最新刊期
卷 43 ， 期 3 ， 2024
- 摘要：To address the problems that the existing analytical methods for evaluating the relationship between traditional decoction and dispensing granule decoction are not intuitive and not comprehensive from multi-dimensional indexes. In this study，an evaluation method based on multi-index（chemical composition，pharmacodynamic effect） dimension reduction discriminant analysis of the equivalence relationship between traditional decoction and dispensing granule decoction was established. In order to verify the validity of the method，the chemical composition data of the dispensing granule decoction and traditional decoction of baked licorice from manufacturers A，B and C，radix paeoniae alba from manufacturers D and E，and amomi fructus from manufacturers F，G and H were used to verify the analysis. The validation results showed that the established discrimination method could quickly and intuitively discriminate the relationship between traditional decoction and dispensing granule decoction. The baked licorice dispensing granule from manufacturers A，B and C could not be determined to be equivalent to their traditional decoction before the equivalence ratio correction. After the equivalence ratio correction，the two confidence ellipses representing the traditional decoction and the dispensing granule decoction were partially intersected or included，indicating that the two could be partially or completely replaced. The radix paeoniae alba dispensing granule from manufacturers D and E，amomi fructus dispensing granule from manufacturers F，G and H could not be determined to be equivalent to their traditional decoction before and after equivalence ratio correction，and the two could not be replaced by each other. The method established in this study can be quickly，intuitively and comprehensively used to evaluate the equivalence between dispensing granule decoction and traditional decoction in a graphical form.关键词：traditional decoction of Chinese medicine;dispensing granule of Chinese medicine decoction;multi-index dimension reduction discriminant analysis;equivalence
- 173
- |
- 34
- |
- 0
发布时间：2024-03-13 - 摘要：In recent years，bacterial nucleic acid detection has become a common laboratory diagnostic method owing to the continuous outbreak of diseases caused by various bacteria. Bacterial nucleic acid extraction is a key step in the classification and identification of bacteria，and also one of the important techniques for medical diagnosis and drug screening. Current bacterial nucleic acid extraction is dominated by chemical lysis methods，which have obvious drawbacks，such as large sample volume and chemical reagent contamination. Therefore，it is significantly important to develop a rapid，simple and chemically contamination-free device. In this study，we designed a microfluidic chip combining indium tin oxide（ITO） electrodes and polydimethylsiloxane（PDMS） to lysed various bacteria and extracted nucleic acids under direct current（DC） electric field. When bacteria exposed to the DC electric field，transmembrane potentials formed inside and outside of the cell membrane，leading to irreversible changes in the permeability and subsequently bacterial breakdown. Based on this principle，the effects of electric field intensity，electrode distance，lysis time，square resistance of ITO electrode and electrode width on nucleic acid extraction were investigated. Real-time fluorescence quantitative PCR，colony culture，and laser confocal microscopy were employed to jointly evaluate the performance of the chip for bacterial lysis and nucleic acid extraction. The results demonstrated that the chip could lysed a variety of bacteria（including Escherichia coli，Staphylococcus aureus，Staphylococcus epidermidis，Bacillus subtilis，Klebsiella pneumoniae，Salmonella typhimurium，and Pseudomonas aeruginosa） under an electric field strength of 3.0 kV/mm within 3 s and released nucleic acids. The extracted nucleic acids can be directly applied to PCR assays without any purification. The results indicate that an appropriate electric field intensity，electrode distance，and lysis time are more conducive to nucleic acid extraction，and the optimal lysis conditions required for nucleic acid extraction differ slightly for different types of bacteria and need to be adjusted according to the properties of the particular bacteria. In contrast to other methods of bacterial lysis by electrolysis，we validated the performance of the device for bacterial lysis and nucleic acid extraction by quantitative PCR experiments，which can be better integrated with subsequent detection processes. The chip was used in conjunction with real-time fluorescent quantitative PCR to detect bacterial DNA in a linear range of 10-18-10-10 mol/L，with a detection limit as low as 4.2×0-18 mol/L. The chip designed in this work is facile to fabricate，low-cost，easily manipulated，and appropriate for point-of-care testing，especially in resource-limited settings. This study provides a simple，fast，chemical-free，and efficient nucleic acid extraction method for pathogen analysis and medical diagnosis of bacterial infections.关键词：microfluidic chip;electric lysis;nucleic acid extraction;DC electric field;multiple bacteria
- 75
- |
- 32
- |
- 0
发布时间：2024-03-13 - 摘要：A method for the extraction and detection of aroma components in e-liquids by liquid-liquid extraction/gas chromatography-mass spectrometry and automatic deconvolution-Kováts retention index has been developed to provide reference for the inspection，identification，and supervision of fruit flavored e-liquids. Based on liquid-liquid extraction method，the type of extraction solvent was selected. After that the aroma composition and differences between fruity and tobacco flavored e-liquids was analyzed based on the aroma characteristics of the aroma components in the liquids to determine the characteristic aroma components of different fruity flavored e-liquids. The results showed that choosing ether as the extraction solvent weakened the interference of glycerol on the recognition of other components. Qualitative analysis of low content and co-eluting components was achieved by using the automatic deconvolution-Kováts retention index data analysis method. Fifteen components were detected in ten kinds of tobacco flavored e-liquids，with soybean and caramel aroma compounds as the main components. Eighty components were detected in twenty-one kinds of fruit flavored e-liquids，with fruity and floral aroma compounds as the main compounds，and the characteristic aroma components of sixteen types of fruit flavored e-liquids were identified. Through random validation experiments，the method can effectively differentiate between fruit flavored e-liquids and tobacco flavored e-liquids，and identify the flavor types of fruit flavored e-liquids. The detection method established in this paper has the advantages of low sample consumption，simple pre-treatment process，and short sample analysis time. It can meet the needs of detecting aroma components in e-liquids. It also provides a reference for the identification and regulation of the detection of fruity e-liquids.关键词：liquid-liquid extraction;gas chromatography-mass spectrometry;automatic deconvolution-Kováts retention index method;e-liquid;characteristic aroma component
- 123
- |
- 30
- |
- 0
发布时间：2024-03-13 - 摘要：A rapid analytical method for the determination of multi-pesticide residues in olive oil by dispersive liquid-liquid microextraction（DLLME） coupled with gas chromatography-quadrupole-time-of-flight mass spectrometry（GC-QTOF MS） was developed based on the concept of green environmental protection. The effects of acetonitrile acidification concentration，water phase volume and extractant type on the determination of pesticide residues were also investigated. First，the ions with better response and no obvious interference were selected for quantification and characterization. The sample was then pretreated by dispersive liquid-liquid microextraction.After extracted with acetonitrile solution containing 2% formic acid，the supernatant and extractant were rapidly injected into the aqueous phase，and the analytes were taken for instrumental analysis. Finally，a matrix standard solution was used for quantification. The results showed that the linear ranges were 0.02-2 μg/mL for 87.8% of the pesticides and 0.1-2 μg/mL for 12.2% of the pesticides. The correlation coefficients（r2） were all greater than 0.99，and the pesticide residues were well related within their respective linear ranges. The limits of detection（LODs） of all the tested pesticides were 0.002-0.020 mg/kg and the limits of quantitation（LOQs） were 0.007-0.067 mg/kg. Among them，the LOQs of 135 pesticides can reach 0.007 mg/kg and 23 pesticides can reach 0.017 mg/kg，which accounted for 88% of the total quantity. At the three spiked levels of 0.02，0.1 and 0.2 mg/kg，the pesticides with recoveries ranging from 70% to 120% accounted for 76.3% of the total pesticides tested. The pesticides with relative standard deviations（RSDs） less than 10% accounted for more than 94.4% of the total. The method was applied to 10 samples of commercially available olive oil，and five pesticides were detected with the content range of 0.005 7-0.042 7 mg/kg. The method is simple，rapid，sensitive，precise and accurate，with low consumption of reagents and green environment，which can meet the needs of pesticide residue detection in olive oil.关键词：dispersive liquid-liquid microextraction（DLLME）;gas chromatography-quadrupole-time-of-flight mass spectrometry（GC-QTOF MS）;olive oil;pesticide residues
- 124
- |
- 23
- |
- 0
发布时间：2024-03-13 - 摘要：Liquid crystal monomers（LCMs） are a group of manmade chemicals used in display devices，while their wide use has caused environmental pollution and health risks. In this study，a simple，sensitive and accurate analytical methodology was established for the determination of LCMs in indoor dust. For the sample pretreatment，dust samples were mixed with stable isotope substituted internal standards（ISs），namely polychlorinated biphenyls（13C-PCBs） and polybrominated biphenyl ethers（13C-PBDEs），and then extracted by dichloromethane（DCM），and the supernatant was subsequently transferred to another tube after centrifugation. With anhydrous sodium sulfate adding into the extracted solution，the solution was further purified by a mixture absorbent of primary secondary amine（PSA） and octadecyl-modified silica（C18）. Finally，37 LCMs were simultaneously tested on a gas chromatography-tandem mass spectrometry performed under dynamic multi-reaction monitoring mode（dMRM），and the internal standards were used for quantification. Instrumental parameters，the use of extraction solvents and absorbents were optimized. Under the best condition，the 37 LCMs exhibited good linearity in the range of 0.1-50 ng/mL，with a method detection limit of 0.02-1.56 ng/g. The average recoveries of the tested substances at two spiking levels was 65.3%-137%，with relative standard deviations（RSDs） of 0.90%-24%. Twenty real indoor dust samples collected in Beijing were tested. The contents of total LCMs in dust ranged from 38.9 to 125 ng/g，and the average contents of the individual LCMs were from 0.044 7 to 25.1 ng/g. Twenty-two LCMs out of the 37 target LCMs presented relatively high detection frequency（higher than 50%），which indicated the ubiquity of LCMs in indoor environment in Beijing. With the spread of smart electronic devices，it is foreseeable that the pollution of LCMs in indoor environment will be rather serious. The analytical method developed in our study presented multiple advantages including simple operation，low solvent consumption，good sensitivity and stability，and it is suitable for large-scale indoor environmental pollution monitoring.关键词：liquid crystal monomers（LCMs）;dust;QuEChERS;gas chromatography-tandem mass spectrometry;emerging pollutant
- 112
- |
- 34
- |
- 0
发布时间：2024-03-13 - 摘要：In order to study the influence of 10 kinds of organic acids on the migration of heavy metals in the ceramic atomizing core of electronic cigarette，e-liquid with different contents of organic acids was prepared. The metal elements in the ceramic core migrated to the e-liquid and aerosol under accelerated aging conditions were measured by inductively coupled plasma mass spectrometry（ICP-MS），and the atomization efficiency of heavy metals in the ceramic core and the influence of organic acids were evaluated. The results showed that the detection limits of each element in the e-liquid and aerosol methods were ＜10 μg/kg，≤0.055 μg/100 puffs，respectively. Different types and contents of organic acids have different effects on the migration of heavy metals，the influences of citric acid，lactic acid，malic acid and acetic acid were relatively large. The atomization efficiencies of all elements in the aerosol ranges from 21.2% to 45.9%. Compared with the blank control group，citric acid，lactic acid，acetic acid，benzoic acid and malic acid had a significant impact on the increase of Ni content in aerosols（P<0.05），citric acid had a significant impact on the increase of Cu content in aerosols，and the five acids had no significant difference on other elements（P>0.05）. This method is accurate and reliable，and is suitable for evaluating the influence of organic acids in e-liquid and aerosol on the migration of heavy metals in ceramic cores.关键词：ceramic atomizing core;electronic cigarette;e-liquid;aerosol;heavy metals;inductively coupled plasma mass spectrometry（ICP-MS）
- 67
- |
- 58
- |
- 0
发布时间：2024-03-13 - 摘要：Triterpenoid saponins from Panax notoginseng and processed Panax notoginseng with hot sand were fast identified based on liquid chromatography-tandem mass spectrometry（LC-MS/MS） combined with molecular network technology. The processed Panax notoginseng was obtained using sand roasting at 170-220 ℃. Panax notoginseng and processed Panax notoginseng were extracted with 70% ethanol-water under reflux and the extractions were subjected to D101 macroporous resin eluting with 70% ethanol-water to afford the total saponins. The Agilent C18 column（100 mm×2.1 mm，3.5 μm） was selected for gradient elution with 0.05% formic acid-water and acetonitrile as the mobile phases，and mass spectrometry data of the reference substances and total saponins were collected in negative ion mode. After format conversion，the MS/MS data were uploaded to the Global Natural Products Social Molecular Network（GNPS） to establish a molecular network and the visualization was performed in Cytoscape 3.9.1. According to the similarity of reference substances，retention times，characteristic fragment ions，MS/MS fragmentation rules，and literatures，50 triterpenoid saponins were identified from Panax notoginseng and 60 triterpenoid saponins were characterized from processed Panax notoginseng with hot sand in which 23 saponins were found in both of them. There were 27 components in Panax notoginseng alone，including 11 malonyl-glucoside substituted saponins. The processed Panax notoginseng with hot sand contained 37 saponins alone，including 19 acetyl-glucoside substituted compounds. Eleven of these saponins were verified by reference substances. The quantitative analysis of ginsenoside Rb1，Rg1，Rg3，Rh4，Rk3，and notoginsenoside R1 in the total saponins of Panax notoginseng and processed Panax notoginseng with hot sand were determined by high performance liquid chromatography. The results showed that Panax notoginseng mainly contained primary saponins and the processed Panax notoginseng with hot sand mainly contained transformed saponins.关键词：Panax notoginseng;processed Panax notoginseng with hot sand;triterpenoid saponins;LC-MS/MS;molecular network
- 73
- |
- 31
- |
- 0
发布时间：2024-03-13 - 摘要：This work used a covalent organic framework TpBD-Me2（COF-TpBD-Me2） based dispersive solid-phase extraction fluorescence detection method to enrich and quantify α-asarone in human plasma. The optimal adsorption conditions of COF-TpBD-Me2 on α-asarone were also investigated，including the mass concentration of adsorbent，adsorption time，pH，desorption solvent and desorption time. Furthermore，the adsorption behaviour and mechanism were elucidated by static adsorption and adsorption kinetics studies. α-asarone exhibited a good linear range of 0.1-10 μg/mL，with correlation coefficients（r2） greater than 0.999，and the limit of detection（LOD） was 0.002 5 μg/mL. The proposed method applied for the α-asarone in actual human plasma samples for detection recoveries of spiked samples in the range of 92.2%-98.0% with relative standard deviations of 1.9%-3.8%. The results demonstrated that the method can effectively selectively enrich α-asarone in human plasma and accurate quantification. The methodology strategy provided a reference for the selective enrichment and rapid quantification of drug active ingredients in complex biological matrices.关键词：covalent organic framework;dispersive solid-phase extraction;adsorption;α-asarone;fluorescence detection
- 40
- |
- 21
- |
- 0
发布时间：2024-03-13 - 摘要：In this study，two types of fluorescent carbon dots were synthesized through solvothermal method by using waste polyester-cotton blended textile as the carbon source，in ethylene glycol and sulfuric acid solutions，respectively，to achieve the detection of Cr（Ⅵ） and Hg（Ⅱ） in solution. The morphology and structure composition of the carbon dots was analyzed by transmission electron microscope and infrared spectroscopy，and the electronic transition forms，optimal excitation wavelength，optimal emission wavelength，and luminescence types of the carbon dots were analyzed by UV-visible spectrophotometer and fluorescence spectrophotometer. Then，the detection performance of the two carbon dots was studied. The carbon dots obtained in the ethylene glycol system（named ETCCDs） could selectively detect Cr（Ⅵ），with a minimum detection limit of 0.093 mg/L and the detection mechanism was fluorescence internal filtration effect. The carbon dots prepared in the sulfuric acid system（named WTCCDs） could selectively detect Hg（Ⅱ） with a detection limit of 0.018 µmol/L，and the detection mechanism was caused by energy transfer. Furthermore，Cr（Ⅵ） and Hg（Ⅱ） in actual water samples were detected，verifying the practicality of these two carbon dots. The fluorescent carbon dots designed based on polyester cotton blended fabrics not only achieve the detection of two heavy metal ions，but also provide reference significance for the regeneration and utilization of waste textiles.关键词：fluorescent probe;polyester-cotton blend;detection;Cr（Ⅵ）;Hg（Ⅱ）;carbon dots
- 38
- |
- 28
- |
- 0
发布时间：2024-03-13 - 摘要：As the basic unit of protein，amino acids（AAs） are important living substances. The study of their monomer carbon isotope is of great significance in the fields of biogeochemistry，ecology，organism metabolism and environmental science. In this paper，we optimized the extraction and purification processes of AAs from sea cucumber and seaweed. After derivatization by N-pivaloyl-O-isopropyl（NPP） method，the concentration and carbon isotope composition were tested by gas chromatography-mass spectrometry（GC-MS） and gas chromatography-combustion-isotope ratio mass spectrometry（GC-C-IRMS）. The results showed that 15 AAs were successfully separated，the recoveries were between 46.4% and 96.3%，and the linear relationship of each amino acid was good in the range of 1-16 μmol/L（r2=0.987-0.999）. The standard deviations of δ13C values of 15 AAs monomer derivatives were less than 0.30‰（n=10），and the average error of δ13C was ± 0.24 ‰ in the concentration range of 0.6 - 2.0 mmol / L. The detection limit of this method was 0.6 nmol. The δ13C values of AAs monomers in sea cucumber and seaweed samples ranged from -8.58‰ to -31.10‰，and -13.76‰ to -30.53‰，respectively，and the standard deviations were all within 0.33‰，which could meet the accuracy requirements of carbon isotope analysis of AAs monomers in organisms.关键词：gas chromatography-combustion-isotope ratio mass spectrometry（GC-C-IRMS）;N-pivaloyl-O-isopropyl（NPP）;amino acid;carbon stable isotope
- 68
- |
- 28
- |
- 0
发布时间：2024-03-13
Scientific Papers
- 摘要：A method for determination of 27 amino acids in sports nutrition foods was established based on magnetic dispersive solid phase microextraction purification，coupled with ultra-high performance liquid chromatography-quadrupole-orbitrap high-resolution mass spectrometry（UHPLC-Q-Orbitrap HRMS）. Through optimization of the liquid chromatography conditions，mass spectrometry conditions，and sample pretreatment process，analysis and determination of 27 target analytes were achieved within 20 minutes. The sample was subjected to vortex oscillation，ultrasonic extraction，dispersive solid phase microextraction purification with magnetic graphene oxide.The analytes were separated by a Thermo Accucore HILIC chromatographic column，and eluted with a gradient of 0.1% formic acid water solution containing 5.0 mmol/L formic acid ammonium and 0.1% formic acid acetonitrile containing 5.0 mmol/L formic acid ammonium as the mobile phase，followed by electrostatic trap high-resolution mass spectrometry detection. The results showed that the 27 target compounds had good linear correlations within a certain mass concentration range with correlation coefficients（r2） greater than 0.99，and the quantitation limits of the method were 0.10-0.25 mg/kg，with recoveries ranged of 70.0%-93.0%. The intra-day relative standard deviations（RSDs，n=6） ranged of 1.6%-10%，and the inter-day RSDs（n=5） ranged of 1.4%-5.2%. The analysis method is highly efficient，sensitive，accurate and reliable，and is suitable for the determination of 27 amino acids in sports nutrition foods.关键词：ultra-high performance liquid chromatography-quadrupole-orbitrap high-resolution mass spectrometry;magnetic graphene oxide;magnetic dispersive solid phase microextraction;sports nutrition food;amino acids
- 45
- |
- 26
- |
- 0
发布时间：2024-03-13 - 摘要：A hydrolytic extraction method combined with gas chromatography-mass spectrometry（GC-MS） method for the determination of alkyl ketene dimer sizing agent in paper was developed. The paper samples were hydrolyzed with 1 mol/L sodium hydroxide solution in a constant temperature water bath at 70 ℃ for 2 h，and then extracted with methylene chloride for 1 h. After the filtration of the extraction solution，the analytes were measured on GC-MS，characterized by retention time and characteristic ion pairs，and quantified by internal standard method. The results showed that there were good linear relations for the 14-heptacosanone，16-hentriacontanone and 18-pentatriacontanone in the range of 1.0-50 mg/L，1.0-50 mg/L，and 2.5-50 mg/L，respectively，with correlation coefficients（r2） more than 0.98. The limits of detection for the analytes were 0.1 mg/L，0.5 mg/L and 2.0 mg/L，and the limits of quantitation were 0.5 mg/L，1.5 mg/L and 5.0 mg/L，respectively. Based on the average retention，the extraction recovery of alkyl ketene dimer from poplar fiber hand-made paper with sizing content of 1% were 34.9%-60.9%. The method was used to detect 40 kinds of different brands of copy paper. According to the characteristic substances，the ratio of raw materials for alkyl ketene dimer，and total ketone content in paper，40 kinds of paper samples were divided into three categories. The method is simpler and milder than existed ones，which is suitable for the examination and comparison of paper material evidence in the field of forensic science. Besides，this method can provide a new reference for the research and judgment of paper sizing method，manufacturer tracing，and formation age inference.关键词：alkyl ketene dimer;sizing agent;gas chromatography-mass spectrometry;paper examination;forensic science
- 44
- |
- 25
- |
- 0
发布时间：2024-03-13 - 摘要：A liquid chromatography-tandem mass spectrometric method was developed for the determination of diazepam and its metabolites（nordazepam，oxazepam and temazepam） in aquaculture water，plant，sediment and crucian carp. The aquaculture water was filtered through 0.45 μm glass fiber membrane，adjusted to pH 8.0 with ammonia，and then purified by reverse phase solid phase extraction column（HLB）. The plants and sediments were extracted by salting out and then cleaned up by QuEChERS method before injection. The crucian carp samples were also extracted by salting out，cleaned up by solid phase extraction column（Prime HLB），and then injected for analysis.The analytes were separated by Luna C18 column（100 mm×2.1 mm，1.6 μm），determined in multiple reaction monitoring（MRM） mode，and quantified by external standard calibration method. The results showed that the linear ranges of diazepam and its three metabolites were 0.1-10 μg/L（r2 > 0.999）. The limits of detection and quantitation in aquaculture water were 1.0-1.2 ng/L and 5.0-6.0 ng/L，respectively. The limits of detection and quantitation in plants，sediments and crucian carp were 0.03-0.10 μg/kg and 0.10-0.25 μg/kg，respectively. The recoveries of diazepam and its metabolites at three spiked levels ranged from 83.4% to 106%，and the relative standard deviations（RSDs，n=6） were 1.2% to 9.4%. The method was successfully applied to the detection of diazepam and its metabolites in aquaculture water，sediments，plants and crucian carp samples. It can provide methodological support for tracing diazepam pollution.关键词：diazepam and its metabolites;aquaculture environment;plants;carp;liquid chromatography-tandem mass spectrometry（LC-MS/MS）
- 61
- |
- 18
- |
- 0
发布时间：2024-03-13 - 摘要：A rapid quantitative model was established for the changes in polysaccharide content of Polygoni Multiflori during the steaming process using near infrared spectroscopy（NIRS） in this study. The polysaccharide content of different steamed Polygoni Multiflori samples at different steaming times was determined using the anthrone-sulfuric acid method，and a model was built using the collected NIRS data. The evaluation criteria for the model included the correlation coefficient of the calibration set（R2c），the correlation coefficient of the prediction set（R2p），the root mean square error of cross validation（RMSECV），and the root mean square error of prediction（RMSEP）. The effects of different preprocessing methods and variable selection methods were investigated. The results showed that the polysaccharide content of Polygoni Multiflori initially increased and then decreased，eventually reaching a steady state with prolonged steaming time. The partial least squares regression model built using smoothing，variable standardization，and random frog leaping variable selection methods achieved satisfactory performance with R2c of 0.96，RMSECV of 0.74，R2p of 0.96，and RMSEP of 0.28. The relative deviation of external prediction was less than 3.0%. The established quantitative model for polysaccharide content exhibited high quality and strong prediction ability，providing reference for the standardization and quality evaluation of the steaming process of Polygoni Multiflori.关键词：Polygoni Multiflori;polysaccharide;near infrared spectroscopy;nondestructive determination;steaming process
- 47
- |
- 34
- |
- 0
发布时间：2024-03-13 - 摘要：The water can soften and dissolve rocks，it is very important to predict the water content of rocks accurately for deep underground mining of geotechnical engineering. In this paper，the mid-infrared spectroscopy was applied to analyze the water content of sandstone. The relationship between the mid-infrared spectral characteristics and water content of sandstone samples was studied. The effective feature vectors were extracted by various pretreatment methods，and an mid-infrared spectral prediction model for water content of sandstone was constructed. The results showed that the correlation coefficients R2 between the predicted and measured values on the test set for multiple scattering correction+partial least squares，feature vector extraction+random forest and first order differential+support vector machine were 0.985，0.995 and 0.951，respectively. The root-mean-square errors were 0.074，0.022 and 0.137. All of them can predict the water content of sandstone well，and the prediction model combining feature vector and random forest had the best effect. This method realizes non-destructive and rapid water content analysis of sandstone by mid-infrared spectroscopy，providing a reference for water prediction of sandstone in geological engineering.关键词：mid-infrared spectrum;sandstone;water content;forecast
- 38
- |
- 26
- |
- 0
发布时间：2024-03-13 - 摘要：In the rapidly advancing life science fields such as metabolomics and proteomics，stable isotope labeling reagents that are non-radioactive and have similar physiochemical properties with unlabeled compounds have been widely utilized. Biological fermentation is one of the major synthesis approaches for labeled amino acids. In this study，we have established an accurate，robust，and rapid method to determine the isotope abundance of the amino acids in the fermentation broth to aid in early assessment of batch quality and optimization of fermentation conditions and amino acid yield. A Hypersil Gold Vanquish column（100 mm × 2.1 mm，1.9 μm） with water and methanol containing 0.1% formic acid as mobile phase and a liquid chromatography-high resolution mass spectrometry（LC-HRMS） system in positive ion mode were used for the study. The isotopic abundance of L-isoleucine-15N samples was determined to be 98.58%，closely matching the indicated value（>98%），with a relative standard deviation of 0.03%，demonstrating excellent accuracy and precision for the method. Then the method was successfully applied to determine the isotopic abundance and distribution of L-isoleucine in Brevibacterium flavum labeled with 15N or 13C. The proposed method is simple to perform，convenient，highly sensitive，and robust，holding wide application potentials in synthetic biology and research in stable isotope traced metabolic pathways.关键词：stable isotope labeled amino acid;liquid chromatography-high resolution mass spectrometry（LC-HRMS）;Brebvibacterium flavum;isotope distribution and abundance
- 20
- |
- 13
- |
- 0
发布时间：2024-03-13
Experimental Techniques and Methods
- 摘要：Atmospheric fine particulate matter（PM2.5），as one of the major pollutants that seriously affect the human health. PM2.5 are highly dynamic in the environment，and their chemical composition，morphology，and sources are extremely complex. It is a challenging task that making multidimensional characterization，e.g.，real-time analysis，particle size characterization，precise source tracing，and in-situ identification，on the critical components of PM2.5 in complex environmental matrix. Inductively coupled plasma mass spectrometry（ICP-MS） is a powerful tool for PM2.5 analysis due to its high sensitivity，high throughput，wide linearity range. In recent years，the ICP-MS techniques showed a rapid development，e.g.，optimization in sampling system，single particle analysis，collision and reaction cell，multi-collector，and laser ablation technique. In this way，we can perform real time and in-situ characterization on PM2.5. Moreover，the diameter，particle number，and even isotopic fingerprints of PM2.5 can also be identified based on ICP-MS. Thus，this study reviews the recent advances in multidimensional characterization on PM2.5 with ICP-MS，summarizes the principle and notes in using ICP-MS. Moreover，we also provide a perspective for future research in multidimensional characterization on PM2.5 with ICP-MS. This review enhances the tool box for studying the transformation，health effect，and source racing of PM2.5.关键词：inductively coupled plasma mass spectrometry（ICP-MS）;PM2.5;single particle analysis;in-situ analysis;isotope analysis
- 76
- |
- 27
- |
- 0
发布时间：2024-03-13
Review
- Address：100 Xianlie Middle Road, Guangzhou Postal code：510070
- Tel：020-87684776,37656606 Fax：020-87684776 Email：fxcsxb@china.com
- Technical support is provided by Beijing Founder electronics co., LTD 粤ICP备12017312号-3
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0