最新刊期
卷 34 ， 期 6 ， 2015
- 摘要：A method was developed and applied to determine the residual amounts of 286 pesticides（organophosphorus，organochlorine，pyrethroid，carbamate and other pesticides） in tea and its products by gas chromatography-mass spectrometry（method Ⅰ），and an other method was applied to determine 9 kinds of strongly polar organophosphorus pesticides in tea and its products by gas chromatography（method Ⅱ）．For method Ⅰ,the residues were extracted from homogenized tissue with ethyl acetate assisted by ultrasonication．The clear supernatant liquid purified by solvent transfer technique and solid phase extraction（Cleanert TPT column） was ready for GC-MS analysis．For method Ⅱ，the residues were extracted from homogenized tissue using acetonitrile assisted by ultrasonication．The supernatant was purified by solid phase extraction（Cleanert TPT column） prior to GC analysis．Determinations were performed by GC-MS in selected ion monitoring（SIM） mode and GC method with flame photometric detector（FPD），then external standard method was used in the quantification．The methods were convenient and rapid after the conditions of pretreatment and determination were investigated．Under the optimal conditions，the quantitation limits of two methods（S/N≥10） for pesticides were in the range of 0.01-0.10 mg/kg.The linear ranges were between 0.01 mg/L and 1.00 mg/L with correlation coefficients（r2） larger than 0.99．Tests for recovery were carried out by addition of standards at concentration of 0.10 mg/kg，the recoveries of method I were in the range of 51%-135%，among which the recoveries for 88.3% pesticides were between 70% and 110%，and the recoveries of method Ⅱ were in the range of 68%-99%，while the relative standard deviations were in the ranges of 3.7%-18% and 3.5%-8.2%,respectively．The methods are easy，fast and sensitive,and could meet the requirements of the multiresidual analysis in tea and its products．关键词：gas chromatography（GC）;gas chromatography-mass spectrometry（GC-MS）;sample pretreatment;multiresidual analysis;tea;tea powder
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发布时间： - 摘要：A new analytical method was developed for the determination of 167 pesticides in animal-originated foods,including meat and aquatic.The pesticide residues were extracted from animal-originated samples with acetonitrile,and purified by gel permeation chromatography and solid-phase extraction（Carb-NH2）.The detection could be achieved by gas chromatography-tandem mass spectrometry（GC-MS/MS）,and the quantification was performed using the external standard calibration.The experimental results showed that the linear ranges for 167 pesticides were in the range of 1-200 μg/L with correlation coefficients larger than 0.994.The limits of detection and quantitation for 167 pesticides in the spiked blank pork sample were in the ranges of 0.3-3 μg/kg and 1-10 μg/kg,respectively．The spiked recoveries at levels of 0.01 mg/kg and 0.04 mg/kg using pork samples as blank matrix were in the range of 66.4%-111.5%,and the relative standard deviations（RSDs） were 1.3%-17.8%.The method has the advantages of accuracy,reliability,high sensitivity and efficient cleanup procedure,and could meet the demand for pesticide routine analysis.关键词：pesticides residues;gas chromatography-tandem mass spectrometry（GC-MS/MS）;gel permeation chromatography;solid-phase extraction;animal-originated food
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发布时间： - 摘要：An UPLC-QTOF/MS method for the simultaneous determination of xylazine and 2,6-dimethylaniline in blood and urine was developed.The samples were extracted with ethyl acetate-hexane（1∶1,by volume）,then separated on a C18 reversed-phase column and analyzed by ultra high performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry with positive electrospray ionization interface operating in the full scan ion mode.By software,the target compound was confirmed by the comparison of theoretical accurate moleculer mass,isotopic pattern abundance and product ion characteristics.The limits of detection for xylazine in blood and urine were 0.2, 0.1 μg/L,respectively,and the limits of quantitation were 0.6,0.3 μg/L,respectively.The limits of detection for 2,6-dimethylaniline in blood and urine were 0.5,0.3 μg/L,respectively,and the limits of quantitation were 1.5,1.0 μg/L,respectively.The recoveries were between 72.5% and 87.8%,with RSDs of 6.8%-9.7%.This method is rapid,sensitive and reproducible,and thus is suitable for the accurate quantitation of xylazine and its metabolite residues in real blood and urine samples.关键词：UPLC-QTOF/MS;xylazine;2,6-dimethylaniline;metabolites;blood;urine
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发布时间： - 摘要：In this work,Au NRs were synthesized by a two-step seed mediated growth method,and Au@Ag NRs were synthesized as SERS substrate through the chemical reduction method.The substrate was used to detect R6G as low as 10-18 mol/L.The Au@Ag NRs substrate has a good enhanced effect with enhanced factor of ca.1011.For the glucose deposited on the substrate with concentrations from 10-14 mol/L to 10-8 mol/L,the SERS signal intensity performs a linear change with logarithm concentrations of glucose.The experimental results showed that this method has a potential application prospect in ultra-trace glucose detection and semi-quantitative analysis.关键词：Au@Ag NRs;surface enhanced Raman scattering（SERS）;ultra-trace glucose;Rhodamine 6G（R6G）
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发布时间： - 摘要：A gas chromatography-mass spectrometric method with ultrasonic extraction was developed for the determination of taraxerol in mangrove sediments.The parameters including instrument condition,extraction,saponification,derivatization and data analysis were optimized.The analyte was separated by GC with an HB-5MS capillary column,then identified and quantified by the characteristic chromatograms properties and retention time.The component was separated completely from others,simultaneously identified and quantified with the standard curves.Quantitation using internal standard was based on the ratio of peak area of taraxerol derivative to peak area of internal standard derivative in the selected ion monitoring mode with electron impact source.The calibration curve was linear in the range of 5-100 μg/L,with a limit of quantitation of 0.5 μg/kg.The mean recoveries at 5,20,80 μg/L spiked levels were in the range of 81.2%-108.3%,with relative standard deviations of 1.9%-4.2%.The results showed that the developed method was sensitive,accurate and reproducible,and was suitable for the analysis of taraxerol in mangrove sediments.The study could provide scientific evidences for the management and protection of mangrove.关键词：gas chromatography-mass spectrometry(GC-MS);ultrasonic extraction;mangrove sediments;taraxerol
- 2022
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- 1154
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- 1
发布时间： - 摘要：GSH and Cys metabolites of microcystin-RR（MC-RR） were synthesized chemically by the monitoring of high liquid chromatography-electrospray ionization ion trap mass spectrometry（HPLC-ESI-ITMS）.Based on the enrichment and purification of AccuBOND C18 solid phase extraction（SPE）,the purity of these s-conjugates were higher than 95% by HPLC.In this study,the optimum reaction time and SPE cartridges treatment procedure were also studied,and 60 min was obtained as the optimal time for the s-conjugates synthesis.Extraction parameters including proportions of methanol in elution and washing solution were optimized,and the best mean recoveries were obtained by 90% methanol in elution after water washing,and their recoveries were in the ranges of 86.4%±1.5% and 90.2%±2.8% for GSH conjugates of MC-RR（MC-RR-GSH） and Cys conjugates of MC-RR（MC-RR-Cys）,respectively.These metabolites were subsequently confirmed by high phase liquid chromatography-electrospray ionization ion trap mass spectrometry（HPLC-ESI-ITMS）.The fragment ions of the metabolites of MC-RR were characterized,and the most aboundant ions for MC-RR-GSH and MC-RR-Cys were at m/z 673.6 and m/z 580.5,respectively,and these ions were further selected as precursor ion in MS/MS,while the product ions of these parent ions were at m/z 609.0/536.9 and 519.4/520.8,respectively.These purified metabolites were successfully applied as standard compounds in the quantification of MC-RR-GSH,MC-RR-Cys and MC-RR in the kidney of commom carp,and the contents(dry weight) were obtained at the levels of undetected（ND）,1.587 5,0.001 5 μg?kg-1,respectively.Futhermore,these metabolites could be used as significant reference substances in various studies,and the cleavage rules of MC-RR-GSH and MC-RR-Cys could provide some metabolic mechanism of microcystin-RR.关键词：MC-RR;MC-RR-GSH;MC-RR-Cys;HPLC-MS/MS
- 1892
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- 1165
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- 2
发布时间： - 摘要：Spectrophotometry is a general method used in enzymatic synthesis of glutathione（GSH） for tracking detection of reaction process.However，-SH from cysteine（Cys） could significantly interfere the results of GSH analysis.By multiple interference experiments and that of data processing and principle analysis，an anti-interference compensation method for elimination of interference caused by the reaction of alloxan and Cys was established.Anti-interference mechanism was set by introducing interference coefficient and compensation coefficient，building interference model and compensation algorithm.The absorbance and derivative of unknown sample were detected at 320 nm，then the data detected were taken into the flow chart of anti-interference compensation，the interference ratio and compensation coefficient were obtained，and the contents of GSH and Cys could be calculated.The detection results of new method showed that when the concentration of Cys in reaction liquid was not more than 4 times of that of GSH，the recoveries of GSH and Cys were in the ranges of 95%-100% and 78%-120%,respectively.The disturbance of Cys to the detection results could be eliminated.The standard equation for GSH concentration and absorbance is y=3.062 9x+0.000 1，r2=0.999 9.And compared with alloxan method，it has a significant enhancement in the anti-interference characteristics for detection of the contents of GSH and semi-quantitation of Cys on the basis of multiple relationships.It has a practical application value to the quantitative detection of GSH with non-separating cysteine in enzymatic synthesis of GSH.关键词：glutathione（GSH）;L-cysteine（Cys）;spectrophotometry;anti-interference compensation;rapid detection
- 2022
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- 1137
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发布时间： - 摘要：A fully automatic quantitative capillary electrophoresis system,which consists of a lab-made auto-sampler equipped with a 10 nL rotary type injector and a lab-made thermostat with cooling capacity,was developed.The accuracy and precision of the method were greatly improved compared with that of the conventional capillary electrophoresis（CE）.This article explored the feasibility of determination of benzoic acid,methyl p-hydroxybenzoate（MP）,ethyl p-hydroxybenzoate（EP）,propyl p-hydroxybenzoate（PP） and butyl p-hydroxybenzoate（BP） in cosmetics by fully automated quantitative micellar electrokinetic capillary chromatography（qMEKC）.The contents of MP,benzoic acid,EP,PP and BP in body cream and exfoliating gel were determined with a mobile phase of 15 mmol/L borax buffer and 100 mmol/L SDS（pH 9.3） mixture and a separation voltage of 20 kV.Good separation for the five preservatives was achieved under the optimal conditions,with RSDs of peak area lower than 2%.This method is rapid and accurate,and may be employed in the quality control of preservatives in cosmetics.关键词：quantitative capillary electrophoresis;nano-valve;automation;electric decoupler;quantitative micellar electrokinetic chromatography(qMEKC);preservatives
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发布时间： - 摘要：An ultra performance liquid chromatography-tandem mass spectrometric（UPLC-MS/MS） method was developed for the determination of six neonicotinoid pesticides（including imidacloprid,thiamethoxam,clothianidin,thiacloprid,acetamiprid and imidaclothiz） residues in honey by using salting-out homogeneous liquid-liquid extraction（SHLLE） and dispersive solid-phase extraction（d-SPE） as sample preparation method.The samples were extracted with acetonitrile,and acetonitrile phase was separated from sample solution through salting-out phenomenon with sodium chloride.The acetonitrile solution was purified by dispersive solid phase extraction with 0.22 μm filter membrane.The analytes were analyzed by ultra performance liquid chromatography-tandem mass spectrometry.Factors affecting the extraction efficiency were investigated,such as type and volume of extraction solvent and weight of sodium chloride.The performance of this method and matrix effects were evaluated under the optimal conditions.The results indicated that except for imidacloprid,the matrix effects of the rest neonicotinoid pesticides were more than 10%.The calibration curves for six pesticides were linear in the range of 0.2-100 μg/L with correlation coefficients（r2） of 0.998 1-0.999 7.The recoveries of six pesticides at three spiked levels of 1.0，5.0,50.0 μg/kg were in the range of 77.0%-106%,with relative standard deviations of 2.4%-19.8%.The limits of detection for this proposed method were in the range of 0.2-0.4 μg/kg and the limit of quantitation were all 1.0 μg/kg.With the advantages of simple pretreatment,short analysis time,high accuracy,high sensitivity and good reproducibility,the developed method is suitable for the determination of six neonicotinoid pesticide residues in honey.关键词：salting-out;homogeneous liquid-liquid extraction;dispersive solid-phase extraction;ultra performance liquid chromatography-tandem mass spectrometry（UPLC-MS/MS）;neonicotinoid pesticide;residue;honey
- 2062
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发布时间： - 摘要：A molecular imprinted polymer of cross linking chitosan was developed with Cr3+ as template molecule and glutaraldehyde as crosslinking agent.The adsorption properties of the molecular imprinted polymer were studied and the result showed that the imprinting crosslinked chitosan resin has good capacities of both absorption and selection for Cr3+.The imprinting crosslinked chitosan resin was used to prepare a solid phase extraction column,which was connected to a chemiluminescence analysis system as a CL cell.By using the catalytic action of Cr3+ on the chemiluminescence of luminol-H2O2 system,a new flow injection combined with on-line preconcentration and separation chemiluminescence method was set up for the determination of Cr3+.The linear range for the proposed method was in the range of 1.0×10-8-1.0×10-5 g/L.The detection limit was 3.7×10-9 g/L，and the relative standard deviation was 3.8%（ρCr3+=1.0×10-6 g/L,n=11）.After running more than 180 times,the separation efficiency of the solid phase extraction column did not change obviously.关键词：chitosan;molecular imprinted polymer;chemiluminescence;chromium;solid-phase extraction
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发布时间： - 摘要：A capillary electrochromatography-electrospray-time of flight/mass spectrometric（CEC-ESI-TOF/MS） method for the separation and analysis of chiral drugs mixture of isoprenaline hydrochloride and clorprenaline hydrochloride was established.A home made organic-inorganic hybrid open column was used as chromatographic separation column.The influences of separation and detection conditions including buffer concentration,pH value,operation voltage,separation temperature,sheath fluid type,sheath fluid additives and flow rate of the sheath fluid on resolution and ionization intensity were investigated.The results showed that the baseline separation of four components of two chiral drugs mixture were achieved within 18.5 min under the optimized conditions.关键词：capillary electrochromatography-electrospray-time of flight/mass spectrometry;isoprenaline hydrochloride;clorprenaline hydrochloride;chiral drugs mixture;chiral separation
- 1965
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- 1054
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发布时间： - 摘要：A stepwise regression method was introduced to study the relationship between cigarette sensory flavor and quality and organic acids in 25 cut tobacco samples.To identify organic acids key to sensory flavor and quality index,variable selection was performed for 15 measured organic acids.The regression models were applied in three trial productions of cigarette samples,and the predicted sensory flavor and quality scores were close to the true values,indicating that the selected organic acids variables in the models were well associated with the corresponding sensory flavors and quality indexes.All the results showed that organic acids in cut tobacco,such as isopentanoic acid,malonic acid,phenylacetic acid and citric acid,had either positive or negative effects on different sensory flavors and quality indexes.关键词：cigarette;sensory flavor and quality;organic acid;stepwise regression analysis
- 2042
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发布时间： - 摘要：An immunosensor for the sensitive and simple recognition of low concentrations of influenza viruses was constructed.Gold electrode was coated with H1 subtype-specific monoclonal antibodies to selectively capture the target virus.Horseradish peroxidase（HRP） as a catalyst to reduce hydrogen peroxide（H2O2） in the methylene blue（MB） solution was immobilized on the biosensor.The change of reduction peak current for specific recognition of antigen virus was monitored by square wave voltammetry（SWV）.The biosensor exhibited a fast amperometric response and a good stability to H2O2-MB system.The dynamic range for antigen recognition was in the range of 0.01-2.0 μg/mL with a detection limit（S/N=3） of 5.0 ng/mL.The results indicated that HRP had a good sensitivity and a simple operation for the detection of influenza virus.关键词：electrochemical immunoassay;influenza A（H1N1） virus;HRP
- 1944
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发布时间： - 摘要：The sample was extracted with 007 mol/L hydrochloric acid.Migratable chromium in the extract was determined by inductively coupled plasma mass spectrometry（ICP-MS）.Some other extract was taken and the high content of interferential positive ions was removed by co-precipitation method with aluminium nitrate.Then Cr（Ⅵ） in the extract was determined by ion chromatography-inductively coupled plasma mass spectrometry（IC-ICP-MS）.Cr（Ⅲ） content was obtained by minusing Cr（Ⅵ） content from the total migratable chromium content （Cr（Total））.The method quantitation limit for Cr（Total） and Cr（Ⅵ） reached to 0.01 mg/kg and 0.003 mg/kg,respectively.The method was then validated by conducting standard-addition experiments to the difference categories of toy materials according to Toy Safety Directive 2009/48/EC.The recoveries of Cr（Total） and Cr（Ⅵ） from the standard-addition experiments were in the ranges of 90.2%-101.5% and 96.7%-1067%,respectively, and the inter laboratory relative standard deviations were less than 7.4% and 7.9%,respectively.Therefore,the method was concluded to be accurate and reliable,which could satisfy the requirements of Cr（Ⅲ） and Cr（Ⅵ） in 3 categories of toy materials of Toy Safety Directive.关键词：toys;Cr（Ⅵ）;Cr（Ⅲ）;co precipitation;IC;ICP-MS;speciation analysis
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发布时间： - 摘要：A method was developed for the determination of benzo［α］ pyrene in Sarcandra galbra by solid phase extraction/high performance liquid chromatography（HPLC） with fluorescence detector.The benzo［α］ pyrene in Sarcandra galbra was extracted with n-hexane,and purified with neutral alumina column.The prepared samples were analyzed by HPLC with fluorescence detector at λex=370 nm and λem=425 nm,using acetonitrile-water（85∶15） as mobile phase at a flow rate of 1.0 mL/min.The results showed that a good linearity was achieved in the range of 0-20 ng/mL for benzo［α］ pyrene with a correlation coefficient of 0.999 9.The limit of quantitation（LOQ） was 0.36 μg/kg.The mean recoveries of benzo［α］ pyrene were in the range of 84.4%-101.9% with relative standard deviations（RSDs） of 1.6%-5.6%.The method is accurate,sensitive and repeatable,and is suitable for the analysis of benzo［α］ pyrene in traditional Chinese herbal medicines.关键词：benzo［α］ pyrene;Sarcandra galbra;solid phase extraction;high performance liquid chromatography/fluorimetric detection
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发布时间： - 摘要：Magnetic solid phase extraction is a kind of new sample pretreatment technique based on magnetic materials.It is currently a hot research in sample pretreatment field，and the study on magnetic adsorbent material is the key to this technique.The ionic liquids are a kind of liquid and organic salts composed of organic cations and organic or inorganic anions.Due to their low volatility，chemical and thermal stability，and good dissoluvability toward organics and inorganics，ionic liquids have been developed as a new adsorbent material for the preconcentration of organic pollutants and heavy metal ions in aqueous samples.However，the research on ionic liquids application in magnetic solid phase extraction is still in early stages.This paper summarizes the types of ionic liquids used in the magnetic enrichment techniques，and the present magnetic enrichment techniques based on ionic liquids into three categories，namely，the magnetic solid phase extraction based on ionic liquids functioned magnetic nanoparticles，the mixed hemimicelle magnetic solid phase extraction based on ionic liquids and the dual magnetic microextraction based on ionic liquids.The application of magnetic enrichment techniques based on ionic liquids in environmental，food and biological sample pretreatment are also reviewed.Subsequently，the principles that should be taken into consideration are briefly summarized when the magnetic enrichment techniques based on ionic liquids according to the analytes are selected.In the end，the future development direction of the magnetic enrichment techniques based on ionic liquids is outlooked.关键词：ionic liquids;magnetic solid phase extraction;pretreatment technique;environmental analysis;review
- 1965
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- 1161
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- 1
发布时间： - 摘要：The total concentration is important for the detection of malodorous substances.But what is more,the compositions and corresponding concentrations of malodorous substances are also necessary.With the development of analytical techniques for trace gas,more and more malodorous contaminants could be analyzed quantitatively.Due to a wide variety of species and properties,the analytical methods of malodorous substances are varied.This article is an overview on instrumental analysis methods for malodorous substances.The issues of sampling,pretreatment,and selection of analytical instruments are discussed according to the physical and chemical characteristics of different malodorous substances, and the analytical techniques and standards available are also summarized.关键词：malodorous compounds;pretreatment methods;instrumental analysis methods;analysis techniques and standards
- 2086
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- 4
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- 8
发布时间： - 摘要：As a class of green organic compounds,ionic liquids have some excellent properties,such as negligible vapor pressure,good solubility and thermal stability,high ionic conductivity and wide electrochemical stability window.Therefore,they have been widely applied in the fields of chemistry and chemical engineering,and nowadays have gained more and more attention.This paper reviewed the recent applications of ion chromatography in the analysis of ionic liquid anions and cations.Our discuss mainly focuses on three aspects of the application of ion chromatography,namely,the determination of ionic liquid cations by ion chromatography,the determination of ionic liquid anions by ion chromatography and the simultaneous determination of ionic liquid anions and cations by ion chromatography.This paper also prospects the development of the determination on ionic liquids by ion chromatography.关键词：ionic liquids;ion chromatography;anions and cations;review
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- 1334
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发布时间： - 摘要：Using selective reagents in the separation technique of complexation counter-current chromatography can improve the resolution effectively.The commonly used selective reagents include metal ion selective reagent,polysaccharideion selective reagent,anionic surface active agent,ion pair selective reagent,chiral reagent and acid-base reagents of pH-zone-refining.In this paper,the applications of different kinds of selective reagents in counter-current chromatography were summarized.The fundamental principle was introduced,and the way to improve the resolution was analyzed.Finally,the scope of application and the development trend of each selective reagents were also discussed.关键词：Counter-current chromatography;selective reagent;fundamental principle;review
- 2085
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- 1000
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- 0
发布时间： - 摘要：The sample preparation technique for nitrate and nitrite reference material in skim milk powder was studied and evaluated.A candidate reference material was prepared by matrix spiking and vacuum freeze drying method.The method of acetic acid protein precipitation-solid extraction/ion chromatography with ultra violet detector was used for the assessment of the prepared sample.Compared with the conductivity detector suggested by the national standard method,UV detector could be more efficient in avoiding the co-eluted constituent interference in milk matrix and enhancing detection precision,to meet the requirement for evaluation of preparation recovery,homogeneity and stability of the milk powder sample.The measured values of nitrite and nitrate in sample agreed with the target values of preparation,with recoveries of 91% and 101%,respectively.The assessed relative uncertainties obtained from the in-homogeneity of nitrite and nitrate by analysis of variance were 2.9% and 0.3%,respectively,with the minimum sample intake of 1.0 g.The short-term and long-term stabilities in -20 ℃,dry,vacuum and light-proof packaging conditions were predicted to be satisfactory by isochronous and accelerated stability study at -70,-20,4,20,35, 45 ℃,and linear regression trend analysis.The research demonstrated that it was feasible to develop the milk powder reference material containing nitrate and nitrite.The established sample preparation method could ensure the accuracy of reference materials characterization results.关键词：reference material;ion chromatography;nitrate;nitrite;milk powder
- 2024
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- 1163
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