最新刊期
卷 40 ， 期 9 ， 2021
- 摘要：Peanut is an important oil and economic crop in China， which has been well accepted by consumers as it could be eaten fresh， used to extract oil， and also be processed into peanut products. In recent years， as a result of abuse of pesticide， the quality and safety risks of peanuts have become an increasingly important issue. Gas chromatography－tandem mass spectrometry（GC－MS/MS） combined with automatic QuEChERS pre-treatment equipment is an effective method for the detection of multi-pesticide residues. Thus， a rapid method based on GC－MS/MS was established for the simultaneous determination of 297 pesticides in peanut. The pretreatment parameters was optimized by comparing the spiked recoveries obtained from different extract solvents（acetonitrile， acetonitrile containing 1% acetic acid and acetonitrile containing 2% acetic acid）， different volumes of extract solvents（10， 15 and 20 mL）， different buffer salts（anhydrous magnesium sulfate， sodium acetate） and different purification combinations（primary secondary amine（PSA） + octadecylsilane（C18）， PSA + C18-bonded zirconium rubber（Z－Sep+）， PSA + C18 + Z－Sep+， EMR－lipid）. Under the optimized conditions， 2 g samples were soaked with 2 mL ultrapure water， the pesticides in the peanuts were extracted using acetonitrile containing 1% acetic acid， salted out using 4 g anhydrous magnesium sulfate and 1 g sodium acetate. Then the solution was purified using 100 mg PSA + 200 mg C18 + 100 mg Z－Sep + automatic QuEChERS pre-treatment device combined with centrifuge device by vortex vibration through a purification tube which included an inner tube， an outer tube and a filtration membrane. Pesticides were separated on an HP－5MS UI capillary column using temperature programming， determined by GC－MS/MS in positive ion multiple mode and quantified by external standard method. The matrix effects were evaluated with the established method. Results showed that 25.25% of the pesticides exhibited enhancing matrix effects， while 2.02% of them exhibited inhibition matrix effects and 72.73% of them exhibited weak matrix effects. Matrix-matched standard curve was used to reduce the matrix effects on detection of the pesticide residues. Methodological verifications were evaluated for the established method， and the results showed that there were good linear relationships for all the pesticides in the corresponding range， with their correlation coefficients（r2） greater than 0.995. The limits of quantitation（LOQs） were 2－10 μg/kg. The recoveries for 297 pesticides at four spiked levels of 10， 20， 50 and 100 μg/kg were in the range of 72.7%－116%， 71.9%－117%， 73.2%－112% and 71.5%－120%， with relative standard deviations（RSDs） of 0.90%－15%， 0.70%－15%， 0.60%－14% and 0.40%－15%， respectively. The proposed method was applied to the detection of 8 batches of peanut samples purchased from local supermarket. The results demonstrated that 6 batches of the peanut samples were found containing pesticide residues， in which 17 pesticides were detected in total. The concentration of dicrotophos was the highest among all pesticides， reaching 34.67 μg/kg. Therefore， the developed method was simple， rapid， sensitive and automatic， and was suitable for the rapid detection of pesticide residues in peanuts.关键词：peanut;multiresidue analysis;automatic QuEChERS;gas chromatography－tandem mass spectrometry（GC－MS/MS）
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发布时间：2023-02-13 - 摘要：A novel， simple and rapid method was established for the determination of estradiol（E2）， estradiol（E3） and estrone（E1） in water， based on solid-phase micro-extraction（SPME） using porous metal－organic framework MIL－101（Cr） filled syringe nylon filter combined with high performance liquid chromatography－fluorescence detector. Firstly， the MIL－101（Cr） powder material was prepared by the hydrothermal synthesis method， whose structure， crystal forms and surface properties were proved by characterization of X－ray diffraction（XRD）， scanning electron microscopy（SEM）， nitrogen adsorption－desorption isotherms and pore size distribution. Secondly， the integrity of the nylon membrane in the proposed SPME device was verified by simulating the solid-phase extraction process. Next， the dominant parameters affecting enrichment efficiency， including extraction speed， sample pH value， salt concentration， washing and desorption conditions were investigated. It was found that when the sample was set at pH 6.0， the salt concentration was 0， the syringe speed was 2.5 mL/min， the elution solvent was methanol， and the washing solvent was 2 mL of 10% methanol/H2O， the extraction effect for the three targets was the best. Under the optimized conditions， three target estrogens in 10 mL water sample could be adsorbed within 4 min and eluted within 1 min. This method showed good linear relationships in the range of 0.2－500 μg/L for E2 and E3， and 5－500 μg/L for E1， with their correlation coefficients（r2） of 0.998 2－0.999 3. The limits of detection for three analytes were 0.05， 0.06 and 1.50 μg/L， respectively. The relative standard deviations（RSD） for intra-day（n = 6） and inter-day（n = 3） were in the ranges of 0.20%－3.2% and 5.9%－6.1%， respectively．The recoveries for all targets in water samples at three spiked levels ranged from 84.1% to 108%， with RSDs not more than 5.5%. The developed method is simple and sensitive， and could be used for the rapid determination and accurate quantification of estrogens in water samples. In this method， MIL－101（Cr） and nylon membrane showed a synergistic adsorption effect on estrogen， providing a new strategy for multi-objective purification and extraction from complex environmental samples.关键词：solid-phase micro-extraction（SPME）;high performance liquid chromatography（HPLC）;metal－organic framework;MIL－101（Cr）;estrogen;nylon filter
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发布时间：2023-02-13 - 摘要：A rapid and accurate analysis method based on rapid solid phase extraction and ultra performance liquid chromatography－tandem mass spectrometry（UPLC－MS/MS） was developed for the determination of 25 kinds of sulfonylurea herbicides and triazolopyrimidine sulfonamides herbicides in aquatic products. Firstly， the pretreatment conditions for the 25 pesticides in aquatic product samples were systematically optimized， based on recoveries， purification efficiencies and other factors， acetonitrile was used as the extraction solvent， and a SHIMSEN QVet－NM + rapid solid phase extraction cartridge was selected as the pretreatment purification column. Then， the chromatographic conditions and MS parameters were optimized. Finally， the chromatographic separation was performed on a Shim－pack GIST C18（2.1 mm × 50 mm × 2.0 μm） column under linear gradient elution using 0.1% formic acid solution and acetonitrile as the mobile phases. The 25 kinds of sulfonylurea herbicides and triazolopyrimidine sulfonamides herbicides were detected by triple quadrupole MS with electrospray ionization（ESI） in multiple reaction monitoring（MRM） mode under both positive and negative conditions， and quantified by a matrix-matched external standard method. The 25 herbicides showed good linear relationships in the concentration range of 0.20－50 μg/L with correlation coefficients（r2） greater than 0.994. The limits of detection（LOD） and limits of quantitation（LOQ） were in the ranges of 0.30－1.3 μg/kg and 1.2－5.0 μg/kg， respectively. The average recoveries for the analytes at three spiked levels varied from 62.7% to 122%， with the relative standard deviations（RSD） of 0.72%－18%. Results of the matrix effects（ME） for 25 herbicides showed that all of the herbicides exhibited matrix inhibition effects in grass carp， penaeus vannamei and meretrix meretrix. The matrix effects could be reduced by the matrix-matched standard curve method. The method was applied to the detection of 25 herbicides in aquatic product samples. None of them were found in the samples. The experimental results indicated that the proposed method was simple， quick， accurate and sensitive， and was suitable for the determination of 25 kinds of sulfonylurea herbicides and triazolopyrimidine sulfonamides herbicides in aquatic products.关键词：sulfonylurea herbicides;triazolopyrimidine sulfonamides herbicides;aquatic products;ultra performance liquid chromatography－tandem mass spectrometry;rapid solid phase extraction
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发布时间：2023-02-13 - 摘要：In this study， a simple but effective fluorescent probe（CQ） was constructed for the detection of sulfite. The N-methylquinoline trifluoromethanesulfonate fragment as the sulfite response site was linked to the 4-cyanobenzoacetonitrile fragment using a C
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发布时间：2023-02-13 - 摘要：A gas chromatography－tandem spectrometric（GC－MS/MS）method was developed for the rapid determination of 232 pesticide residues in six kinds of dairy products. The samples were extracted with acetonitrile containing 1% acetic acid， then separated by liquid－liquid extraction with anhydrous sodium acetate and anhydrous magnesium sulfate， and followed by dispersive solid phase purification using anhydrous magnesium sulfate， C18 and PSA. The supernatant was concentrated under nitrogen， redissolved， then analyzed by GC－MS/MS under multiple reaction mode（T－MRM）， and finally quantified by matrix matched internal standard method. Results showed that there existed good linear relationships for 232 pesticides with correlation coefficients more than 0.99. The limits of quantitation（LOQ）were in the range of 0.000 4－0.05 mg/kg. The spiked recoveries at three levels of 0.01， 0.02 and 0.10 mg/kg in milk were in the range of 65.2%－110%， with relative standard deviations（RSDs） of 3.6%－13%. This method is sensitive， reliable and accurate， and could be applied to the determination of 232 kinds of pesticide residues in dairy products， as well as the multi-pesticide residues in the routine analysis.关键词：QuEChERS;GC－MS/MS;pesticide residues;dairy products
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发布时间：2023-02-13 - 摘要：Postmortem Interval（PMI） estimation is important in investigation of crime. However， the PMI is susceptible to various endogenous and exogenous factors. The objective of this work is to investigate the influence of gender on the postmortem changes of metabolites in liver tissue by gas chromatography－mass spectrometry（GC－MS）. Seventy-two Sprague－Dawley（SD） rats（half males and half females） were mechanically asphyxiated and stored under the conditions of controlled humidity and temperature. The cadaveric phenomena were observed and recorded according to PMI（0， 6， 12， 24， 48， 72 h）. The right liver lobes were collected by dissection at the predesignated PMIs. The whole metabolome was analyzed by GC－MS after the sample was preprocessed. After data preprocessing， multivariate statistical analyses were performed by principal component analysis（PCA） and partial least squares（PLS）. The variable Importance in the Projection（VIP） and Kruskal－Wallis（K－W） test were used to select the common differential metabolites related to the PMI of both genders. The gender differences of PMI related metabolites were analyzed. The liver samples of both genders at different times after death could be completely distinguished by PCA and PLS， respectively. The results of 7-fold cross validation and 200 times replacement validation of PLS model showed that the model fitted well. Forty-two metabolites in male rat liver were selected based on VIP values and K－W test， and 41 metabolites were selected in female rat liver. Thirty-one common differential metabolites（59.6%） were both related to PMI， including amino acids， fatty acids， biogenic amines and other endogenous metabolites or postmortem catabolites. Eighteen of them showed gender differences. There were two types of metabolites with gender differences in lives： metabolites with gender difference at 0 h and other time points， and metabolites with gender difference after 24 h. This work shows that gender has an effect on the changes of metabolites in different tissues， and gender should not be ignored when metabolites are used for PMI estimation.关键词：postmortem interval;metabolomics;gas chromatography－mass spectrometry;liver;gender
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发布时间：2023-02-13 - 摘要：The effects of different chromatographic columns， modifiers， additives， flow rates， column temperatures and back pressures in supercritical fluid chromatography（SFC） on the separation of 9 flavonoids， e.g. formononetin， isorhamnetin， calycosin， kaempferol， quercetin， astragalin， ononin， isoquercitrin and calycosin-7-glucoside were investigated. Meanwhile， a SFC method was established for the determination of 5 flavonoids in Astragalus membranaceus， which was compared with high performance liquid chromatography（HPLC）. The separation was performed on an Agilent ZORBAX RX－SIL column（4.6 mm × 150 mm， 5 μm） by gradient elution， with CO2－0.1% phosphate acid methanol solution as mobile phase at a flow rate of 3 mL/min， a column temperature of 35 ℃ and a back pressure of 10 MPa. Results indicated that the nine flavonoids could be separated within 10 min. The five quantified flavonoids all had good linear relationships（r2 ≥ 0.963 2） in the certain concentration ranges. The detection limits ranged from 10.69 μg/mL to 16.21 μg/mL. The intra-day and inter-day relative standard deviations（RSD）were in the range of 1.3%－2.0% and 1.6%－2.2%， respectively. The five flavonoids had good stability within 48 h， with RSDs of 1.6%－3.8%. The repeatabilities of five flavonoids ranged from 3.6% to 6.0%. The average recoveries were in the range of 91.8%－112%. Compared with the HPLC method， the SFC method was more rapid， economical and environmental friendly as the retention time sequences of the components in the two methods were almost opposite. Its retention and selectivity were greatly affected by columns， modifiers and additives， and additives had obvious effects on chromatographic peak shape.关键词：supercritical fluid chromatography（SFC）;high performance liquid chromatography;Astragalus membranaceus;flavonoids;rapid analysis
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发布时间：2023-02-13 - 摘要：Based on QuEChERS and cold induced liquid－liquid extraction（CI－LLE） technique， an analytical method for the determination of 77 pesticide residues in vegetables and fruits was developed by ultra-high performance liquid chromatography－high resolution mass spectrometry. The samples were extracted， salted out， and cleaned up by traditional QuEChERS method， and further enriched and cleaned up by CI－LLE technique using 40% acetonitrile－water solution. The chromatographic separation of pesticides was performed on a C18 column（2.1 mm × 150 mm， 2.6 μm） using water－methanol （containing 0.1% formic acid and 4 mmol/L ammonium formate for each） as mobile phases by gradient elution. The pesticides were analyzed by the high resolution mass spectrometry in full scan mode by time sediment， and quantified by internal standard method. Results showed that 77 pesticides had good linearity in the certain concentration ranges with relative coefficients（r2） larger than 0.99. The limits of detection and limits of quantitation were in the ranges of 0.02－0.20 μg/kg and 0.05－0.50 μg/kg， respectively. At four different spiked levels， the recoveries for pesticides in vegetables and fruits ranged from 70.8% to 119%， with relative standard deviations（RSDs） of 0.70%－15%. The method is simple and reproducible， and could be used to reduce matrix effect on the detection of pesticide residues with high sensitivity， accuracy， and precision. Therefore， it could meet the requirements for multi-residue detection of pesticides， and be applied to the qualitative and quantitative determination of pesticides in real samples.关键词：pesticide residues;cold induced liquid－liquid extraction;high resolution mass spectrometry;vegetables;fruits;QuEChERS
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发布时间：2023-02-13 - 摘要：Bisphenol compounds are a type of environmental estrogens， which are mainly used in the synthesis of polycarbonate plastics， epoxy resins， polyester resins， etc. This type of estrogens often appear in different water environments such as tap water， rivers and lakes due to the incomplete polymerization in production process or the polymer degradation in use. Bisphenol compounds could cause great harm to human health and the survival of other organisms. Therefore， detection of bisphenol compounds in water is particularly important. In this study， a high performance liquid chromatography with pipette tip solid-phase extraction（PT－SPE） using carboxylated multi-walled carbon nanotubes as adsorbent was developed for the determination of 5 bisphenol compounds， i.e bisphenol A（BPA）， bisphenol E（BPE）， bisphenol F（BPF）， bisphenol Z（BPZ） and tetramethyl bisphenol A（TMBPA） in drinking water. The water samples with different pH were adjusted by formic acid and ammonia solutions， then loaded into the PT－SPE cartridge. A Shim－pack GIST C18（250 mm × 4.6 mm， 5 μm） chromatographic column and an ultraviolet detector（UV） were used for the determination of bisphenol compounds. Effects of type and amount of the carbon nanotubes， pH value of the sample solution， and type and amount of the eluent on recovery of the method were systematically investigated in this paper. The experimental results showed that the enrichment effect of carboxylated multi-carbon nanotubes was significantly better than those of aminated multi-walled carbon nanotubes and hydroxylated multi-walled carbon nanotubes. With the increase of dosage of carboxyl multi-walled carbon nanotubes from 0.5 mg to 2.0 mg， the recoveries for five bisphenol compounds increased firstly and then decreased. When the dosage reached 1.5 mg， the highest recoveries were obtained. The pH values of water samples were also one of the important factors affecting the adsorption of bisphenol compounds by multi-walled carbon nanotubes. When the pH values varied from 3 to 5， the recoveries increased slightly， and the highest recovery was obtained at pH 5. As the pH values continued to increase（pH 5－7）， the recoveries showed a downward trend. The type and amount of eluent could also affect the recoveries and enrichment of bisphenol compounds in solid-phase extraction. After systematical optimization， 0.5 mL methanol was finally selected as the eluent. Under the optimal experimental conditions， good linear relationships for 5 bisphenol compounds were obtained in the range of 2.2－220 µg/L with correlation coefficients（r） not less than 0.998 5. Method detection limits（MDL） of the developed method were in the range of 0.005－0.097 μg/L. The recoveries for the bisphenol compounds at three spiked levels of 22， 110， 220 μg/L ranged from 91.1% to 110%， with relative standard deviations（RSD） not more than 4.3%. Compared with previous reported methods， this method exhibited several advantages such as simple pretreatment， good selectivity and low detection limit， which could be used for the determination of bisphenol compounds in drinking water.关键词：carboxylated multi-walled carbon nanotubes;bisphenol compounds;high performance liquid chromatography;drinking water;solid-phase extraction
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发布时间：2023-02-13 - 摘要：A novel molecularly imprinted electrochemical sensor sensitized with aluminium oxide （Al2O3） and hydroxylated multi-walled carbon nanotubes（MWCNTs） was prepared for the sensitive determination of chloramphenicol（CAP） by using CAP as template molecule， m-aminophenol（MAP） and β-cyclodextrin（β－CD） as binary functional monomers. The surface morphology and electrochemical performance of the imprinted sensor were characterized by scanning electron microscopy（SEM）， differential pulse voltammetry（DPV） and electrochemical impedance spectroscopy（EIS）. The experimental parameters influencing the response of the imprinted sensor， such as modification amount of MWCNTs and Al2O3， molar ratio of template molecule to functional monomer， number of electropolymerization cycles， eluent type， elution time， pH value and incubation time were also optimized. Results showed that the prepared sensor exhibited high selectivity and sensitivity in the detection of CAP， which was attributed to the synergistic effect of Al2O3 and MWCNTs to significantly enhance the surface area and catalytic performance of the modified electrode， as well as high affinity and selectivity of imprinted membrane prepared with the binary functional monomers. Under the optimal conditions， the peak current was linearly related to the CAP concentration in the range of 1.0－60.0 nmol/L， with a detection limit（3S/k） of 0.14 nmol/L. The sensor was applied to detect CAP in tap water， chicken feedstuff and milk samples， with recoveries of 88.0%－110% and relative standard deviations less than 10%. The proposed method is simple， accurate and reliable.关键词：chloramphenicol;molecular imprinting;electrochemical detection;bifunctional monomer;hydroxylated multi-walled carbon nanotubes;aluminium oxide
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发布时间：2023-02-13 - 摘要：Coumarins are widely used in anti-tumor，anti-oxidation，anti-inflammatory and other pharmacological researches due to their good fluorescence spectrum characteristics. It was showed in the previous study that 3-benzimidazole-7-hydroxycoumarin could serve as a fluorescent probe to monitor intracellular pH changes（pKa = 7.20， pH 6.50－8.30）. Herein， 3-（6-methoxy-1H-benzimidazole）-7-hydroxy coumarin（BC） was synthesized by introducing a methoxy electron donor group onto the C－3 benzimidazole of 3-methoxy-1H-benzimidazole. The structure of the probe compound was determined by hydrogen nuclear magnetic resonance spectroscopy（1H NMR）， carbon nuclear magnetic resonance spectroscopy（13C NMR）and high resolution mass spectrometry（HR－MS）. The fluorescence properties and pH value of the probe on the detection were investigated. Results showed that the probe has high selectivity and anti-interference ability. The fluorescence intensity of the probe increases with the increase of pH value in the range of pH 5.5－10.0（pKa = 8.36）. Furthermore， BC could be successfully applied to mark pH changes in HeLa cells， showing a good prospect of biomedical applications.关键词：pH;fluorescent probe;7-hydroxycoumarin;cell imaging
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发布时间：2023-02-13 - 摘要：A new method based on solid phase extraction/ultra performance liquid chromatography－triple quadrupole mass spectrometry was developed for the determination of ten ginsenosides in roots， leaves and flowers buds of panax ginseng. Firstly， the fragmentation process of the target compounds was determined by analyzing the fragments produced from the ionized lysis of ginsenosides under the negative ion mode of electrospray ion source（ESI－）. Then， the conditions of mass spectrometry and chromatography for the effective separation of 10 ginsenosides were optimized. Meanwhile， an Alumina－N/XAD-2 SPE cartridge composite solid phase extraction column was chosed as the pre-treatment purification column in this study， and XAD－2 macroporous adsorption resin and neutral alumina were also selected as the purification column materials. The principle of this research was based on the molecular exclusion effect of XAD－2 macroporous adsorption resin， which was liable to elute carbohydrates， proteins and organic acids in the sample， while the pigments and flavonoids in the sample were adsorbed by the neutral alumina. Therefore， the ginsenosides were able to further enriched and purified. Finally， the ginsenosides were separated on a Hypersil Gold C18 chromatographic column（100 mm × 2.1 mm， 1.9 μm） using 5 mmol/L ammonium acetate solution containing 0.1% formic acid and acetonitrile as the mobile phases. Furthermore， the ginsenosides were detected with electrospray ionization in negative ion mode under multiple reaction monitoring（MRM） mode. Results showed that there were good linear relationships for ten ginsenosides in the concentration range of 5－2 500 ng/mL， with their correlation coefficients（r） not less than 0.998 0. The limits of detection and limits of quantitation were in the ranges of 0.25－2.5 mg/kg and 0.75－7.5 mg/kg， respectively. For a typical sample of ginseng leaves， the average recoveries at different spiked levels ranged from 87.3% to 110%， with relative standard deviations（RSD） of 1.4%－9.3%. However， the results of different batches of ginseng， ginseng leaves and ginseng flowers showed that the ginsenoside components in leaves and flowers were similar to those in root， while the total contents of some ginsenoside monomers and ten main ginsenosides were more than those in the ginseng root. Overall， the results demonstrated that the proposed method was sensitive and accurate， and was suitable for the ginsenosides quantification in ginseng plants. The method could be applied to the content determination and quality control of ginseng， ginseng flowers and ginseng leaves， and provides a certain basis for the rational development and utilization of ginseng resources.关键词：ginsenosides;ultra performance liquid chromatography－triple quadrupole mass spectrometry;solid phase extraction;ginseng leaves;ginseng flowers
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发布时间：2023-02-13 - 摘要：Determination of nicotine metabolites in human urine provides an ideal tool for the assessment of the tobacco use-related nicotine exposure， provided that the considered metabolites comprise a large share of the amount exposed. Nicotine and its nine metabolites mentioned in this research comprised of more than 90% of the total nicotine metabolites. A hydrophilic interaction high performance liquid chromatography－tandem mass spectrometry was developed for the simultaneous determination of nicotine and its nine metabolites in human urine. The urine sample was diluted 20 times with a mixed solvent of acetonitrile and methanol（3∶1， by volume）， and subsequently filtered through a 0.22 μm membrane for direct analysis. Then these metabolites were separated on an Atlantis HILIC Silica column（3.0 mm × 100 mm， 3.0 μm） by gradient elution， with 10 mmol/L ammonium formate aqueous solution（adjusted to pH 3.0 with formic acid）－acetonitrile as mobile phases， then detected by tandem mass spectrometry with electrospray ionization in positive ion mode under multiple reaction monitoring（MRM）， and finally quantified by isotope-labelled internal standards. Results showed that the calibration curves for nicotine and its nine metabolites were linear in the certain concentration range with correlation coefficients（r） larger than 0.997. The limits of detection（LOD） and quantitation（LOQ） were in the ranges of 0.03－0.24 ng/mL and 0.10－0.80 ng/mL， respectively. The recoveries at low， medium and high spiked levels in real samples ranged from 81.9% to 110%， with intra-day and inter-day relative standard deviations of 0.50%－6.7%. The developed method could meet the requirements for high-throughput detection of nicotine and its nine metabolites in human urine with simplicity， high sensitivity and stability.关键词：nicotine;metabolites;urine;hydrophilic interaction chromatography;tandem mass spectrometry
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发布时间：2023-02-13
Scientific Papers
- 摘要：Protein is an essential component of organisms. Damages and diseases of the body could be known from analysis of proper proteins， and thus analysis of proteins by capillary electrophoresis（CE） is important in the field of clinical medicine. However， the current researches on pulsed field capillary electrophoresis（PFCE） mainly focus on the improvement of separation performance of DNA， and there is little research about protein analysis by PFCE. To improve the separation performance of proteins， lysozyme， growth hormone， carbonic anhydrase， actin， bovine serum albumin and phosphorylase B were taken as the samples， using hydroxyethyl cellulose（HEC） as the sieving polymer， applying the capillary with 6 cm of effective length and 8 cm of total length， performing the PFCE of proteins， and investigating the effect of pulse frequencies and modulation depth on the separation performance of proteins sized range of 14.4－97.4 kDa for the first time. Results demonstrated that， compared with the direct current CE（DCCE） under 100 V/cm of electric field strength， the PFCE employing 1.4% HEC as the sieving polymer， a 100 V/cm of average electric field strength， a 10 Hz of pulsed frequency and a 250% of modulation depth would make the migration time of proteins with same molecular weight decrease about 6.6%－9.6%. The resonant frequency for the protein and pulsed electric field was 10 Hz. The migration time of protein molecule was increased with the growth of pulsed frequency when the pulsed frequency was lower than the resonant frequency. In contrast， the migration time was decreased if the pulsed frequency was higher than the resonant frequency. The resolution could be increased about 34.1%－88.1%， and the maximum theoretical plate number reached to 4.03 × 104 if the frequency of the pulsed electric field was the same as the resonant frequency. Under the same average electric field strength， the migration time of protein decreased with the growth of modulation depth from 0 to 250%， and the Joule heating in the sieving polymer induced by pulsed electric field increased 2.64 times than that under direct current electric field. The growth of Joule heating will make the viscosity of the polymer reducing. Consequently， the decrease of the migration time was more obvious if the molecular weight of protein was larger. The migration time of phosphorylase B was reduced about 9.6% when the modulation depth was raised from 0 to 250%. The resolution between the adjacent protein molecules was not obviously deteriorated， even though the migration time was shorter. This work provides a new method for improving the separation performance of protein.关键词：capillary electrophoresis（CE）;pulsed electric field;protein;separation
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发布时间：2023-02-13 - 摘要：In this work， CsPbBr3 quantum dots（QDs） were used as a new kind of fluorescence（FL）probe to detect cholesterol（CHO）. By using 3-aminopropyltrimethoxysilane（APTES） as the functional monomer and CHO as the template molecule， a CHO molecularly imprinted layer was formed on CsPbBr3 QDs via a simple silica sol－gel process. The formed silica layer not only improve the stability of CsPbBr3 QDs by protecting CsPbBr3 QDs from direct exposure to air and humidity， but also renders CsPbBr3 QDs good selectivity to CHO. During the detection process， CHO was captured into the specific cavity sites of CHO-imprinted SiO2 shell layers on CsPbBr3@SiO2 QDs to cause the decrease of the FL intensity of CsPbBr3 QDs. Under the optimal conditions， a good linear relationship was obtained between fluorescence quenching efficiency and the logarithm of CHO concentrations in the range of 1.00 × 10－11－5.00 × 10－8 mol·L－1， with a detection limit down to 2.48 × 10－12 mol·L－1. This sensor showed better sensitivity and selectivity to CHO than to other interferences. This work broadens the application horizon of CsPbBr3 QDs and provides a new strategy for CHO detection.关键词：sol－gel;perovskite quantum dots;cholesterol;fluorescence sensor
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发布时间：2023-02-13 - 摘要：Based on near-infrared spectroscopy and chemometrics， a rapid and non-destructive identification method for different varieties and adulterate notoginseng was proposed. Meanwhile， samples of Sedum notoginseng， Chrysanthemum notoginseng， Xue notoginseng and Tian notoginseng were collected， and the near-infrared spectra for complete， powder and adulterated samples were obtained. Single and combined pretreatment methods were used to eliminate the interferences in the spectra， in which the best pretreatment method was screened out. Combined with the principal component analysis method， the identification models for different varieties and adulterated samples were established. Results showed that with the original spectra of powder and adulterated samples，100% identification accuracy could be obtained. Affected by the physical properties，the identification accuracy for the complete samples was 9.38%，but the value could reach 93.75% with the help of continuous wavelet transform. The combined pretreatment method could be used to eliminate the various interferences in the spectra， and the optimization pretreatment method could significantly improve the identification. With the help of De-bias + first derivative， De-bias + continuous wavelet transform， and second derivative + standard normal variable transformation， the identification accuracy of complete samples reached 93.75%. The above results showed that the rapid and non-destructive identification of different varieties and adulterate notoginseng could be realized by near-infrared spectroscopy technique combined with chemometrics.关键词：near-infrared spectroscopy;notoginseng;adulterate;non-destructive identification;principal component analysis
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发布时间：2023-02-13 - 摘要：A novel analytical method for simultaneous determination of xylazine and its metabolite 2，6-dimethylaniline（DMA） in pork was developed based on QuEChERS/liquid chromatography－tandem mass spectrometry（LC－MS/MS）. The analytical process was as follows： pork meat samples were homogenated for 1 min， followed by extraction with acetonitrile－2% acetic acid， cleanup with C18/PSA mixed adsorbent. The extracts were evaporated to dryness with high-purity nitrogen gas， and then dissolved in mobile phase A for LC－MS/MS analysis in positive ionization mode using multiple reaction monitoring（MRM）. The separation was carried out on a Waters C18 separation column（100 mm × 2.1 mm， 3.5 μm） using 0.1% formic acid－water and 0.1% formic acid－acetonitrile as mobile phases. The effects of extraction solvents， types and amounts of adsorbents on the recoveries were investigated. Results showed that the effects of blank matrix on MS response of xylazine and DMA were checked， and the results showed weak suppression effects for xylazine（0.86） and DMA（0.89）. The quantitations of xylazine and DMA were completed by a matrix-matched external calibration method. The limits of detection for xylazine and DMA were 0.10 μg/kg and 0.30 μg/kg， and the limits of quantitation were 0.32 μg/kg and 1.00 μg/kg， respectively.Recoveries for xylazine and DMA were in the ranges of 95.6%－108% and 70.3%－79.5%， with their relative standard deviations（RSD） of 2.6%－2.8% and 3.1%－5.0%， respectively. To validate the developed method， ten pork samples collected from local supermarkets were determined. Xylazine was not detected in the ten samples except for one sample where 1.13 μg/kg of DMA was found. The present method is simple， rapid， sensitive and efficient， and is suitable for the detection of xylazine and DMA residues in pork.关键词：xylazine;2， 6-dimethylaniline;QuEChERS;liquid chromatography－tandem mass spectrometry;pork
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发布时间：2023-02-13 - 摘要：Lactose and lactulose in liquid milk are isomers with similar retention properties， which makes separation and detection on lactulose by chromatography difficult. At present， although a variety of liquid chromatography detection methods have been reported， there are some problems in the simplicity of the pretreatment， the applicability of the chromatographic column and the stability of the separation effect. A method for the determination of lactulose in liquid milk by high performance liquid chromatography with evaporative light scattering detection（HPLC－ELSD）was developed. The protein was deposited with 0.4 mol/L ammonium acetate（pH 3.8）. The sugar analysis column was used for separation， and the evaporative light scattering detector was applied to detection. There was a good linear relationship for lactulose in liquid milk in the range of 1.0－100 mg/L， with a correlation coefficient（r2） of 0.998 0. The detection limit and the quantitative limit were 15 mg/L and 50 mg/L， respectively. The recoveries were in the range of 85.1%－110%， with relative standard deviations（RSDs） not more than 7.5%. The method is simple to operate， and could be completed within 8 min. It could meet the requirements for daily detection of lactulose with good repeatability and high accuracy.关键词：lactulose;high performance liquid chromatography;evaporative light scattering;liquid milk
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发布时间：2023-02-13
Experimental Techniques and Methods
- 摘要：To monitor florfenicol residues in animal-derived foods and feeds， a monoclonal antibody with excellent specificity and sensitivity was prepared by using the antigen reported previously to immunize BALB/c mice and hybridoma technique. An indirect competitive enzyme-linked immunosorbent assay was established based on this antibody. The optimal conditions were finalized as follows： a coating antigen concentration of 0.05 μg/mL， an antibody concentration of 0.1 μg/mL， a competition reaction time of 30 min， a PBST diluent for analyte， primary antibody and secondary antibody with a Tween－20 of 0.05%， a secondary antibody concentration of 0.167 μg/mL and its reaction time of 30 min. Under the optimal conditions， the icELISA method for detection of florfenicol was established with an IC50 of 9.48 ng/mL， a linear range of 1.75－51.36 ng/mL and a limit of detection（LOD）of 0.64 ng/mL. There was no obvious cross-reactivity between the icELISA and its structural and functional analogs such as chloramphenicol， thiamphenicol， etc. The spiked recoveries for florfenicol in samples ranged from 88.1% to 107% with relative standard deviations（RSDs）less than 15%. The developed icELISA method was used to detect fifteen blind samples， of which four blind samples were found to contain florfenicol in different concentrations levels. These results were in good agreement with those of HPLC－MS/MS. Therefore， the developed icELISA exhibited a potential practicality in detection of florfenicol in animal meat and feed samples.关键词：florfenicol;animal meat and feed;monoclonal antibody;immunoassay
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发布时间：2023-02-13
Experimental Techniques and Method
- 摘要：Sediments and particulate matters in aquatic environment take the roles of main carriers and final destinations of hydrophobic and lipophilic organic contaminants， which have been proved to be potential secondary pollution sources for releasing contaminants to aquatic environment again. Organic pollution in sediments and particulate matters is an important factor affecting the safety of aquatic environment. Therefore， it is essential to expand the screening scope of organic contaminants as wide as possible to understand and grasp the comprehensive pollution situation. Liquid chromatography－high resolution mass spectrometry（LC－HRMS） is suitable for the analysis of a wide range of organic pollutants from medium to strong polarity. Its application could not only realize the high-throughput analysis， but also expand the identification of unknowns. The researches on organic contaminants in sediments and particulate matters by LC－HRMS are reviewed in this paper， including the analysis strategies， the analysis process and the practical analysis on target， suspect and nontarget organic compounds， and the high-throughput analysis， screening of emerging contaminants， characteristics and applications of different databases， compound identification confidence level， data independence acquisition and prioritization strategies are focused. Meanwhile， the existing problems and prospects of LC－HRMS applications are summarized and addressed， so as to improve the identification efficiency and better carry out the screening and monitoring of organic contaminants in environmental samples. Furthermore， the relevant general content of HRMS involved in this article also provides a certain reference and inspiration for the applications of this technique in other fields.关键词：sediments;particulate matters;organic contaminants;liquid chromatography;high resolution mass spectrometry;screening
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发布时间：2023-02-13
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