive than those of colloidal gold and HPLC－FLD method．The detection limit of this method was 0.1 ng/mL，which was about two orders of magnitude more sensitive than that of colloidal gold．The method showed good selectivity and could perform detection in 30 min．Using this method to detect E2 in a water sample and the results were consistent with that of HPLC-FLD method.关键词：time-resolved fluorescence;lateral flow assay（LFA）;17β-estradiol;fluorescence resonance energy transfer;persistent luminescence particle
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发布时间：2023-02-13 - 摘要：An on-line solid-phase extraction/ultra performance liquid chromatography－tandem mass spectrometric（SPE/UPLC－MS/MS） method was developed for the determination of twenty-six quinolone residues in honey．Firstly，the samples were extracted with 1% formic acid solution－methanol（10∶90），then rapidly purified by solid-phase extraction using an Oasis PRiME HLB cartridge．During the process，the key factors，such as the extraction solvent and purification method were optimized individually．The analytes were separated on an Agilent Eclipse Plus RRHD C18 column（2.1 mm × 50 mm，1.8 µm） by gradient elution，using water containing 0.1% formic acid and acetonitrile as the mobile phases．The target compounds were analyzed with electrospray ion source in positive ion mode under dynamic multi-reaction monitoring（dMRM） mode，and quantified by internal standard method．Results showed that there were good linear relationships for 26 quinolones in their respective concentration ranges with correlation coefficients（r2） more than 0.997．The limits of quantitation（LOQ） were in the range of 0.5－2.0 μg/kg．The average recoveries for 26 quinolones at low，medium and high spiked levels ranged from 79.5% to 110%，with relative standard deviations（RSD，n = 6） of 2.0%－12%．The developed method was rapid and accurate，which was suitable for the simultaneous screening and quantitative determination of 26 quinolones in honey．关键词：on-line solid-phase extraction;ultra performance liquid chromatography－tandem mass spectrometry;quinolones;honey
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发布时间：2023-02-13 - 摘要：3-Phenoxybenzoic acid（3-PBA），as the most common metabolite of pyrethroid pesticides，is typically employed as the risk indicator for pyrethroid pesticides exposure. Antibody-based immunoassay has the advantages of rapidity，high sensitivity and easy operation，which is considered as a promising tool for the risk exposure assessment on hazardous chemicals in environment，food stuffs and human body fluid samples. Nanobody（Nbs） is the variable domain of heavy chain-only antibody（VHH） derived from heavy chain antibodies（HCAbs） of camelidae or new antigen receptor（NAR） of shark，which are naturally lack of light chain. Unlike conventional antibodies，Nbs have high binding affinity with only a single domain，avoiding the complex combination of heavy and light chains during recombinant expression，which would sometime lead to the low solubility and stability of genetically engineered antibody fragments. Therefore，Nbs are easily expressed in soluble form，and have similar affinity with its natural structure. And Nbs have been reported to have excellent thermostability and organic solvent tolerance，which is benefit to simplify the pretreatment step. Thus，Nbs are considered as an ideal tool for developing rapid immunoassays. In this work，with the aim to develop a sensitive immunoassay for monitoring the metabolite of pyrethroid pesticides 3-PBA in water and human urine samples，the biotinylated 3-PBA Nbs using biotin N-hydroxysuccinimide ester（biotin－NHS） were prepared. To further amplify the signal of immunoassay，a polymeric horseradishperoxidase conjugated streptavidin（polyHRP－SA） was also introduced to develop a biotin－avidin system based indirect competitive enzyme-linked immunosorbent assay（icELISA）. The assay conditions were carefully optimized as follows：the coating antigen concentration was 125 ng/mL，the dilution ratio of biotinylated 3-PBA to Nbs was 1∶2 000，PBST with an ion concentration of 40 mmol/L，a pH 6.4 and a Tween－20 concentration of 0.005% （by volume） was optimal working buffer system，the dilution ratio of polyHRP－SA was 1∶4 000. The developed icELISA showed a half maximal inhibitory concentration（IC50） of 1.7 ng/mL，a linear range of 0.37－7.4 ng/mL and a limit of detection（LOD） of 0.15 ng/mL. The proposed Nbs-based icELISA was applied in the detection of 3-PBA in water and human urine samples. For water samples such as lake water， reservoir water，tap water and drinking water，the matrix effects could be easily eliminated by simply filtering and then used for icELISA without further dilution，while for the human urine samples，high temperature acid hydrolysis and solid phase extraction（SPE） purification are benefit to reduce the matrix effects. The spiked recoveries for human urine and water samples were in the range of 87.0%－127% and 78.0%－113%，respectively，with relative standard deviations（RSD） not more than 10%. Results indicated that the proposed method was sensitive and easy to operate，which could be used as an ideal tool for screening 3-PBA residues in environmental and biological samples.关键词：3-phenoxybenzoic acid（3-PBA）;pyrethroid pesticides;nanobody（Nb）;biotinylation;signal amplification
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发布时间：2023-02-13 - 摘要：Extra virgin olive oil is favored by consumers for its high nutritional value，but its prices is relatively expensive．In order to increase profits，some illegal merchants have taken some concealed means to mix refined olive oil into extra virgin olive oil，or pass off refined olive oil as extra virgin olive oil to cheat consumers．At present，domestic studies on adulteration of olive oil mainly focus on the adulteration of olive oil with other edible oils，and few studies involve in grade identification of extra virgin olive oil and low-grade olive oil．Foreign studies on the identification of olive oil grades are mainly based on spectral technology，while the spectral method could only provide the relevant information of the whole fingerprint characteristics，but not the information of its specific components．Therefore，it is significant to establish a method to distinguish the grades of extra virgin olive oil and low-grade olive oils based on the characteristic components in olive oil．In this paper，a method was established to distinguish the grade of olive oil based on the content analysis of fatty acids combined with chemometrics．Extra virgin olive oil and refined olive oil with confirmed properties were used as test set．Fatty acids contents in the two grades of olive oil were determined by gas chromatography（GC） using SP－2560（100 m × 0.25 mm，0.2 μm） column．Olive oil grade discrimination model was established by three chemometrics，i.e. primary component analysis（PCA），hierarchical cluster analysis（HCA） and partial least squares－discrimination analysis（PLS－DA）．Results showed that，PCA could successfully distinguish extra virgin olive oil and refined olive oil，and HCA could also effectively identify two grades of olive oil．Through PLS－DA，six characteristic components with variable importance in the projection（VIP） greater than 1 were selected as follows：C23∶0，C18∶2n6t，C24∶0，C18∶1/C18∶2，C20∶1 and C18∶1n9c. Meanwhile，98 olive oil samples with unknown properties were taken as the validation set，and cross validation（CV） was carried out on the established olive oil grade discrimination model．The model prediction evaluation value（Q2） and correlation coefficient（R2） were greater than 0.96．The results indicated that the established model of olive oil grade discrimination and prediction was reliable．Therefore，analysis of fatty acids and multiple element contents combined with chemometrics could be used to identify the grades of extra virgin olive oil and refined olive oil．关键词：fatty acids;extra virgin olive oil;refined olive oil;chemometrics;grade identification;gas chromatography
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发布时间：2023-02-13 - 摘要：In this study，a method was developed for simultaneous determination of 16 organophosphate esters（OPEs） in medical masks by ultra-high performance liquid chromatography－tandem mass spectrometry（UPLC-MS/MS）．In addition，the extraction and purification process for 16 OPEs was optimized．Specifically，three different extracting solvents including dichloromethane－n-hexane（1∶1），dichloromethane－acetonitrile（1∶1） and methanol，coupled with two purification processes，were compared. Meanwhile，the mask samples were ultrasonically extracted three times with methanol，then purified with ENVI－18 cartridges using 6 mL acetonitrile containing 25% dichloromethane as the eluent．The analytes were separated on a Acquity UPLC BEH C18 column by gradient elution using 5 mmol/L ammonium acetate and methanol as the mobile phases，then analyzed in electrospray ionization positive（ESI+） mode under the multiple reaction monitoring（MRM） mode，and finally quantified by internal standard method．Results indicated that the limits of detection（LOD，S/N = 3） for 16 OPEs in mask were in the range of 0.004 60－1.03 ng/dm2，while the limits of quantitation（LOQ，S/N = 10） were 0.015 2－3.43 ng/dm2．The average recoveries for 16 OPEs in medical mask at three spiked levels of 5， 20 and 40 ng ranged from 68.8% to 140%，with relative standard deviations（RSD） of 0.70%－18%．These results indicated that the established method was suitable for the determination of OPEs in medical mask samples．The method was applied to the quantitation of 16 OPEs in forty-two medical mask samples．The total concentrations of 16 OPEs were in the range of 6.60－2 387 ng/dm2，with a median concentration of 34.2 ng/dm2．The detection frequencies for twelve OPEs were higher than 50%．Tri-phenyl phosphate（TPHP） and tri（1-chloro-2-propyl） phosphate（TCIPP） were the most abundant OPEs，with concentrations of 0.131－2 274 ng/dm2 and 0.370－79.8 ng/dm2，respectively．Considering that the concentration of each analyte was relatively low，it is speculated that the OPEs in medical mask may be adsorbed from the air or transferred from plastic packaging during the manufacturing or packaging process．关键词：organophosphate ester;ultra-high performance liquid chromatography－tandem mass spectrometry;medical mask;textile;flame retardant
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发布时间：2023-02-13 - 摘要：Bisphenol A（BPA） is an endocrine disrupting substance commonly used in the manufacture of plastics，which is harmful to human health．In this paper，an electrochemical sensor based on polydopamine-coated zirconium-based metalorganic framework（Zr－MOF－PDA） was constructed to detect BPA．Under the alkaline conditions，the Zr－MOF－PDA composite was synthesized with Zr－MOF（4-carboxyphenylporphyrin as the ligand） as the supporter material and dopamine as the monomer．The composite was characterized by infrared spectroscopy，thermogravimetric analysis and scanning electron microscopy，and then modified onto the surface of glassy carbon electrode（GCE） for the determination of BPA．The electrochemical behaviors of the modified electrodes were investigated by cyclic voltammetry，chronocoulometry and differential pulse voltammetry．The cyclic voltammetry oxidation peak current values of Zr－MOF－PDA/GCE，Zr－MOF/GCE and bare GCE were 107.3，93.28 and 77.51 μA，respectively，and their electrode effective surface areas were 0.514，0.667 and 0.467 cm2，respectively．The experimental results showed that the Zr－MOF－PDA/GCE had a good conductivity and a large effective surface area．The differential pulse voltammetry response current of the Zr－MOF－PDA/GCE for BPA were 1.6，2.0 and 2.8 times of those of PDA/GCE，Zr－MOF/GCE and bare GCE，respectively．The Zr－MOF as a carrier material had an excellent conductivity and a large specific surface area．PDA contained a large amount of amine and catechol groups．Therefore，the Zr－MOF－PDA exhibited a high adsorption capability for BPA due to the hydrogen-bond interaction between Zr－MOF－PDA and BPA，which improved the detection sensitivity of the BPA electrochemical sensor．The electrochemical detection conditions were also studied，and the optimal conditions were as follows：concentration of Zr－MOF－PDA：3 mg/mL，adsorption time：6 min，and pH value of the phosphate buffer：9.0．Under the optimal conditions，the Zr－MOF－PDA/GCE showed a good linear relationship for the detection of BPA in the range of 0.01－1.4 μmol/L，and the linear regression equation was I（μA） = 0.283 9 C（μmol/L） + 0.02（r2 = 0.993 6）．The detection limit（S/N = 3） for BPA was 0.004 μmol/L．With good selectivity，stability and reusability，the proposed method was successfully used in the detection of BPA in river water，milk and plastic bottles．The recoveries ranged from 98.4% to 103%，with relative standard deviations（RSD） of 3.4%－4.4%.关键词：metal organic framework;polydopamine;electrochemical sensor;bisphenol A（BPA）;detection
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发布时间：2023-02-13 - 摘要：An ultra-performance liquid chromatography－mass spectrometry（UPLC－MS/MS） with high kinetic energy grinding was established for the rapid detection of ketamine and its metabolites in hair．The effects of cleaning procedures and extraction methods on the detection of ketamine and its metabolites were investigated，respectively，and the best experimental scheme was determined．50 mg hair was washed twice with 0.1% sodium lauryl sulphate，ultrapure water and acetone．Then 20 mg of the washed hair and 1 mL methanol were placed in a special grinding bottle，and mixed in an oscillating manner．The hair was ground for 3 min at a frequency of 3 000 r/min by the grinding machine．The grinding fluid was ultrasonically disposed for 2 hours，then detected after centrifugation and filtration．There were good linear relationships for contents of ketamine，norketamine and hydroxynorketamine in hair in the range of 0.01－5.0，0.01－5.0，0.05－5.0 ng/mg，with their correlation coefficients higher than 0.99．The extraction recoveries ranged from 86.7% to 106%，and the matrix effects were between 88.1% and 99.6% for all the analytes．The intra-day and inter-day precisions were in the range of 0.72%－4.1% and 1.9%－6.3%，respectively．Meanwhile，50 hair samples of drug addicts were tested in this way．The content data of ketamine，norketamine and droxynorketamine in positive hair were obtained and analyzed．The content distribution of ketamine and its metabolites and the relationship between the contents of ketamine and its metabolites in hair were determined by data analysis．The minimum content of ketamine was 0.30 ng/mg．The content of droxynorketamine was similar to ketamine while the content ratio between norketamine and ketamine ranged from 0.05 to 0.60．These analyses and conclusions could provide a theoretical support and a method reference for the drug-related cases．关键词：hair;UPLC－MS/MS;ketamine and its metabolites;content statistics
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发布时间：2023-02-13 - 摘要：A novel high performance liquid chromatography（HPLC） with hydrophobic deep eutectic solvent（DES） based liquid－liquid microextraction was developed for the separation and determination of triazine（atrazine，terbutryn） and phenylurea（monuron，chlortoluron） herbicides in market packaged soymilk．In this work，a series of new DESs with different molar ratios were synthesized with tetrabutylammonium chloride as hydrogen bond acceptor and hexafluoropropanol as hydrogen bond donor．In addition，the experimental conditions that affect the extraction effect were investigated in detail，including type and amount of DESs，amount of NaCl，vortex time， pH value and temperature．Experimental results showed that，there were good linear relationships for the target analytes in the range of 1.00－500.00 μg/L，with correlation coefficients（r） not less than 0.998 4．The limits of detection（LOD，S/N = 3） and quantitation（LOQ，S/N = 10） were in the range of 0.56－0.95 µg/L and 1.87－3.16 µg/L，respectively．The relative standard deviations for intra-day and inter-day precision were in the range of 0.28%－2.0% and 2.1%－7.5%，respectively．Recoveries for the target analytes in four spiked samples ranged from 86.4% to 117%，with relative standard deviations of 0.13%－5.7%.With the advantages of simplicity，rapidness，short extraction time，low consumption and low experimental cost，this method could be used for the analysis and detection of triazine and phenylurea herbicides in market packaged soy milk．关键词：liquid－liquid microextraction;deep eutectic solvents;triazine herbicides;phenylurea herbicides;soy milk;high performance liquid chromatography
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发布时间：2023-02-13 - 摘要：An indirect competitive chemiluminescence immunoassay（ic-CLEIA） was established for the detection of imidacloprid based on monoclonal antibody．Firstly，the imidacloprid haptens were synthesized with imidacloprid and 3-mercaptopropionic acid，then the haptens were coupled with carrier protein KLH and BSA by active ester method to prepare complete antigens．The complete antigens were used to immunize Balb/c female mice，and their spleen cells were fused with myeloma cells to prepare monoclonal antibody．The conditions of the method such as dilution multiple of coating antigen and antibody，category of buffer，pH of buffer，competition reaction time of primary antibody，and dilution multiple of enzyme-labeled secondary antibody were optimized．The optimum conditions were as follows：a 62.50 ng/mL of coating antigen（dilute 16 000 times），a 103.12 ng/mL of antibody（dilute 64 000 times），a PBS buffer（pH 7.4），a 30 min of the primary antibody competition reaction time and a 7 000-fold dilution of the secondary antibody．Results showed that under the optimal conditions，the detection limit（IC10） of the method was 0.03 ng/mL，IC50 was 0.57 ng/mL，and the linear detection range（IC20－IC80） was 0.083－3.99 ng/mL．The cross-reaction rate with imidaclothiz was 2.2%，and no obvious cross reaction was observed with 5 structural analogues i.e.clothianidin，dinotefuran，acetamiprid，thiacloprid and thiamethoxam．The spiked recoveries for cucumber and apple samples ranged from 82.0% to 112%，with relative standard deviations below 15%．The detection results for real sample has good correlation with those of HPLC method（r2 = 0.989），indicating that the established ic-CLEIA method could be applied to detect imidacloprid residues in food with high specificity and sensitivity．关键词：imidacloprid;monoclonal antibody;indirect competitive chemiluminescence enzyme-linked immunoassay（ic-CLEIA）
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发布时间：2023-02-13 - 摘要：Based on immune genetic algorithm（IGA），an improved immune genetic algorithm（iIGA） was proposed to select the wavelength variables of near infrared spectra．The idea of fixed antibody similarity threshold in the original algorithm was abandoned in the iIGA，which was replaced with adaptive antibody similarity threshold．Meanwhile，the elitist retention strategy and greedy algorithm idea were introduced，making the algorithm carry out local optimization in the right direction．The algorithm was tested on the corn starch and protein content data sets to establish a partial least squares（PLS） analysis model，and compared with IGA，genetic algorithm （GA） and full spectrum method．Results showed that the root mean square error of prediction set （RMSEP） of iIGA was reduced from 0.312 0 to 0.298 0，compared with those of the original IGA algorithm，the prediction accuracy of prediction set was improved by 4.5%．In the prediction of corn protein content，the RMSEP decreased from 0.124 4 to 0.110 3，the prediction accuracy of prediction set increased by 11.3%．A significant test was carried out for the RMSEP values of starch and protein models，respectively，in which F values were 165.22 and 182.05，P values were 9.5 × 10－23 and 4.5 × 10－24，respectively，and P values were less than 0.05．Therefore，iIGA could significantly improve the prediction accuracy of the model．关键词：near infrared spectrum;wavelength selection;improved immune genetic algorithm;analysis model;prediction accuracy
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发布时间：2023-02-13
Scientific Papers
- 摘要：Fluorescence detector has the characteristics of high sensitivity and good selectivity．It is one of the most commonly used detectors in high performance liquid chromatography（HPLC）．In this paper，a multi-wavelength light-emitting diode（LED） induced fluorescence detector was developed based on a confocal optical configuration，which could be applied in detection of variety of substances．The motor multiple calibration positioning technique and light source sliding positioning technique were used to achieve the precise positioning of multiple light sources．And a shared emission optical path was used to simplify the instrument structure and reduce the cost of the instrument．The reliability test on the continuous switching of LED light source for 30 000 cycles showed that the target position errors of the laser ranged within ± 0.2 mm，which realized the accuracy and good repeatability of LED light source positioning，solving the problems of traditional fluorescence detector with complex structure and high price，and LED single wavelength induced fluorescence detector with strong specificity and narrow application range．A mobile phase of methanol and a C18 chromatographic column were used to investigate the baselines of three light sources．Results showed that the developed detector，under excitation light sources of 340，365 and 385 nm ，had baseline noises less than 5.0 × 10－4 FU and a drifts less than 5.0 × 10－3 FU/h．Furthermore，mycotoxins and benzo（α）pyrene were used as probes to evaluate the linearity and sensitivity．Meanwhile，acetonitrile－water－acetic acid（96∶102∶2，by volume），methanol－acetonitrile－water （20∶20∶60） and acetonitrile－water（90∶10） were used as mobile phases for the analysis of ochratoxin A，aflatoxin B1 and benzo（α）pyrene，respectively．The excitation wavelengths of the detector were set at 340，365 and 385 nm，respectively．The concentrations of ochratoxin A，aflatoxin B1 and benzo（α）pyrene showed good linearities （r2 ≥ 0.999 9） in the ranges of 1.0－50.0 ng/mL，0.1－20.0 ng/mL and 0.5－20.0 ng/mL，respectively．The limits of detection were 0.06，0.01 and 0.02 ng/mL，respectively．The repeatability of this detector was investigated，and the result showed that the RSDs （n=11） for sample response values of the three light sources were all less than 1.0%．While using the 340 nm light source as the test condition，the basic performance of the detector under vibration，high temperature and low temperature environments did not changed significantly．The tested results of the detector were comparable in terms of baseline noise，drift and sensitivity，compared with those of the commercially available imported general－purpose fluorescence detectors．With the advantages of simple structure，wide wavelength coverage and good performance，the developed detector showed good application prospects in the detection of mycotoxins and benzo（α）pyrene．关键词：light-emitting diode （LED）;multi-wavelength;fluorescence detector;ochratoxin A;aflatoxin B1;benzo（α）pyrene
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发布时间：2023-02-13 - 摘要：Signing-pen inkblok is an important evidence in the forgery cases which comprise documents，certificates，checks etc．By analyzing the ink types of suspicious handwriting，forensic science experts could recognize suspect's writing behaviors and infer whether the writing utensils are identical．In this paper，a new method for the rapid and nondestructive identification on types of black signing-pen ink by combining hyperspectral imaging（HSI） technique and machine learning was proposed．Primarily，thirty-six collected black signing-pens were numbered in turn through different brands and models，then each of them were used to write their own number three times repeatedly on the same specification of white A4 printing paper as the handwriting for the test.After that，the hyperspectral imager was used to collect the hyperspectral images of the prepared handwritings，and black and white calibration was performed for all the images in order to reduce the effects of dark current of camera and changes of light intensity on the image signal．And then，ENVI was used to read the hyperspectral image information，and eighteen representative region of interest（ROI） were selected manually on the hyperspectral image of each pen's handwriting.In term of the average spectra calculation of the extracted region of interest，a total of 648 average spectra were finally obtained as the sample set．For investigating the effect of different preprocessing methods，Savitzky－Golay smoothing，Z－Score standardization and their combined spectral pre-processing methods were respectively used to preprocess the handwriting original spectra data of 450－950 nm. Furthermore，linear discriminant analysis（LDA） and random subspace method－linear discriminant analysis（RSM－LDA） were respectively adopted to establish two identification models of black signature-pen ink types，and comparing their merits and drawbacks．The experimental results showed that：（1） The hyperspectral images of black signing-pen ink were too consistent to identify，so it was necessary to process by machine learning algorithm；（2） Different pre-processing methods had little influence on the identification accuracy of RSM－LDA model，while LDA model had better identification accuracy after it was combined with spectral pre-processing method；（3） The average classification accuracy rates of LDA model for training set，cross validation set and testing set were 99.54%，98.16% and 84.50% respectively；（4） Compared with LDA model，RSM－LDA model had better classification effect. The average classification accuracy rates for training set，cross validation set and testing set could reach 100%，99.09% and 90.70%，respectively.And the accuracy rates，precision rates and recall rates of each type of samples were all higher than those of LDA model．The AUC value of RSM－LDA model was 0.998 3，which indicated that the RSM－LDA model's performance was remarkably good．To sum up，RSM－LDA model was performed better than LDA model in processing redundant data，possessing anti-interfered，solving over fitting problem，getting better classification accuracy etc.，which exhibited better classification effect and robustness.Therefore，hyperspectral imaging technique combined with RSM－LDA model could be used to achieve the rapid and nondestructive classification and discrimination of different brands and models of black signing-pen ink.关键词：hyperspectral imaging;black signing-pen ink;linear discriminant analysis（LDA） model;random subspace method－linear discriminant analysis（RSM－LDA） model
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发布时间：2023-02-13
Scientific Paper
- 摘要：In order to evaluate the risk of sulfonamides residues in Gizzard Pepsin， a comprehensive analytical method was developed for the qualitative and quantitative determination of nine kinds of sulfonamides in Gizzard Pepsin by ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry（UPLC－MS/MS） in this paper.The sample was extracted by QuEChERS with ultrasonic method，then purified with PRiME HLB．The chromatographic separation was performed on an ACQUITY BEH C18 chromatographic column（2.1 mm × 100 mm，1.7 μm），with 0.1% formic acid－2 mmol/L ammonium acetate aqueous solution and acetonitrile containing 0.1% formic acid as mobile phases by gradient elution.The analytes were detected by electrospray ionization mass spectrometry in positive mode under dynamic multiple reaction monitoring（d－MRM） mode，and quantified by external standard method．Results showed that the nine sulfonamides showed good linearities in the concentration range of 0－50 ng/mL with their correlation coefficients（r2） not less than 0.996 0．The limits of detection（LOD，S/N = 3） and limits of quantitation（LOQ，S/N = 10） were in the ranges of 0.065 4－0.715 7 µg/kg and 0.212 2－2.478 µg/kg，respectively.The recoveries for the analytes at three spiked levels were in the range of 63.2%－88.7%，with relative standard deviations（RSD） of 0.90%－7.1%．The developed method was simple，rapid and accurate，and was applied to the detection on 10 batches of Gizzard Pepsin samples，among which one was found to contain sulfamethoxazole residue．关键词：Gizzard Pepsin;sulfonamides;ultra-performance liquid chromatography－tandem mass spectrometry;QuEChERS;PRiME HLB
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发布时间：2023-02-13 - 摘要：To address the issues of sildenafil adulteration in health-care foods，a direct competition chemiluminescence enzyme immunoassay method（dcCLEIA） was developed for the detection of sildenafil in so-called health-care foods in this work．Horseradish peroxidase（HRP） and luminol were used as signal output system．Based on specific polyclonal antibody，the optimal assay conditions were finalized as follows： the concentration of coating antigen was 41.67 ng/mL，the concentration of antibody was 1.25 μg/mL，the content of Tween－20 in blocking stock solution and washing buffer was 0.05%，the content of methanol in sildenafil dilution solution was 5% and the competitive reaction time was 40 min．Under the optimal conditions，the dcCLEIA method for sildenafil detection was established．The assay showed a half-inhibition concentration（IC50） of 0.17 ng/mL，with a linear detection range（IC20－IC80） of 0.024－1.21 ng/mL，and the limit of detection （LOD，IC10） was 0.008 ng/mL．Meanwhile，the cross-reactivity of dcCLEIA towards tadalafil analogues was less than 0.1%．The recovery test results showed that the average recoveries of the developed dcCLEIA for sildenafil in samples ranged from 82.0% to 114%，with relative standard deviation（RSD） less than 15%．The detection results for random blind samples by dcCLEIA had a good correlation with those of high performance liquid chromatography tandem mass spectrometry（HPLC－MS/MS）．The developed dcCLEIA method was accurate and reliable，and it was suitable for the rapid detection of sildenafil in real samples.关键词：sildenafil;direct competitive chemiluminescence enzyme immunoassay（dcCLEIA）;health-care food;horseradish peroxidase （HRP）
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发布时间：2023-02-13 - 摘要：A method for determination of seven quinolones antibiotics in fishery water was established based on salting-out assisted liquid－liquid extraction（SALLE） coupled with high performance liquid chromatography－tandem mass spectrometry（HPLC－MS/MS）．Water samples were extracted with acetonitrile and layered with salting-out agent of magnesium sulfate．The acetonitrile solution was concentrated under a stream of nitrogen gas．All antibiotics were separated by gradient elution on a Waters Atlantis C18 column（150 mm × 2.1 mm，3.0 μm） with the mobile phases of 0.1%（by volume） formic acid aqueous solution and methanol，and then analyzed with an electrospray ionization source in the positive ion mode．The external standard method was used for quantitative analysis of the antibiotics．Various parameters affecting the extraction process such as pH value of the water sample，type and volume of extraction solvent，type and weight of salting-out agent and vortex agitation time were investigated．Under the optimal conditions，the correlation coefficients（r2） of linear calibration curves were over 0.995 in the corresponding concentration ranges．The limits of detection（LOD） and the limits of quantitation（LOQ） of the method were in the range of 3－10 ng/L and 10－25 ng/L，respectively．Recoveries for the seven quinolones at three spiked levels ranged from 77.8% to 104%，with relative standard deviations（RSD） of 3.1%－10%．The method is simple，sensitive and effective，and could be used for the determination of seven quinolones antibiotics in fishery water.关键词：salting-out assisted liquid－liquid extraction;high performance liquid chromatography－tandem mass spectrometry;quinolones antibiotics;fishery water
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发布时间：2023-02-13 - 摘要：An enzyme-free and label-free fluorescence sensing method for rutin detection was developed based on gold nanoclusters－bovine serum albumin（AuBCs－BSA） fluorescent probe prepared with bovine serum albumin（BSA） as template．The morphology and optical property of the prepared AuNCs－BSA were characterized by transmission electron microscopy（TEM），ultraviolet－visible spectroscopy（UV－Vis） and fluorescent spectroscopy（FL）．The experimental results showed that fluorescence of AuNCs－BSA system was quenched in the presence of rutin as the affinity between BSA and rutin was stronger than that between BSA and AuNCs，resulting in the release of AuNCs from BSA．Under the optimized experimental conditions，the linear range of AuNCs-BSA fluorescent probe for rutin detection was 0－60 µmol/L with a detection limit（S/N = 3） of 0.63 µmol/L．The spiked recoveries of real sample were 99.0%－103% with relative standard deviations less than 3%．The developed fluorescent probe has the advantages of simple preparation，no labeling and high sensitivity，and provides a simple，reliable and effective method for the determination of rutin in practical samples.关键词：rutin;gold nanoclusters;fluorescent probe;enzyme-free and label-free;bovine serum albumin
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发布时间：2023-02-13 - 摘要：A fluorescence probe was designed and synthesized by the reaction between 8-hydroxyquinoline-5-carbaldehyde and benzohydrazide in this work，which was characterized by 1H NMR， 13C NMR and MS，and then employed in the selective fluorescence detection of Mg2+ ion．All experimental results showed that the probe exhibits a good selectivity towards Mg2+ ion by using fluorescence enhancement at 577 nm in DMSO－HEPES buffer solution（20 mmol/L，pH 7.0，95∶5，by volume），with a detection limit for Mg2+ ion as low as 8.2 × 10－8 mol/L．In addition，the probe could also be used to detect Cd2+ ion or Zn2+ ion at the wavelengths of 604 nm and 611 nm．Theoretical calculation demonstrated that，after the formation of a 2∶1 stoichiometric complex between probe and Mg2+ ion，the electron density mainly concentrated around Mg2+ ion，resulting in the fluorescence enhancement due to the smaller energy gap of probe + Mg2+ system.关键词：fluorescence probe;8-hydroxyquinoline;Mg2+ ion;Schiff-base
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发布时间：2023-02-13 - 摘要：A simple，fast and reliable method was developed for quantitative determination of total haloxyfop in plant-derived foods using liquid chromatography coupled to tandem mass spectrometry（LC－MS/MS）．The sample preparation consisted of a dispersive solid phase extraction（dispersive-SPE） method by addition of an alkaline hydrolysis step to release total haloxyfop．The target compound was extracted with acetonitrile，and then purified using anhydrous MgSO4，octadecyl（C18） and graphitized carbon black（GCB）．A mixture of 0.1% formic acid acetonitrile and 0.1% formic acid aqueous solution was used as the mobile phase，followed by binary gradient elution，C18 （2.1 mm × 50 mm，1.7 µm） column separation．The analysis was performed in positive ion mode under multiple reaction monitoring（MRM） mode，and internal standard method was used for quantitative analysis．Results showed that there was a good linear relationship for haloxyfop over the range of 2.5－50 ng/mL with a correlation coefficient（r2） greater than 0.999.At three spiked levels（0.01，0.05 and 0.1 mg/kg），average recoveries for total haloxyfop ranged from 80.7% to 114%，with relative standard deviations（RSD） of 1.4%－11%．The limit of quantitation was as low as 0.01 mg/kg．The method showed a fully converted step from haloxyfop-esters to haloxyfop，and it was suitable for the analysis of total haloxyfop residues in plant-derived foods．关键词：total haloxyfop;alkaline hydrolysis;dispersive solid phase extraction;plant-derived foods;liquid chromatography－tandem mass spectrometry
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发布时间：2023-02-13 - 摘要：VX（O-Ethyl S-（2-diisopropylamino） ethyl methylphosphonothiolate） is one of nerve agents with high toxicity，which could easily penetrate into the skin．Once being poisoned，the normal conduction function of the nervous system might be destroyed in a short time，causing breathing difficulties，severe convulsions，loss of consciousness and other symptoms．The most horrible thing is that only a few milligrams of VX could cause death．In 2017，Kim Jong Nam，the eldest brother of North Korea's top leader，died of this poison，which had attracted a great concern all over the world．Studies have shown that zirconium hydroxide could effectively hydrolyze VX through basic t-OH and acidic b-OH．In this study，an analytical method was established for the determination of the degradation rate of zirconium hydroxide powder on VX by gas chromatography with flame photometric detector coupled with aqueous phase termination－solvent extraction．Qualitative analysis and quantitative analysis were depended on retention time and internal standard method respectively．The pretreatment method for liquid－solid decontamination samples was optimized．The effects of extractants，including n-hexane and dichloromethane，extraction methods，such as ultrasound and oscillation，terminators，and standing time on the recovery of VX were investigated．Gas chromatography was used to detect the internal standard and VX，with the retention times of 11.603 min and 12.080 min，respectively．Generally，terminators are used in the degradation process to achieve the purpose of eliminating the activity of decontaminants．However，the most critical thing in this system is to select a terminator that could make the unreacted VX desorb from the adsorption sites of Zr（OH）4．Acidic substances may react with VX to form salt，increasing its solubility in water and making it difficult to extract it into the organic phase. Strong alkaline substances have a degradation reaction with VX．As a result，weak alkaline substances are suitable for termination．It was found that the borax buffer solution has a stable pH value and the best termination effect．Experimental results showed that the sample，which was terminated with 10 mL of 0.05 mol/L borax aqueous solution，extracted with 50 mL of dichloromethane，shaking for 20 s and standing for 10 min，had the best extraction rate．The recovery reached to 87.8%－90.3%，with the relative standard deviation（RSD） not more than 1.2%．Within the range of 9.7－388.0 μg/mL，there existed a good linear relationship for VX degradation rate with a correlation coefficient of 0.996 9．The detection limit（LOD） and the quantitation limit（LOQ） of this method were 0.05 μg/mL and 0.15 μg/mL，respectively．Using the optimized method，the degradation rate for VX variation time was investigated，which conformed to the pseudo－first－order kinetic process，and the reaction rate constant（k） was 0.019 2 min－1．With a simple，rapid and safe pretreatment，high sensitivity and accuracy，the method provides a reference for evaluation of the decontamination reaction of amphoteric hydroxide substances．关键词：zirconium hydroxide;VX;degradation rate;gas chromatography
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发布时间：2023-02-13
Experimental Techniques and Methods
- 摘要：Rolling circle amplification（RCA） is a simple and isothermal DNA amplification technique that is used to generate thousands of repeating DNA sequences using circular templates under the catalysis of DNA polymerase．Compared to alternating temperature nucleic acid amplification such as polymerase chain reaction（PCR） amplification，RCA is more suitable for on-spot detection with no need of the expensive thermal circulation meter．In this paper，the principle and classification of RCA are introduced，and the applications of RCA in the detections of bacteria，viruses and other pathogenic microorganisms are reviewed．Finally，the perspectives of RCA in the detection of pathogenic microorganisms are anticipated．The RCA method has great potentials in the detection of pathogenic microorganisms．Furthermore，it also could be used in the detection of severe acute respiratory syndrome coronavirus 2．关键词：rolling circle amplification;padlock probe;pathogenic microorganism;detection
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发布时间：2023-02-13
Review
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