最新刊期
卷 32 ， 期 4 ， 2013
- 摘要：A GC/ECD method for the simultaneous analysis of thiamethoxam,chlorfenapyr and lambda-cyhalothrin residues in tea and soil was developed and validated.The samples were extracted with acetonitrile after water soaking,and purified by QuEChERS method using PSA,GCB and Florisil as adsorbents,then determined by GC/ECD.The result showed that the calibration curves were linear in the ranges of 0.50-400 μg/L for thiamethoxam,0.20-100 μg/L for chlorfenapyr and 0.40-200 μg/L for lambda-cyhalothrin,with correlation coefficients more than 0.99.The limits of detection（LODs） for thiamethoxam,chlorfenapy and lambda-cyhalothrin were 0.25,0.05,0.10 μg/L,respectively.The average recoveries in tea and soil at three spiked levels were between 62% and 108% with RSDs（n=5）no more than 15.8%,and the limits of quantitation（LOQs） were lower than 10 μg/kg.This method is easy,quick,effective and safe,and can meet the requirements for simultaneous residue determination of thiamethoxam,chlorfenapyr and lambda-cyhalothrin in tea and soil samples.关键词：QuEChERS;GC/ECD;tea;soil;thiamethoxam;chlorfenapyr;lambda-cyhalothrin;residue analysis
- 3147
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- 1874
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- 26
发布时间： - 摘要：By virtue of high shear dispersing emulsification(HSDE) technology,the extraction of four kinds of polyphenols(e.g.(-) epigallocatechin gallate,(-) epigallocatechin,(-) epicatechin gallate,and (-) gallocatechin gallate),gallic acid and caffeine in the tea leaves was studied by using 20% ethanol aqueous solution as extraction solvent.The kinetics and thermodynamics of the extraction process were investigated.The kinetic equations in extraction process of the four kinds of polyphenols,gallic acid and caffeine were obtained according to kinetic theory,and the rate constant k was also calculated.The values of thermodynamic parameters such as enthalpy,entropy and free energy were computed based on thermodynamic theory.Furthermore,the extraction mechanism was explored on the basis of kinetic and thermodynamic analyses.The optimal conditions of the extraction method through HSDE technology were as follows:extraction solution:20% alcohol aqueous solution,solid-liquid ratio:1∶50,rotation speed:10 000 r/min,extraction time:180 s,extraction temperature:313.15 K.Under the optimum conditions,the extraction efficiencies of active ingredients in tea leaves could reach up to 95%.Compared with other pretreatment methods for tea leaves,the proposed method possesses many advantages such as higher extraction speed,less consumption of extraction solution and higher extraction efficiency.The method would have a good prospect in application of the extraction of natural product.关键词：high shear dispersing emulsification;kinetics;thermodynamics;tea leaves;polyphenols
- 2180
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- 1025
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- 1
发布时间： - 摘要：An internal standard quantitative method was developed for the simultaneous determination of 24 phthalate esters(PAEs) in sea foods by gas chromatography-mass spectrometry(GC-MS).1.0 g Sample was taken into glass centrifuge tube,followed by adding 100 μL internal standard solution(10 mg/L),0.5 g NaCl and 5 mL acetonitrile-acetate ester(1∶1) extraction solution.The solution was mixed for 1 min,and extracted by ultrasonic for 5 min and centrifuged for 5 min at 4 000 r/min.The extraction step was repeated with 3 mL acetonitrile-acetate ester.The two extracted solvents were concentrated to 1-2 mL,and then cleaned up through a glass Florisil SPE column.The analyses of 24 PAEs were carried out by GC-MS under selected ion monitoring(SIM) mode.The results showed that 24 PAEs had good linear relationships(r＞0.999) between 0.05 mg/L and 10.0 mg/L.The limits of quantitation(LOQs) of 24 PAEs were in the range of 1-500 μg/kg,and the limits of detection(LODs) were in the range of 0.1-100 μg/kg.The average recoveries of 24 PAEs in fish and prawn samples ranged from 73% to 120%,with relative standard deviations(RSDs,n=6) of 2.0%-19.7%.The method was well suitable for the determination of PAEs in sea foods with its high sensitivity and precision.关键词：sea foods;phthalate esters;SPE;gas chromatography-mass spectrometry(GC-MS)
- 2688
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- 1137
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- 8
发布时间： - 摘要：A uniform and stable inorganic-organic nanocomposite containing single-walled carbon nanotubes（SWNTs） and dodecyl aldehyde（DA） was obtained by ultrasonication method.The dispersant was dropped on a glassy carbon electrode surface for dryness to get a modified electrode（SWNTs-DA/GCE）.Then the amino modified single-stranded probe DNA was covalently immobilized on SWNTs-DA/GCE by a facile amine-aldehyde condensation reaction,from which a novel DNA electrochemical sensor was constructed.The layer by layer assembly process of the biosensor was characterized by cyclic voltammetry and electrochemical impedance spectroscopy using ［Fe（CN）6］3-/4- ions as electroactive probes.The analytical performance of the biosensor was investigated through using methylene blue（MB） as the hybridization indicator,and the results showed that the peak currents of MB on the biosensor had a good linear relationship with logarithm values of the target DNA concentrations（lgCS2） in the range of 1.0×10-15-1.0×10-10 mol/L(r=0.998）.Based on three times of the signal to noise ratio（S/N=3）,the limit of detection was estimated to be 2.0×10-16 mol/L.The selectivity experiments further showed that the complementary sequences,three base mismatched sequences and the non-complementary sequences could be well distinguished by the biosensor.关键词：SWNTs;dodecyl aldehyde;composite material;methylene blue;DNA sensor
- 1948
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- 1066
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- 2
发布时间： - 摘要：A high performance liquid chromatography-tandem mass spectrometric（HPLC-MS/MS） method was developed for the analysis of the absorbed components in serum after intragastric administration（i.g.） of Xianlinggubao（XLGB）,a kind of traditional Chinese medicine prescription,to rats.Methanol-acetonitrile（2∶1） was used for serum sample pretreatment.The separation of components was achieved on a C18 column by gradient elution with acetonitrile（containing 0.1% formic acid）-0.1% formic acid water solution as mobile phase.The ion acquisition was performed by full scan MS and MS/MS in positive ion mode.The serum after i.g.XLGB to rats,blank serum of rats and XLGB were analyzed by HPLC-MS/MS.13 prototype compounds were confirmed and 2 metabolites were identified in serum by comparing the retention time and mass spectrometry fragmentation characteristics with that of reference substance added in blank serum as well as literatures,which mainly derived from Herba Epimedii Brevicornus,Fructus Psoraleae,Radix Dipsaci and Rhizoma Anemarrhenae.It revealed that these four compositive herb medicines contribute more to the effect of XLGB.The analysis of the absorbed components of Xianlinggubao in serum after administration would provide an experimental basis for revealing the in vivo bioactive components of Xianlinggubao in anti-osteoporosis.关键词：Xianlinggubao;absorbed components in serum;HPLC-MS/MS;bioactive component of anti-osteoporosis;rat
- 2086
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- 936
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- 1
发布时间： - 摘要：The major parameters affecting the accurate and precise determination of lead isotopic ratios by multiple collectors inductively coupled plasma mass spectrometry(MC-ICP MS) were investigated.In the optimized conditions,the relative standard deviations(RSDs) of lead isotopic ratios for NIST SRM 981 standard solution by thirty repeated determinations in 10 h at lead concentration of 4 ng/mL were about 0.005% for 208Pb/206Pb,0.004% for 207Pb/206Pb and 0.054% for 206Pb/204Pb,respectively.Long term stability was tested and the standard deviations(2SD) of 208Pb/206Pb,207Pb/206Pb and 206Pb/204Pb were 0.000 06,0.000 05 and 0.006 7,respectively.A method of NEPTUNE MC-ICP MS for the analysis of stable lead isotopic ratios in trace lead marine carbonates was developed.Hainan corals(Porites lutea) and giant clams(Tridacna gigas) were analysed,the procedural blank of 8-10 pg and the errors of repeated samples better than 0.1% were obtained.After eluted with 0.50 mol/L HNO3,208Pb/206Pb and 207Pb/206Pb in Hainan corals were determined to be 2.086 2 ± 0.001 5 and 0.849 90 ± 0.001 47(n=16),respectively,and 208Pb/206Pb and 207Pb/206Pb in Hainan giant clams were 2.116 9 ± 0.004 2 and 0.864 81 ± 0.001 62(n=9),respectively.The 204Pb ratios of marine carbonates in South China Sea were also reported.The results showed that the lead isotopic ratios of marine carbonates in South China Sea were related to Chinese aerosols,atmospheric deposits of Pearl River Delta,loess,basalts from the South China Sea,etc.The method could be applied in the determination of lead isotopic ratios in marine carbonates that have low lead concentration but complicated matrix with high calcium concentration.关键词：multiple collectors inductively coupled plasma mass spectrometry;marine carbonate;lead isotopic ratio
- 2958
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- 1296
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- 1
发布时间： - 摘要：The fragment ions of rhein in total ions mass chromatogram and collision inductive dissociation multi-level mass were studied by electrospray ionization ion trap mass spectrometry(ESI-IT MS).Quantum chemistry calculations were carried out to explore the mass behavior of rhein and the main fragment ions from the molecule.By analysing the characteristic of the fragment ions including geometry parameter,bond dissociation energy,changes of charge,spin density and frontier molecular orbital,the stable structures of the fragment ions with m/z 282.8,256.9,238.9,210.8,192.8,182.8,166.8,and fragmentation pathways could be obtained,the cracking behavior of rhein could be explained systematically by ESI-IT MS.关键词：rhein;electrospray ionization ion trap mass spectrometry(ESI-IT-MS);quantum chemistry
- 45411
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- 2705
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- 3
发布时间： - 摘要：Organophosphate esters(OPs) are widely used as flame retardants and plasticizers.A rapid method for the determination of seven OPs in water was developed based on enrichment via solid-phase extraction(SPE) and determination by gas chromatography-mass spectrometry(GC-MS).The SPE cartridge and elution solvent were optimized,consequently,Oasis HLB(200 mg) cartridge was chose as extractive cartridge and ethyl acetate was selected as elution solvent.Under the optimized conditions,the developed method was verified using the blank spiked and the matrix spiked,and acceptable recoveries and good reproducibilities were achieved,with recoveries of(74±12)%-(118±3.0)% and(62±6.9)%-(121±2.2)% for the blank spiked and the matrix spiked,respectively.The instrumental detection limits(IDLs) for specific chemicals were in the range of 4-15 μg/L.The established method was proved to be efficient via measurement on the occurrence and concentrations of the 7 OPs in two surface water samples collected from the Pearl River,and effluent from a waste water treatment plant (WWTP) in Guangzhou.关键词：organophosphate esters;flame retardant;plasticizer;solid phase extraction;GC-MS
- 2327
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- 3964
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- 15
发布时间： - 摘要：A systematic method for the estimation of stability of valtrate was established.HPLC-electrospray tandem mass spectrometry(HPLC-ESI MS/MS) was applied to separate the degradation products of valtrate and identify structures of the main degradation products.The samples were separated on an Agilent Extend-C18 by gradient elution using acetonitrile-0.25% acetic acid as mobile phase and analyzed under positive ion mode.Four degradation products were identified with the parent nucleus structures of baldrinals-compounds,in which one of oxidation products was identified through the reference substance.An HPLC method was established for the determination of the content change of valtrate in H2O2 at different time points.The result indicated that the content change of valtrate in H2O2 fits the first order kinetic equation，and the degradation of 10% prototype product occurred in 0.5 h.This paper revealed the degradation mechanism and degradation rule of valtrate from two aspects of both qualitative and quantitative analysis,and provided a theoretical basis for further research.关键词：HPLC-ESI MS/MS;valtrate;oxidation kinetics;stability
- 2399
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- 1015
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- 0
发布时间： - 摘要：A simple and rapid method was developed for the simultaneous determination of 8 prohibited drugs，including minoxidil,estriol,spironolactone,canrenone,estrone,estradiol,diethylstibestrol and progesterone,in hair growth cosmetics.The sample was extracted by methanol and then purified by an HLB solid phase extraction cartridge.The extraction residue was redissolved in methanol and separated on an Agilent Poroshell 120 Bonus-RP chromatographic column by gradient elution using 10 mmol/L ammonium acetate-methanol as mobile phase.The simultaneous qualitative and quantitative analysis of 8 prohibited drugs were performed by high performance liquid chromatography-diode array detection(HPLC/DAD).Under the optimized conditions,the calibration curves of 8 drugs were linear in the range of 0.5-100 mg/L.The average recoveries of 8 drugs at three spiked levels of 5.0,10.0,50.0 mg/kg were between 80% and 96%,with relative standard deviations of 3.7%-8.9%.The quantitation limits(S/N=10) of spironolactone and progesterone were 2.0 mg/kg,and those of the rest drugs were 5.0 mg/kg.The method was simple,rapid and accurate,and could meet the requirement for the determination of 8 prohibited drugs in hair growth cosmetics.关键词：hair growth cosmetics;prohibited drugs;high performance liquid chromatography(HPLC);diode array detection(DAD);rapid determination
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- 6
发布时间： - 摘要：A reversed-phase high performance liquid chromatography coupled with UV detection(RP-HPLC/UV) was developed and validated for the simultaneous determination of four isoflavonoids，including puerarin(PU),3-methoxy puerarin(MP),mirificin(MI) and daidzin(DA),in the bioactive fraction of Naodesheng prescription,ie.a widely used herbal medicine(HM) in China mainly for treatment of cerebral arteriosclerosis,ischemic stroke,sequelae of cerebral hemorrhage and etc.The separation of four compounds was accomplished on a Hyspersil ODS-2 column(250 mm×4.6 mm,5 μm i.d.) by using methanol-water(25∶75) as mobile phase with isocratic elution at a flow rate of 0.9 mL/min.The UV detection wavelength was set at 250 nm,and the column temperature was 25 ℃.The high resolution and reproducible peaks were achieved for four compounds in 20 min.All the calibration curves showed good linearities(r≥0.999 7) over the test concentration range.The relative standard deviations(RSDs) of the method were less than 2.2% for precision,stability and reproducibility assays,and the spiked recoveries were in the range of 96%-102%.The total contents of the four isoflavonoids were determined to be in the range of 37.3%-37.8%in the bioactive fraction of Naodesheng prescription.关键词：Naodesheng prescription;bioactive fraction;high performance liquid chromatography(HPLC);isoflavonoid;determination
- 2095
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- 1143
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- 2
发布时间： - 摘要：A high performance liquid chromatographic(HPLC) method for the separation of florfenicol enantiomers using a Chiralpak AD-H(4.6 μm×250 mm，5 μm) was established.The influences of the base additive,the kinds and concentrations of alcohol additives on the chiral separation of florfenicol including resolution,retention time,theoretical plate and tailing factor were investigated.The results indicated that florfenicol was separated well from its optical isomer with n-hexane∶isopropyl alcohol∶methanol(70∶15∶15) as mobile phase at a flow rate of 1 mL?min-1 and a column temperature of 30 ℃. The UV detection wavelength was set at 224 nm.The calibration curve for florfenicol was linear in the concentration range of 0.05-0.5 g?L-1 with correlation coefficient of 0.999 7.The limit of detection(LOD) was 0.1 μg?L-1.The intra-day relative standard deviations(RSD) were less than 1.8% and the inter-day RSDs were less than 2.3%.The average spiked recoveries were in the range of 109%- 112% with RSDs not more than 3.0%.The method was reliable and simple,and was suitable for the quality control of florfenicol in industrial production.关键词：florfenicol enantiomers;high performance liquid chromatography(HPLC);chiral separation;optical purity
- 2264
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- 1141
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- 3
发布时间： - 摘要：A carbon nanotube(CNT) thin film field emission cathode was prepared by drop casting method,and its field emission characterisitic was studied by ultra violet photoelectron emission spectroscopy and Raman spectroscopy.The results indicated that the field emission curves of the CNT thin films obeyed the Fowler-Nordheim(FN) theory.The minimum turn-on field and the threshold field were 3.33 MV/m and 5.44 MV/m,respectively.The field enhancement factor was found to be around 103.The ultraviolet photoelectron emission spectral analysis showed that the low-energy cut-off edge of the CNTs thin film gradually decreases as the applied bias increases,which indicated that the applied bias has pull down the effective emission barrier greatly so that electrons can emit at smaller electrical field without geometric enhancement.The reduction of effective emission barrier is explained by the contact effect from the CNTs/Ni interface.In addition,the bias drop on the thin film also leads to the reduction of the surface barrier,which is particularly obvious in the unpurified CNTs thin film,and it is related to the residue of amorphous carbon(a-C) in the thin film.关键词：carbon nanotube thin film;field electron emission;photoelectron emission spectroscopy
- 1984
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- 967
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- 0
发布时间： - 摘要：Bidentate ligand HL was prepared by two steps from the cheap commercial available 8-hydroxyquinoline and characterized by ESI-MS,NMR and elemental analysis methods.Mononuclear complex 1 was readily obtained in good yields by heating Co(NO3)2 and HL in solution.It belongs to monoclinic system with space group P2/c,a=10.967(7) ?,b= 8.639(5) ?,c=18.087(11) ?;V=1 656.0(17) ? 3,Z=4,Dc=1.541 mg/m3,R1=0.032 0,wR2=0.078 4.The cobalt atom found in the mononuclear unit is pentacoordinate,and adopts a distorted trigonal-bipyramidal geometry,and coordinates to four atoms N2O2 of two ligands and one pyridine N atom.The PXRD experiment showed that the crystal structure of complex 1 was truly representative of their bulk materials.From TGA results,the mononuclear complex was found to have a thermal stability.关键词：8-hydroxyquinoline;synthesis;characterization;crystal structure
- 2335
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- 1074
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- 0
发布时间： - 摘要：A microchip capillary electrophoresis with contactless conductivity detection method was developed for the rapid determination of glucose and sodium chloride in the injection preparation.The pH value and constituent of running buffer were investigated to gain the effective resolution of the two ingredients.The excitation frequency of the detector was also surveyed in view of the signal response and detection sensitivity.The optimal conditions were as follows:separation media:20 mmmol/L borate（pH 9.6）,separation voltage:1 200 V,excitation frequency:70 kHz.Under the optimal conditions,the two analytes could be successfully separated within 60 s.Good linearities（r≥0.992） for NaCl and glucose were obtained in the ranges of 20-1 000 μmol/L and 50-5 000 μmol/L,respectively.The limits of detection（S/N=3∶1） were 8.2 μmol/L and 26.7 μmol/L,respectively.The spiked recoveries for Na+ and glucose were 95%-99% and 97%-104%,respectively,with relative standard deviations（RSDs,n=3） less than 4.0%.The present work provided an approach of choice to the simultaneous quantitative analysis of glucose and NaCl in the compound preparation widely used in clinical therapeutics.With the advantages of convenience,rapidity,considerable accuracy and stability,this method was applied in the determination of Na+ and glucose in real sample with satisfactory result.关键词：capillary electrophoresis;contactless conductivity detection;glucose;sodium chloride;assay
- 1989
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- 1021
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- 2
发布时间： - 摘要：An immunoaffinity column purification and high performance liquid chromatographic（IAC/HPLC） method was established for the simultaneous determination of 16 sulfonamide(SAs) residues in animal-originatal food products.The samples were extracted with 80% ethanol,cleaned-up with an immunoaffinity column,and analyzed by HPLC.The separation of 16 SAs was performed on an Agilent Eclipse XDB-C18 column using methanol(A)-pH 3.5 phosphate buffer(B) as mobile phase by gradient elution at a flow rate of 1.0 mL/min.The detection wavelength was set at 270 nm.The injection volume was 50 μL.All of 16 SAs residues were simultaneously separated and determined by HPLC within 42 min.Linear ranges of 16 SAs were in the range of 10-200 μg/L with correlation coefficients more than 0.999.The average recoveries at spiked concentration levels of 20,50 and 100 μg/kg ranged from 62% to 104%,with relative standard deviations(RSDs) of 0.9%-6.6%.The detection limits(S/N=3) ranged from 4 μg/kg to 10 μg/kg.The method was suitable for the determination of sulfonamide residues in the edible animal products,with advantages of simplicity，rapidness，sensitivity and environment friendliness.关键词：sulfonamides(SAs);immunoaffinity column;high performance liquid chromatography
- 2204
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- 1251
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- 6
发布时间： - 摘要：A high-performance liquid chromatography tandem mass spectrometric(LC-MS/MS) method was developed for the determination of histamine in the supernatant after degranulation of P815 cells．After pretreatment procedure,the sample was separated on a C18(4.6 mm × 100 mm，3.5 μm) column using acetonitrile-0.5 mmol/L ammonium acetate solution with 0.3% formic acid(60∶40) as mobile phase at a flow rate of 0.4 mL/min.The target compound was detected by positive ion ionization mass spectrometry(ESI MS) under multiple reaction monitoring(MRM) mode using m/z 112＞95 and m/z 112＞68 as detection ion.Under the optimal conditions,the analysis of sample could be completed within 6 min.A good linear relationship was obtained for histamine in the range of 4.0-128.0 μg/L with a correlation coefficient(r2) of 0.997 9.The limit of quantitation(S/N＞10) and limit of detection(S/N=3) were 1.2 μg/L and 0.3 μg/L,respectively.The mean recoveries for histamine in the supernatant of cells at three spiked concentration levels of 16,64,128 μg/L were in the range of 90%-94% with relative standard deviations(RSDs,n=6) of 4.1%-5.9%.The proposed method was simple,sensitive and reproducible,and was suitable for the determination of histamin in the supernatant of Traditional Chinese Medicine Injection(TCMI) on degranulation in P815 cells.关键词：histamine;LC-MS/MS;Traditional Chinese Medicine Injection(TCMI);P815 cells
- 1905
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- 943
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- 0
发布时间： - 摘要：The molecular structure of 5-［2-propoxy-5-（3,5-dimethylpiperazin-1-yl-sulfonyl）phenyl］-1- methyl-3- n-propyl-1,6-dihydro-7H-pyrazol［4,3-d］pyrimidin-7-one was elucidated by 1D NMR（1H,13C NMR） and 2D NMR techniques，including gradient homonuclear correlation spectroscopy（1H-1H COSY）,gradient heteronuclear single-quantum coherence（HSQC） and gradient heteronuclear multiple-bone coherence（HMBC）,together with the infrared spectral analysis and elementary analysis.The 1H NMR and 13C NMR signals for 5-［2- propoxy-5-（3,5- dimethyl- piperazin-1- yl-sulfonyl）phenyl-1-methyl-3-n-propyl-1,6-dihydro-7H-pyrazol［4,3-d］pyrimidine-7-one were assigned.The data obtained could be used to detect sildenafil analogues.关键词：1D NMR;2D NMR;assignment;qualitative analysis
- 2802
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- 1304
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- 7
发布时间： - 摘要：The electrochemical behavior and reaction mechanism of scutellarin on the graphite electrode were investigated by cyclic voltammetric method on graphite electrode.A couple of sensitive and quasi-reversible redox peaks were obtained,with an oxidation peak at 0.154 V and a reduction peak at 0.073 V.The voltammetric behavior of scutellarin in different pH values showed that its oxidation reaction on the electrode involved two electrons and two prontons.The voltammetric behavior of scutellarin at different scan rates showed that its oxidation process was an adsorption-controlled process at low scan rates and a diffusion-controlled process at high scan rates.In 0.1 mol/L phosphate buffers（pH 7.0）,the oxidation peak current of scutellarin in differential pulse voltammetric（DPV） curve was proportional to the concentration range of 5.0×10-7-5.0×10-5 mol/L with a detection limit of 1.5×10-7 mol/L.This method was applied in the determination of scutellarin in Erigeron breviscapus with recovery of 98%.关键词：scutellarin;electrochemical behavior;graphite electrode;differential pulse voltammetry
- 2062
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- 913
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- 1
发布时间： - 摘要：A solid phase extraction coupled with high performance liquid chromatographic（SPE/HPLC） method was developed for the determination of nine halophenols,e.g.2,6-dichlorophenol,2,3-dichlorophenol,2,5-dichlorophenol,2,4-dichlorophenol,3,4-dichlorophenol,3,5-dichlorophenol,2,4,6-trichlorophenol,pentachlorophenol and bithionol,in cosmetics.The samples were dispersed with saturated sodium chloride solution,extracted with acetonitrile under ultrasonication,and cleaned up with HLB solid phase extraction.The separation of nine halophenols was carried out on a C8 column using methanol-acetonitrile-ammonium acetate buffer as mobile phase.The result indicated that the calibration curves of nine halophenols were linear between 1.0 mg/L and 50.0 mg/L,with correlation coefficients more than 0.999.The limits of detection were in the range of 0.3-0.6 mg/kg.The mean recoveries of nine halophenols at spiked levels of 2.0,4.0,20.0 mg/kg were in the range of 92%-105% ,with RSDs（n=6） of 0.89%-3.1%.The method was sensitive,reproducible and accurate.关键词：high performance liquid chromatography（HPLC）;solid phase extraction（SPE）;cosmetics;halophenols;determination
- 2627
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- 1186
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- 6
发布时间： - 摘要：A GC-MS method was developed for the simultaneous determination of 2-hydroxybiphenyl and 7 chlorophenols in leathers.The crushed leather sample was extracted with methanol in ultrasonic bath,then evaporated and concentrated,and then acetylated with acetic anhydride and extracted with n-hexane.After concentrated and set the volume,the target compounds were analyzed by GC-MS and quantified by the external method.The results indicated that the calibration curves were linear in the range of 0.02-0.30 mg/L,with correlation coefficients of 0.998 9-0.999 9.The mean recoveries of 2-hydroxybiphenyl and 7 chlorophenols in the blank sample were in the range of 89%-106%，with relative standard deviations(RSDs,n=7) of 1.8%-8.8%.The quantitation limit of the method was lower than 0.01 mg/L.The method was simple,efficient,accurate and sensitive,and could meet the needs of a variety of phenols substances detection in the import and export of leather and leather products.关键词：leather;2-hydroxybiphenyl;chlorophenol;GC-MS;determination
- 2537
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- 1368
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- 10
发布时间： - 摘要：The effect of column temperature on the retention behavior of organic acids(aliphatic carboxylic acids and benzenecarboxylic acids) in ion exclusion chromatography with direct conductivity detection was investigated.Chromatographic separations of organic acids were performed on a Shim-pack SCR-102H ion-exclusion column using p-toluenesulfonic acid or sulfuric acid as mobile phase with a flow rate of 1.2 mL/min at various column temperatures from 25 ℃ to 50 ℃.The separations of six common aliphatic carboxylic acids(formic acid,acetic acid,propionic acid,butyric acid,valeric acid and caproic acid)were performed using 0.2 mmol/L p-toluenesulfonic acid as mobile phase.Six kinds of benzenecarboxylic acids(o-phthalic acid,salicylic acid,benzene acetic acid,p-hydroxybenzoic acid,benzoic acid,o-methylbenzoic acid) were eluted and separated using 0.08 mmol/L sulfuric acid as mobile phase.The results indicated that the retention values of organic acids were decreased with the increase of column temperature.However,for each organic acid,the effect degree of temperature is different.That is to say,the variations of retention values for each organic acid are different with the change of temperature.In general,the variations of retention values for strongly retained organic acids are greater than that for weakly retained species.Through the linear regression data,the conclusion that the linearities of the Van’t Hoff plots for organic acids are satisfactory may be derived.By changing the column temperature,the retention value variations of organic acids(especially the strong retain organic acids) can be realized,the peak shapes and separations of organic acids can be improved.关键词：Ion-exclusion chromatography;organic acids;temperature;conductivity detection
- 3262
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- 1096
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- 3
发布时间： - 摘要：Reference materials are helpful to the evaluation of the performance of laboratories and for the quality control of analytical procedures.However,reference materials containing veterinary drugs in royal jelly powder are not available.A method regarding the preparation of reference material for metronidazole residue in royal jelly powder was presented.About 400 packages of royal jelly powder were obtained from the non-compliant sample by the procedure of homogenation,cryodesiccation and packaging.The homogeneity,short-term stability and long-term stability were examined by F-test or t-test,and all of them could meet the requirement for reference material at a confidence level of 95%.The value of metronidazole in this sample was certified through the collaborative analysis program by 8 expert laboratories at home and abroad using different sample preparation procedures,but exclusively LC-MS/MS method.The data were evaluated by Grubbs test and Cochran test.Meanwhile,the uncertainty due to sample homogeneity,short-term and long-term stabilities and variabilities in the characterization procedure was estimated.关键词：royal jelly powder;metronidazole;reference materials;homogeneity;stability;certification
- 2234
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