气相色谱法测定纸包装中6种抗氧化剂的不确定度评定

目的:评定气相色谱法测定纸包装中6种抗氧化剂含量的不确定度。方法:依据SN/T 3043-2011采用气相色谱法对纸包装中6种抗氧化剂含量进行测定,通过分析不确定度的来源,建立评估的数学模型,计算不确定度的各主要分量,给出纸包装中6种抗氧化剂测定结果的扩展不确定度。结论:气相色谱法测定纸包装中6种抗氧化剂含量的测量不确定度的主要影响因素为标准系列溶液配制、标准曲线拟合、加标回收率。可通过选择精度更高的容量瓶与移液器、选择适当的浓度点制作标准曲线等措施降低检测结果的测量不确定度,进一步提高检测数据的准确度。

Classification of Chinese Traditional Drug-"Beimu" (Bulbus Fritillariae) by Pyrolysis High Resolution Gas Chromatography-Pattern Recognition

The combination of pyrolysis high resolution gas chromatography and pat- tern recognition techniques is a powerful tool for the classification of traditional Chinese drug.A study has been completed on 55 Beimu samples of five different geographic origins: Eastern China.Central China.South-western China,North-western China and North-eastern China.Principal component analysis and SIMCA are applied to effectively classifying the samples according to the origin of the plants.The chemical information contained in the high resolution gas chromatographic data is sufficient to characterize the geographic origin of sam- pies.

Study on Detection of Organochlorine Pesticide Residue in Ginseng

To investigate the residue situation of pesticides in ginseng, total 17 samples of ginseng-growing soil, ginseng roots and ginseng seeds were collected from 5 regions of Fusong County, and the contents of organochlorine pesticide residues in the samples were detected by using ultrasonic-assisted extraction and gas chromatography with acetone-ligroin as the solvent, thereby providing suitable recommendations and scientific basis for the selection of ginseng-growing soil.

奇蒿中挥发油的分析

报道了用气相色谱－质谱法对奇蒿挥发油进行分离和鉴定。共分离出６０余种化合物。

Analysis of Active Components of Hexane Extractives of Morus alba Leaves

[Objective]The aim was to explore the active compound of Morus alba leaves with the analysis of active components of hexane extractives of M.alba leaves.[Method]Antibacterial assays of hexane extractives of M.alba leaves were done and the volatile components of hexane extractives of M.alba leaves with the strongest antibacterial activity were analyzed by gas chromatography-mass spectrometry（GC-MS）.[Result]The results of inhibitory effect of hexane extractives of M.alba leaves on Staphylococcus aureus and Escherichia coli showed that hexane extractives of M.alba leaves collected in June,July and August had antibacterial activity against S.aureus and had no antibacterial effect against E.coli.Furthermore,hexane extractives of M.alba leaves collected in June had the strongest antibacterial activity against S.aureus（inhibition diameter 10.95 mm）.The hexane extractives of M.alba leaves collected in June was analyzed by GC-MS,the main volatile components were tetradecane（16.76%）,dodecane（13.20%）,diisobutyl phthalate（10.26%）,decane（9.10%）,hexadecane（8.71%）,linolenyl alcohol（7.25%）,octadecane（5.88%）,eicosane（3.26%）,dibutyl phthalate（2.59%）.[Conclusion]Linolenyl alcohol was the potential antibacterial compound.

Cellulase Extraction and Gas Chromatography Detection Technology of Swainsonine from Astragalus strictusin in Tibet

Locoweed is a poisonous plant wildly distributed in most areas of the world,which causes livestock poisoning or death with serious economic loss.The Astragalus strictus belongs to a species of Iocoweed.It is mainly distributed in Tibet of China and is a serious hazard to the local livestock industry.The objective of this study is extracting and purifying condition of Swainsonine from Astragalus strictus with the cellulase extraction method.An optimum extracting technology of SW from Astragalus strictus was investigated through the orthogonal experiment under the cellulose assistance conditions,and then the content of swainsonine was analyzed with gas chromatography （GC） method.The optimized extraction conditions were as follow：The crushed mesh is 40; solid-liquid ratio is 1∶40 （g/ml）; enzyme dosage is 3.5％; enzymatic time is 3 h.Under the above conditions,the extraction percentage of the swainsonine was 0.003 941％.The conditions for extracting swainsonine with cellulase extraction method are mild,it is easy to utilize industrial production.It is benefit for producing swainsonine from Astragalus strictus.

Analysis of Volatile Constituents in Bamboo Leaves Using HS-GC/MS

[Objective] This study aimed to analyze the volatile constituents in bamboo leaves. [Method] The volatile compositions in bamboo leaves were analyzed by headspace-gas chromatography-mass spectrometry （HS-GC/MS）, and identified by searching their mass spectra in NIST database. The relative percentages of them were calculated by the GC peak areas. [Result] Fifty-three chemical constituents in bamboo leaves were separated. Among them, the main components were alcohols, ketones and aldehydes, and these compounds contained unsaturated bonds. [Con- clusion] HS-GC/MS was simple and less sample-demanding and can be used for rapid analysis of volatile constituents in bamboo leaves and provide scientific basis for further research and development of bamboo leaves.

Investigation on Two Novel Substituted β-Cyclodextrins Used as GC Stationary

Aim To study the chromatographic behaviors of two dipentyl cyclodextrin derivative stationary phases. Methods Two new β-cyclodextrin derivatives, heptakis-[2, 6-di-O-pentyl-3-O-(4-nitrobenzyl)] -β-CD and heptakis-[2, 6-di-O-pentyl-3 -O-(5 -hexenyl)]-β-CD, were synthesized and coatal on fed-silica capillary columns. The chromatographic behaviors of the columns were characterized . Results It was found that the she, polarity, and aromatic property of the substituted group at the 3-position of heptakis-(2, 6 - di - O - pentyl) - β - cyclodextrins greatly influenced their chromatographic properties and separation ability. The introduction of aromatic group or a group containing a double-bond may bring π-π interactions between the host and guest molecules, and therefore increases the separation ability of the β-CDs for substituted benzene isomers. Conclusion The new substituted β-CD compounds are very suitable for being used as gas chromatogaphic stationary phases.

Determination of constituents of essential oil from Angelica sinensis by gas chromatographymass spectrometry

Gas chromatographymass spectrometry (GC-MS) coupled with chemometric resolution upon two- dimensional data was employed to analyze the constituents of essential oils of Angelica sinensis. Constituents in essential oils of Angelica sinensis root were identified by GC-MS with the help of subwindow factor analysis (SFA) method resolving two-dimensional original data into mass spectra and chromatograms. 76 of 97 separated constituents in essential oil of Angelica sinensis root were identified and quantified, and they account for about 91.36% of the total content. The results show that ligustilide, butylene phthalide, 2-methoxy-4-vinylphenol, carvacrol, allo-ocimene,2,6,6-trimethylbicyclo-[3,1,1]hept-2-ene are the main constituents in essential oil of Angelica sinensis root.

Degradation of lignite model compounds by the action of white rot fungi

Three compounds modeled on the lignite structure were chosen for experimental degradation by different fungi strains. Culture conditions and extracellular enzyme activities were optimized. The growth curves of the strains were determined to study mycelium dry weight and protein content changes. Gas chromatography and infrared spectroscopy were used to detect changes of functional groups before and after the action of the fungi on the model compounds. Possible decomposition products and degrada-tion mechanisms were proposed. The research findings show that C. Versicolor and Golden Mushroom can grow in presence of the model compounds. The optimum culture conditions were a pH of 6.0, a carbon-nitrogen ratio of five and a Tween-80 concentration of 0.1%. Newly produced substances were found by gas chromatography. Infrared analysis showed that the model compounds degraded under the action of the microorganisms.

Potential therapeutic significance of increased expression of aryl hydrocarbon receptor in human gastric cancer

AIM： To determine the functional significance of aryl hydrocarbon receptor （AhR） in gastric carcinogenesis, and to explore the possible role of AhR in gastric cancer （GC） treatment. METHODS： RT-PCR, real-time PCR, and Western blotting were performed to detect AhR expression in 39 GC tissues and five GC cell lines. AhR protein was detected by immunohistochemistry （IHC） in 290 samples： 30 chronic superficial gastritis （CSG）, 30 chronic atrophic gastritis （CAG）, 30 intestinal metapiasia （IN）, 30 atypical hyperplasia （AH）, and 70 GC. The AhR agonist tetrachlorodibenzo-para-dioxin （TCDD） was used to treat AGS cells. MTr assay and flow cytometric analysis were performed to measure the viability, cell cycle and apoptosis of AGS cells.RESULTS： AhR expression was significantly increased in GC tissues and GC cell lines. IHC results indicated that the levels of AhR expression gradually increased, with the lowest levels in CSG, followed by CAG, IM, AH and GC. AhR expression and nuclear translocation were significantly higher in GC than in precancerous tissues. TCDD inhibited proliferation of AGS cells via induction of growth arrest at the G1-S phase. CONCLUSION： AhR plays an important role in gastric carcinogenesis. AhR may be a potential therapeutic target for GC treatment.

Measurement of Infinite Diluted Activity Coefficient of Solvents in Polymer by Inverse Gas Chromatography Method

The infinite diluted activity coefficients of solvents in polyisopropyl methylacrylate was measured using inverse gas chromatography. The solvents used were benzene, toluene, ethyl benzene, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methanol, ethanol isopropyl alcohol, butyl alcohol, 1,2-dichloroethane, and chloroform. It was observed that the infinite diluted activity coefficient of alcohols are well above those of the other solvents investigated.

Carbothermic reduction of alumina with carbon in vacuum

Carbothermic reduction alumina in vacuum was conducted, and the products were analysed by means of XRD and gas chromatography. Thermodynamic analysis shows that in vacuum the initial carbothermic reduction reaction temperature reduces compared with that under normal pressure, and the preferential order of products is Al404C, Al4C3, Al2OC, Al20 and A1. Experiment results show that the carbothermic reduction products of alumina are A1404C and A14C3, and neither A12OC, Al20 or Al was found. During the carbothermic reduction process, the reaction rate of Al203 and carbon decreases gradually with increasing time. Meanwhile, lower system pressure or higher temperature is beneficial to the carbothermic reduction of alumina process. A1404C is firstly formed in the carbothermic reaction, and then A14C3 is formed in lower system pressure or at higher temperature.

Spectroscopic Analysis of Structural Transformation in Biodiesel Oxidation

The oxidation behavior of three biodiesels of different origins,viz.rapeseed oil derived biodiesel,soybean oil derived biodiesel and waste oil based biodiesel,were tested on an oxidation tester.The chemical compositions of the biodiesels were characterized by gas chromatography.Thereafter,the structural transformation of fatty acid methyl ester(FAME)of the biodiesels was analyzed by an infrared spectrometer and an ultraviolet absorption spectrometer.The results demonstrated that the oxidation behavior of biodiesels of different origins was closely related to the composition and distribution of FAMEs.Higher concentration of unsaturated FAME with multi-double bonds exhibited poorer oxidation resistance.Furthermore,cis-trans isomerization transformation occurred in the unsaturated FAME molecules and conjugated double-bond produced during the oxidation process of biodiesel.Greater cis-trans variations corresponded to deeper oxidation degree.The higher the content of unsaturated FAME with multi-double bonds in a biodiesel,the more the conjugated double bonds was formed.

Chemical Composition of Essential Oil from Chimonanthus praecox Flower

Objective] To analyze the aroma constituents of essential oils from Chi-monanthus praecox. [Method] Extracted by microwave-assisted hydrodistil ation （MAHD）, aroma constituents of essential oils of Chimonanthus praecox flowers were analyzed by gas chromatography-mass spectrometry （GC-MS）. Normalization method was used to determine the constituents quantitatively. [Result] Total y 27 compounds were identified, accounting for 98.85% of total amounts. The main aroma con-stituents are terpenes, aldehydes, esters, alcohols and hydrocarbons. Main compo-nents with relative percentage over 5% are germacrene D （25.62%）, bornyl acetate （16.71%）, caryophyl ene （10.51%）, cis-α-ocimene （5.18%）, γ-elemene （8.05%）, β-linalool （5.01%）, 1-ethenyl-1-methyl-2,4-bis （1-methylethenyl）-cyclohexane （7.18%） and 2,3,4,4α,5,6-hexahydro-1,4αdimethyl-7-（1-methylethyl）-naphthalene （5.20%）. [Conclu-sion] The study provided a theoretical reference for the development and utilization of Chimonanthus praecox resources.

Determination of the gas compositions for direct coal liquefaction by gas chromatography

Via multi-dimensional gas chromatography, configured with parallel dual-channel, double detectors, valves switching and back flushing, rapid analysis of the gas compositions consisting of C1-C5 hydrocarbons and permanent gases, such as CO2, H2S, H2, and CO, for direct coal liquefaction has been realized. With four packed chromatographic columns, which are Hayesep-Q pre-column, Hayesep-Q column, molecular sieve 5A column and one PLOT A1203 S capillary column, the gas compositions for direct coal liquefaction are analyzed qualitatively and quantitatively by the external standard method. The determination method has such advantages as excellent separation, simple operation, rapid analysis and accurate results.

Uncertainty Evaluation for the Determination of Dibutyl Phthalate(DBP) Concentration in Liqueur by GC-MS

The dibutyl phthalate （DBP） concentration in liqueur was measured by gas chromatography-mass spectrometry （GC-MS）, and the uncertainty during the mea-surement was evaluated in this study. The results showed that the combined stan-dard uncertainty was determined as 0.028 and the expanded uncertainty was 0.056 at confidence probability p=95%, coverage factor k=2, by fol owing the methods de-scribed in GB/T 21911-2008 ＂Determination of Phthalate Esters in Foods＂. The av-erage DBP concentration in the liqueur of eight repeated measurements was（0.985＆#177; 0.056） mg/kg finaly.

Ethanol-Water Near-Azeotropic Mixture Dehydration by Compound Starch-Based Adsorbent

Ethanol-water near-azeotropic mixture dehydration was investigated by formulated compound starchbased adsorbent(CSA), which consists of corn, sweet potato and foaming agent. The net retention time and separation factor of water over ethanol were measured by inverse gas chromatography(IGC). Results indicated that water has a longer net retention time than ethanol and that low temperature is beneficial to this dehydration process. Orthogonal test was conducted under different vapor feed flow rates, bed temperatures and bed heights, to obtain optimal fixed-bed dehydration condition. Dynamic saturated adsorbance was also studied. It was found that CSA has the same water adsorption capacity(0.15 g/g)as some commercial molecular sieves. Besides, this biosorptive dehydration process was found to be the most energy-efficient compared with other ethanol purification processes.

Identification of Volatile Compounds in Codfish(Gadus) by a Combination of Two Extraction Methods Coupled with GC-MS Analysis

Codfish is a kind of abyssal fish species with a great value in food industry. However, the flavor of codfish, especially the unpleasant odor, has caused serious problems in its processing. To accurately identify the volatile compounds in codfish, a combination of solid phase micro-extraction(SPME) method and simultaneous distillation extraction(SDE) method was used to extract the volatiles. Gas chromatography-mass spectrometry(GC-MS) along with Kovats indices(KI) and authentic standard compounds were used to identify the volatiles. The results showed that a total of 86 volatile compounds were identified in codfish, of them 24 were extracted by SDE, 69 compounds by SPME, and 10 compounds by both SDE and SPME. Seventy volatile compounds were found to have specific odors, of them 7 typical compounds contributed significantly to the flavor of codfish. Alcohols(i.e.,(E)-2-penten-1-ol and 2-octanol), esters(i.e., ethyl butyrate and methyl geranate), aldehydes(i.e., 2-dodecenal and pentadecanal) contributed the most to fresh flavor while nitrogen compounds, sulphur compounds, furans, as well as some ketones(i.e., 2-hydroxy-3-pentanone) brought unpleasant odor, such as fishy and earthy odor. It was indicated that the combination of multiple extraction methods and GC-MS analysis can enhance the accuracy of identification, and provide a reference for the further study on flavor of aquatic products.