最新刊期
卷 36 ， 期 10 ， 2017
- 摘要：A method was established for the simultaneous determination of 3-chloropropanol esters(3-MCPDE) and glycidol esters(GE) in different types of oil and lipid food products by gas chromatography-mass spectrometry(GC-MS).Optimizations on extraction, transesterification, derivatization and the chromatographic conditions of GC-MS of samples were completed. Limits of quantitation(LOQs) of the method for four types of food products,i.e. vegetable oils, milk powder, fried and puffed foods and bakery foods, were 100,25,125,20μg/kg, respectively, the total mean recoveries were in the range of 81.2%-109% with the relative standard deviations(RSD，n=6) of 0.77%-7.3% and the correlation coefficients(r) higher than 0.999.Moreover,the 3-MCPDE and GE contents in 30 oil and lipid food products were determined to be in the range of no detected-8.04mg/kg.The developed method could meet the demand for routine food inspection, in particular for the quantitative and qualitative determination of 3-MCPDE and GE in oil and lipid foods with its high efficiency, high sensitivity and strong workability.关键词：gas chromatography-mass spectrometry(GC-MS);food;3-chloropropanol esters;glycidol esters;determination
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发布时间： - 摘要：In this paper，the enrichment behavior of triclosan on multi-walled carbon nanotubes supported ferric hydroxide nanoparticles modified glassy carbon electrode was investigated by cyclic voltammetry with solid-phase microextraction.The extraction process was observed to follow the first-order kinetic equation based on Temkin isothermal adsorption model. The cyclic voltammogram of triclosan on the modified electrode showed an irreversible oxidation peak at about 0.558V.The linearity existed between the pH values and the oxidation peak potential indicated that the oxidation of triclosan was a transferred process of one electron accompanied by a proton. The oxidation peak current increased linearly with the increase of sweep rate，indicating that the oxidation reaction was controlled by surface adsorption. The linear relationship between the oxidation peak current and the logarithm of triclosan concentration in the range of 3.333×10-6-3.333×10-4mol/L could be used to determine the concentration of triclosan with the detection limit of 3.333×10-6mol/L.The method was used in detection of triclosan in hand sanitizers with good reproducibility and selectivity. Based on the cluster models of triclosan and ferric hydroxide nanoparticles，semi-empirical molecular orbital calculations were performed with PM7 in MOPAC2012.The thermodynamic and front orbit correlation coefficient results showed that a complex formed between triclosan and ferric ions was stable with the ΔG<0，and the electron transfer occurred in the formation of the triclosan complex.关键词：multi-walled carbon nanotubes;colloidal ferric hydroxide nanoparticles;triclosan;solid phase microextraction;glassy carbon electrode
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发布时间： - 摘要：A novel solid phase microextraction coating that contains perhydroxy cucurbit[5] uril was prepared by a sol-gel method. With 3-(2-cyclooxypropoxyl) propyltrimethoxysilane as cross-linking agent, perhydroxyl cucurbit[5] uril(Q[5](OH)10) and hydroxy-terminated poly(dimethylsiloxane)(OH-PDMS) were used as starting coating material to bond chemically to a fused-silica substrate to form a PDMS/Q[5](OH)10 coating by hydrolysis and polycondensation reactions. The surface morphology, microstructure and thermal stability of the obtained composite coating were characterized by scanning electron microscopy(SEM),Fourier-transform infrared spectrometry(FTIR),differential scanning calorimetry(DSC) and thermogravimetric(TG) analysis. The results showed that the coating has a large specific surface area, high thermal stability(360℃) and long lifetime. Its performance was tested using a homemade solid-phase microextraction coating fiber coupled with gas chromatography-mass spectrometry(GC-MS) to analyze volatile components in Rosmarinus officinalis L(ROL).The optimized solid-phase microextraction conditions included an extraction temperature of 80℃,an extraction time of 45 min and a 0.2000g sample. The volatile components were extracted by head solid-phase microextraction(HS-SPME) with a homemade extraction fiber, and identified by GC-MS. The relative content of each component was determined by area normalization. Twenty-five compounds in the ROL were identified. The main compounds are 1,8-cineole,camphor and α-pinene. The homemade fiber was compared with commercial fiber(PDMS/DVB/CAR).According to the quantity and content of the extracts from ROL, the extraction effect of the two kinds of fiber are equivalent, which indicated that the homemade novel fiber could be applied in the rapid detection of volatile components in plants.关键词：sol-gel technology;solid-phase microextraction coating;perhydroxy cucurbit[5]uril;gas chromatography-mass spectrometry;Rosmarinus officinalis L.(ROL)
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发布时间： - 摘要：A polydimethylsiloxane-glass(PDMS-Glass) based droplet digital polymerase chain reaction(ddPCR) chip was designed and fabricated,which was integrated with multiple functions. The PDMS-Glass chip was composed of two modules, of which one was a PDMS module for droplet generation, and the other was a multi-functional glass chamber for droplet collection, in situ ddPCR reaction and on-chip fluorescence readout. The PDMS module has a T-shaped structure with two channels, where the aqueous phase with sample was cut into water-in-oil droplets by the oil phase. The droplets generated by the PDMS-Glass chip have the advantages of high-throughput and high-frequency. About two million uniform droplets with an average diameter of 20μm could be produced within 30 min. The glass chamber was employed for droplets collection. No transfer of the droplets were required during the whole experiment. The droplets filled in the glass chamber were directly injected into the in situ PCR instrument for amplification reaction, where each droplet was a micro-reactor. The glass chamber provided the ddPCR with a good environment for ddPCR amplification, where the droplets kept stable after many times of thermal cycling. As one of the common pathogenic bacteria, Vibrio Parahemolyticus(VP) was selected to investigate the property of the PDMS-Glass based ddPCR chip on the aspect of absolute quantificaiton. The results showed that the ddPCR chip has a wide linear range of five-order-magnitude towards the genomic DNA of VP from 101 to 106 copies/μL. Meanwhile, the detected results by ddPCR approach have a good relativity with the theoretical expected DNA concentration.关键词：digital PCR;droplet microfluidic chip;pathogenic bacteria;Vibrio Parahemolyticus
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发布时间： - 摘要：A method was developed for the determination of low-ring polycyclic aromatic hydrocarbons(PAHs) and their derivatives in groundwater by liquid-liquid extraction(LLE) followed by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry(GC×GC-TOF MS).Compared with solid phase extraction(SPE),liquid-liquid extraction(LLE) shows higher extraction recoveries for samples, thus LLE was selected as the sample pretreatment method. The optimized results showed that the method has a good linear range of 0.1-1000μg/L with the correlation coefficients(r) higher than 0.99 for most of the targets, except for 1,2,3,4-tetrahydronaphthalene(r=0.9872) and biphenyl(r=0.9899).The spiked recoveries of the targets ranged from 63.3% to 111%with relative standard deviations less than 9.5%(RSD, n=6), except for quinoline(RSD，24.9%),and the detection limits ranged from 1.63ng/L to 14.7ng/L.The method was applied in the determination of low-ring PAHs and their derivatives in real groundwater samples from Hebei province, and the pollutants in two-thirds of samples were detected with the maximum concentration of 353ng/L.关键词：Low-ring PAHs;derivatives;GC×GC-TOF MS;groundwater
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发布时间： - 摘要：The feature selection algorithm based on the combination of random forest and game theory was proposeed in this paper as noise and redundant information in the near infrared spectroscopy would lead to the low recognition rate of a model.This algorithm was first used to measure the feature significance according to the random forest and select some features related to classification,then compute the weights of selected characters by using the improved Shapley values and mutual information computed to remove redundant information from the weighted feature set and get the optimal feature subset.To validate effectiveness of this algorithm,the tobacco leaf production area identification model was established.The experimental results indicated that the algorithm proposed in this paper had a good recognition on the area of tobacco leaf production with a recognition rate of 95.88%.关键词：NIR spectroscopy;random forest;feature selection;shapley value;production area identification
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发布时间： - 摘要：The dispersed multiwalled carbon nanotubes with carboxyl(f MWCNTs) were firstly dropped on the glass carbon electrode to allow a f-MWCNTs menbrance formed on the electrode surface,then chitosan(CS) was electrodeposited on the surface of the eletrode via potentiostatic method to develop a CS/f-MWCNTs/GCE which was used for the chiral recognition of tryptophan enantiomers.The surface morphology of the eletrode was characterized via scanning electron microscopy(SEM).Cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) were used to investigate the electrochemical behavior difference of the modified electrode.Differential pulse voltammetery(DPV) was employed to investigate the stereospecific recognition of tryptophan(Trp) enantiomers with a separation coefficient of 2.38.The results showed that the CS/f MWCNTs/GCE displayed a more strong DPV response for L-Trp than that for D-Trp in the linear range of 8.0×10-6-4.0×10-3 mol/L with a detection limit of 5.0×10-6 mol/L(S/N=3).Meanwhile,it provided a beneficial reference for the discrimination of other chiral enantiomers.关键词：chitosan;tryptophan;enantioselective recognition;electrochemical method
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发布时间： - 摘要：A new analytical method was developed for the determination of four polycyclic aromatic hydrocarbons(PAHs) in environmental water and soil samples by magnetic polyphenylene conjugated microporous polymer(PP-CMP)enrichment coupled with surface-enhanced Raman spectroscopy(SERS).The PAHs in environmental water and soil sample were enriched with magnetic polyphenylene conjugated microporous polymer via hydrophobic interaction and π-π stacking effect,then eluted with methanol.In the experiment,desorption-solvent,extraction-time and desorption-time were investigated.The results showed that good linearities between Raman intensities and concentrations were in the range of 0.1-10 μg/L for anthracene,pyrene,fluoranthene and benzo［α］pyrene with the limits of detection of 0.03 μg/L.The spiked recoveries for four PAHs were in the range of 71.6%-115.8% with their RSDs no more than 13.7%.The results indicated that this method has the advantage of high-sensitivity,and could meet the requirements for monitoring four PAHs in real water and soil samples.关键词：polyphenylene conjugated microporous polymer;extraction;polycyclic aromatic hydrocarbons;surface-enhanced Raman spectroscopy
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发布时间： - 摘要：A method was developed for the rapid detection of 8 hormones，6 β-receptor agonists and 4 antibiotics growth promoting agents in bovine liver by PRiME HLB solid-phase extraction/ultra performance liquid chromatography tandem mass spectrometry(UPLC-MS/MS).The chromatographic separation conditions，MS/MS detection parameters and sample pretreatment were optimized，respectively.The sample was firstly added NH4OAc buffer solution(pH 5.2)，and hydrolyzed with a mixed solution of β-glucuronidase/sulfatase，then extracted with methanol(MeOH) and acetonitrile(ACN)-MeOH(90∶10，by volume) step by step，finally purified with PRiME HLB.The effluent was collected and concentrated to dryness，and redissolved with ACN-water(3∶7，by volume) for UPLC-MS/MS detection.The results showed that 18 kinds of compounds had good linear relationships in the range of 1.0-100.0 μg/L with their correlation coefficients higher than 0.990.The detection limits(LODs) ranged from 0.07-0.78 μg/kg，and the quantitation limits(LOQs) ranged from 0.23-2.58 μg/kg.The average recoveries of 18 compounds at three spiked levels(0.5，1.0，5.0 μg/kg) were in the range of 67.5%-102.0%with relative standard deviations(RSDs) less than 15%.The method was simple，rapid and accurate，and was suitable for the simultaneous detection of 18 growth promoting agents in animal tissues.关键词：UPLC-MS/MS;PRiME HLB solid-phase extraction;growth promoting agents;bovine liver
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发布时间： - 摘要：The water distribution and state change of dried shrimp meat during rehydrated process at 25 ℃ were investigated by LF-NMR and MRI,and the correlation between NMR parameters and texture,rehydration ration was analyzed to construct the predicted mode by linear regression analysis.Three water components,i.e.bound water,immobilized water and free water were observed in dried shrimp meat during the rehydrated process.The contents and mobility of immobilized water and free water increased as the extension of the rehydration time,while that of bound water did not change obviously.The results of MRI indicated that the water absorbed by the dried shrimp mainly was components with short relaxation time,and permeated from head to body and tail.Good linear correlation was observed between the NMR parameters (T22，T23，A22，A23 and ATotal) and texture profile analysis parameters including the hardness,chewiness,springiness,cohesiveness and rehydration ratio of dried shrimp meat(R2≥0.613),which could provide a rapid and non-destructive method to predict the quality of dried shrimp meat during rehydrated process.关键词：LF-NMR;MRI;dried shrimp meat;rehydration;water state;quality
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发布时间： - 摘要：In the absence of ion-pair reagents or high-salt buffer condition，a novel method for the quantitative analysis of disodium ethylenediaminotetraacetic acid in flour and its products by high performance liquid chromatography was developed，employing hydrophilic C18 reversed-phase liquid chromatography column and methanol-water system as mobile phase.Samples were extracted with aqueous solution，and reacted with ferric chloride by ultrasound irradiation to product stable derivative which was cleaned up with trichloromethane.To determine ethylenediaminotetraacetic acid disodium in flour and flour products，the analytes were determined by high performance liquid chromatography with a wavelength of 260 nm and a hydrophilic C18 reversed phase liquid chromatography column using mobile phases of pH 4.0 methanol and aqueous solution(10∶90，by volume).Under the optimal conditions，the calibration curves of the analytes were linear in the concentration range of 1.0-50.0 mg/L with the correlation coefficients of 0.999 6.The limits of quantification(LOQs) were 10.0 mg/kg，and the limits of detection(LODs) were 3.0 mg/kg.At spiked levels of 10.0-200 mg/kg，the average recoveries of spiked samples ranged from 95.0%to 103%，with relative standard deviations between 4.0%and 6.3%.The method could meet the requirement for the rapid screening and quantitative analysis of disodium ethylenediaminotetraacetic acid in flour and its products.关键词：disodium ethylenediaminotetraacetic acid;flour products;high performance liquid chromatography;hydrophilic C18 reversed-phase liquid chromatography column
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发布时间： - 摘要：A rapid and nondestructive method was established for the analysis of the volatile organic compounds in edible vegetable oils by headspace/gas chromatography-tandem ion mobility spectrometry(GC-IMS).56 sesame oil,rapeseed oil and camellia oil samples were taken as the research objects.2 mL tested sample was put into the standard sample bottle which was sealed with a magnetic cap for direct GC-IMS analysis.The results showed that the characteristic peaks in GC-IMS 3D spectra corresponding to volatile organic substances can effectively characterize the sample information areas of different types of vegetable oils.With the sectional intensities of 40 characteristic peaks in corresponding three-dimensional spectra as variables,the principal components analysis(PCA) algorithm was used to reduce information dimensionality,establishing the training model for discriminating the type of vegetable oil by kNN algorithm,and the recognition rate was up to 100%,only 1 camellia oil sample was judged as sesame oil in the predicted set,and the prediction set recognition rate was 94.44%.GC-IMS technique is simple,rapid and nondestructive,and could be used for the rapid identification of agricultural products and other foods such as edible vegetable oils.关键词：gas chromatography-ion mobility spectrometry(GC-IMS);edible vegetable oil;classification;chemometrics
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发布时间： - 摘要：A poly-(MA)-ERGO hybrid film modified electrode was fabricated by using cyclic voltammommetry.The electrochemical behaviors of dopamine(DA),uric-acid(UA)and ascorbic acid(AA)were investigated,respectively.The results showed that the modified electrode exhibited an excellent electrocatalytic activity toward the electrooxidation of DA and UA,and had a superior selectivity in the determination of DA,UA in the presence of AA.Under the optimum conditions,the calibration curves for DA and UA were linear in the range of 1.0×10-8-5.0×10-6 mol?L-1 with the detection limit(3sb)of 5.0×10-9 mol?L-1.关键词：Poly-(melamine);graphene;uric acid;dopamine;ascorbic acid
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发布时间： - 摘要：A novel method for the detection of sodium tanshinon ⅡA sulfonate was developed based on the inhibition effect of sodium tanshinon ⅡA sulfonate on luminol-H2O2-silver nanoparticles(AgNPs)chemiluminescence(CL) under alkaline condition.The optimal experiment-conditions were established by optimizing the concentration of CL substrates,reaction medium and its concentration,and the concentration of AgNPs.The possible mechanism of the CL system was also investigated.Under the optimal conditions,the CL intensity was inversely proportional to logarithm value of sodium tanshinon ⅡA sulfonate concentration in the range of 5.0×10-6-0.08 mol/L with a detection limit of 9.38×10-7 mol/L and a detection time of 20 s.With a considerable sensitivity and a wide detection range,the proposed method could be applied in the simple and fast detection of sodium tanshinon ⅡA sulfonate in the injection solution with satisfactory results which are in good agreement with the reference values obtained by high performance liquid chromatography.关键词：chemiluminescence;silver nanoparticles;luminol;sodium tanshinon ⅡA sulfonate
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发布时间： - 摘要：A new dual-wavelength superposition absorption spectrometry was established for the rapid and accurate determination of metoprolol tartrate in drug.In pH 4.55 acidic Tris-hydrochloric acid media and 586 nm-740 nm,metoprolol tartrate reacted with chlorophosphonazo Ⅲ to form an ionic association complexes with two obvious positive absorption peak.The maximum positive absorption wavelength located at 614 nm,and the second largest positive absorption wavelength was at 664 nm.The apparent molar absorptivity(κ) were 6.03×104 L/(mol?cm)(614 nm) and 5.37×104 L/(mol?cm)(664 nm),respectively.Metoprolol tartrate obeys Lombard Beers law in the range of 0.2-8.6 mg/L,and the detection limits were 0.13 mg/L(614 nm) and 0.15 mg/L(664 nm),respectively.When the double wavelength superposition absorption spectrometry was used to determine the concentration of metoprolol tartrate,its apparent molar absorptivity(κ) could be achieved to be 114×105 L/(mol?cm),and the detection limits was 0.072 mg/L.The optimum chromogenic reaction conditions,effects of the coexistence material and absorption spectral characteristics were studied.It was found that the apparent molar absorptivities for the single wavelength and dual wavelength superposition absorption spectra of the reaction system were 5.37×104-1.14×105 L/(mol?cm).The method was applied in the determination of the content of metoprolol tartrate in commercially available metoprolol tartrate medicine with the spiked recoveries and RSD(n=6) found were in the ranges of 98.0%-101%and 1.8%-2.3%,respectively.关键词：metoprolol tartrate;chlorophosphonazo Ⅲ;drug;dual-wavelength;absorption spectrometry
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发布时间： - 摘要：A high performance liquid chromatographic(HPLC) method with microwave hydrolysis derivation was developed for the simultaneous determination of 17 amino acids in feed.The method was based on pre-column derivatization with 2,4-dinitro-chlorobenzene.The compounds were separated on a C18 column.And the conditions of microwave hydrolysis were optimized.The detection was performed using a diode array detector at 360 nm.The calibration curves of 17 amino acids all exhibited good linearities in the range of 2.5-50 mg/L.The correlation coefficients(r2) for the determination varied between 0.990 7 and 0.999 9 with the relative standard deviations(RSDs) of 0.88% to 4.2%,and the recoveries of 17 amino acids were in the range of 90.6%-107.2% with the limits of detection of 0.15-2.37 mg/L.The results showed that the results of microwave hydrolysis in 16 min at 150 ℃ are basically the same as those of traditional heating hydrolysis(110 ℃,24 h).With the advantages of short analysis time,high sensitivity,the method could be used for the determination of amino acids in feed.关键词：microwave hydrolysis;amino acid;high-performance liquid chromatography(HPLC);pre-column derivatization;feed
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发布时间： -
Determination of Tetrabromobisphenol A in Textiles by Liquid Chromatography-Tandem Mass Spectrometry
摘要：A method was developed for the determination of tetrabromobisphenol A in textiles by ultra-fast liquid chromatography-tandem mass spectrometry(UFLC-MS/MS) with solid phase extraction.The sample was extracted with methanol by ultrasonic wave,and purified on a C18-SPE cartridge.The analyte was determined by the electrospray ionization-mass spectrometry in multiple reaction monitoring(MRM) mode.The qualitative and quantitative analysis were based on the retention time and characteristic ion pairs of the analyte.There was a linearity for tetrabromobisphenol A in the range of 1.0-100.0 μg/L,and the limit of quantification(LOQ) was 1.0 μg/kg.The average recoveries were in the range of 80.9%-95.3% with the relative standard deviations of 2.3%-5.9%.This method was rapid,accurate and sensitive,and was suitable for the analysis of tetrabromobisphenol A in textiles.关键词：liquid chromatography coupled with tandem mass spectrometry;textiles;tetrabromobisphenol A- 553
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发布时间： - 摘要：A high performance liquid chromatography method for the determination of pydiflumetofen residues in watermelon was developed using dispersive solid phase extraction and dispersive liquid-liquid microextraction as sample preparation methods.The samples were extracted with acetonitrile and water solution,purified with primary secondary amine as sorbents,and concentrated into 1,1,2,2-tetrachloroethane by dispersive liquid-liquid microextraction.The extracts were analyzed by high performance liquid chromatography.The conditions affecting the purification efficiency of the dispersed solid phase extraction,including the extraction solvent and the type of adsorbent were optimized.Factors affecting the extraction efficiency such as type and volume of extraction solvent,volume of dispersive solvent and salt concentration,were investigated.The results indicated that the calibration curves for the analytes were linear in the concentration range of 0.01-5 mg/L with the correlation coefficients of 0.999 9.The limits of quantification(S/N=10)were 0.01 mg/kg.The mean recoveries at three concentration levels of 0.01,0.1,1 mg/kg were in the range of 89.2%-94.5%with the relative standard deviations below 8.7%.With the advantages of simplicity,high efficiency and sensitivity,the proposed method was applicable for the analysis of pydiflumetofen residues in watermelon samples.关键词：pydiflumetofen;dispersive solid-phase extraction;dispersive liquid-liquid microextraction;watermelon;high performance liquid chromatography
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发布时间： - 摘要：There are extremely low contents of free fatty acids in biological matrices.Lacking of ionized groups in the chemical structures of free fatty acids leadsnhance the response of mass spectrometry by modifying the chemical structures of free fatty to the poor ionization and sensitivity in mass spectrometry analysis.It is an effective way to e acids through derivatization technique.In recent years,chromatography-mass spectrometry combined with the chemical derivatization has been widely used in fatty acid analysis.The progresses in analysis of free fatty acids by chromatography-mass spectrometry based on chemical derivatization and its application are summarized in this paper.关键词：free fatty acids;chemical derivatization;chromatography;mass spectrometry;research progress
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发布时间： - 摘要：Polychlorinated biphenyls(PCBs) are one of the persistent toxic organic pollutants in the environment,which have caused serious harm to the ecological environment.Many monitoring methods for PCBs have been developed rapidly because the researchers have paid more and more attention on their perniciousness.The main analytical methods for PCBs at home and abroad in recent years are summarized in this paper,especially the investigation on determination of PCBs using electrochemical sensors.and the insufficients of these researches are also pointed out.The foreground of electrochemical sensors in application of determining PCBs are prospected．关键词：Polychlorinated-biphenyls;electrochemical-sensor;analytical-method;research progress
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