沉香精油成分鉴定及其抗氧化、抑菌活性

为探究不同产地、不同提取方式的4种沉香精油的挥发性化学成分、抗氧化活性与抑菌活性的差异,采用气相色谱⁃质谱(gas chromatography⁃mass spectrometry,GC⁃MS)法对4种沉香精油的挥发性成分进行分析,结合其对1,1⁃二苯基⁃2⁃三硝基苯肼(1,1⁃diphenyl⁃2⁃picrylhydrazyl,DPPH)自由基、2,2'⁃联氮⁃二(3⁃乙基⁃苯并噻唑啉⁃6⁃磺酸)二铵盐[2,2'⁃azino⁃bis(3⁃ethylbenzothiazoline⁃6⁃sulfonic acid)ammonium salt,ABTS]阳离子自由基清除能力及对大肠杆菌、金黄色葡萄球菌、李斯特菌的抑制能力,对不同精油之间的抗氧化及抑菌活性进行对比。结果表明,从莞香超临界萃取精油(GXC)、莞香水蒸气蒸馏精油(GXS)、惠安超临界萃取精油(HAC)、惠安水蒸气蒸馏精油(HAS)中分别鉴定出69、50、66、62种挥发性成分。其中,倍半萜类含量分别为54.26%、89.94%、60.63%、70.38%;小分子芳香族类含量分别为5.42%、6.43%、4.43%、17.75%;色酮类含量分别为34.07%、0.00%、32.49%、1.34%。GXC、HAC、HAS表现出较强的抗氧化能力,对DPPH自由基的半数抑制浓度(half maximal inhibitory concentration,IC50)分别为0.66、0.36、1.32 mg/mL;对ABTS+自由基半数抑制浓度值分别为0.09、0.07、0.11 mg/mL,GXS抗氧化能力最弱。4种沉香精油在质量浓度为10 mg/mL时对大肠杆菌抑制作用低度敏感,对金黄色葡萄球菌、李斯特菌抑制作用中度敏感。不同沉香精油化合物组成差异赋予其独特的香气及功能活性,其中HAC抗氧化能力最强,GXC、HAC的抑菌效果最佳。

基于HS⁃SPME⁃GC⁃MS技术分析发酵条斑紫菜酱风味物质变化

该研究利用顶空固相微萃取气质联用技术(headspace⁃solid phase microextraction⁃gas chromatograph⁃massspectrometr,HS⁃SPME⁃GC⁃MS)对植物乳杆菌MMB⁃05组、干酪乳杆菌FJAT⁃7928组、混合组(植物乳杆菌MMB⁃05与干酪乳杆菌FJAT⁃7928体积比1∶1)和对照组发酵24 h和48 h条斑紫菜酱的挥发性物质进行检测,采用气味活度值(odor activity value,OAV),主成分分析(principal component analysis,PCA)及热图分析各发酵样品的关键性风味物质,在发酵后的紫菜酱中共鉴定出57种挥发性化合物,其中植物乳杆菌MMB⁃05组发酵24 h时酮类含量(29.03%)明显高于其他类别的化合物,干酪乳杆菌FJAT⁃7928和混合组烃类挥发性物质(45.39%和42.85%)占比最高。通过OAV和热图分析可知,在发酵24 h时,(Z)⁃2⁃庚烯醛、(E,Z)⁃2,6⁃壬二烯醛为4组样品酱香气起到主要贡献作用,但到发酵后期时,植物乳杆菌MMB⁃05组主要香气物质更多,且增加了L⁃乳酸OAV>1的关键风味成分,综合确定植物乳杆菌MMB⁃05组发酵的紫菜酱风味成分更丰富,整体风味更浓郁。

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.

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.

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.

Application of a Step-by-Step Fingerprinting Identification Method on a Spilled Oil Accident in the Bohai Sea Area

In recent years,oil spill accidents occur frequently in the marine area of China.Finding out the spilled oil source is a key step in the relevant investigation.In this paper,a step-by-step fingerprinting identification method was used in a spilled oil accident in the Bohai Sea in 2002.Advanced chemical fingerprinting and data interpretation techniques were used to characterize the chemical composition and determine the possible sources of two spilled oil samples.The original gas chromatography -flame ionization detec-tion (GC-FID) chromatogram of saturated hydrocarbons was compared.The gas chromatography-mass spectrometry (GC/MS) chromatograms of aromatic hydrocarbons terpane and sterane,n-alkane and poly-aromatic hydrocarbons (PAHs) were analyzed.The correlation analysis on diagnostic ratios was performed with Student’s t-test.It is found that the oil fingerprinting of the spilled oil (designated as sz1) from the polluted sand beach was identical with the suspected oil (designated as ky1) from a nearby crude oil refinery factory.They both showed the fingerprinting character of mixed oil.The oil fingerprinting of the spilled oil (designated as ms1) collected from the port was significantly different from oil ky1 and oil sz1 and was with a lubricating oil fingerprint character.The identification result not only gave support for the spilled oil investigation,but also served as an example for studying spilled oil accidents.

Study on oil–source correlation by analyzing organic geochemistry characteristics: a case study of the Upper Triassic Yanchang Formation in the south of Ordos Basin, China

In the south of the Ordos Basin, the oil source of the Upper Triassic Yanchang Formation is confused all the time, which affects further exploration. In this study, oil sources from the oil layers of Ch6, Ch8 and Ch9 are all analyzed and confirmed. Through their carbon isotope value and biomarkers, characteristics of crude oils from the Yanchang Formation are analyzed. Then, the oil–source relation is discussed, with the source rocks' features.Finally, the oil–source relation is calculated through cluster analysis. It is believed that the oils from the Yanchang Formation deposit in a similar redox environment, with weak oxidation–weak reduction, and have all entered maturity stage. Ch9 crude oil is more mature than crude oils from Ch6 and Ch8, and has more advanced plants and fewer algae. Gas chromatography(GC) and gas chromatography–mass spectrometry(GC–MS) analysis show that crude oils from Ch6 and Ch8 may come from Ch7, and Ch9 crude oil may not. Cluster analysis displays that crude oils from Ch6 and Ch8 have closer squared Euclidean distance with Ch7 source rocks than Ch9 crude oil does,indicating crude oils from Ch6 and Ch8 stem from Ch7 source rocks. And Ch9 crude oil has rather close squared Euclidean distance with Ch9 source rocks, illustrating Ch9 crude oil may be from Ch9 source rocks. This research may provide the theoretical basis for the next exploration deploy in the south of Ordos Basin.

Rapid and simultaneous determination of ten off-flavor compounds in water by headspace solid phase microextraction and gas chromatography-mass spectrometry

A simple and sensitive analytical procedure for the determination of multi-component compounds in water samples was developed and optimized using the headspace solid-phase microextraction(HSSPME) coupled with gas chromatography-mass spectrometry(GC-MS). Ten off-flavor compounds, including geosmin(GSM), 2-methylisoborneol(2-MIB), 2-isopropyl-3-methoxypyrazine(IPMP), 2-isobutyl-3-methoxypyrazine(IBMP), β-ionone, trans-2,cis-6-nonadienal(NDE), 2,3,4-trichloroanisole(2,3,4-TCA), 2,3,6-trichroloanisole(2,3,6-TCA), 2,4,6-trichloroanisole(2,4,6-TCA), and 2,4,6-tribromoanisole(2,4,6-TBA) were used as the target analytes. The optimization of extraction parameters including fibers types, extraction time, extraction temperature, stirring rate, sample volume, and ionic strength was carried out through the univariate approach. Ten off-flavor compounds were quantified within 50 min under the optimal conditions. Calibration curves with good linearity(r^2=0.990-0.998) were obtained in the range 1.0/2.0-100 ng/L, while the limits of detection for all compounds were lower than or close to the odor threshold concentration. Furthermore, the proposed method was applied to analyzing and determining the off-flavor compounds in real water samples from water-treatment plants.

Antimicrobial Activity of Ulva reticulata and Its Endophytes

Seaweeds are known to exhibit various antimicrobial properties, since it harbours an enormous range of indigenous bioactive compounds. The emergence of drug resistant strains has directed to the identification of prospective metabolites from seaweed and its endophytes, thereby exploiting the properties in resisting bacterial diseases. The current study was aimed to assess the antimicrobial activity of extracts obtained from Ulva reticulate, for which metabolites of Ulva reticulata and its endophytes were extracted and assessed against human pathogens like Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, and Bacillus subtilis. It was observed that the hexane extract of isolate VITDSJ2 was effective against all the tested pathogens but a significant inhibition was observed for Staphylococcus aureus and Escherichia coli. Further, Gas chromatography coupled with Mass spectroscopy （GC-MS） revealed the existence of phenol, 3, 5-bis （1, 1-dimethylethyl） in the crude hexane extract which is well-known to possess antibacterial activity. The effective isolate VITDSJ2 was identified to be the closest neighbour of Pseudomonas smtzeri by phenotypic and genotypic methods. The crude extracts of the seaweed Ulva reticulata was also screened for antibacterial activity and the hexane extract was effective in showing inhibition against all the tested pathogens. The compound in the crude extract of Ulva reticulata was identified as hentriacontane using GC-MS. The extracts obtained from dichloromethane did not show significant activity in comparison with the hexane extracts. Hence the metabolites of Ulva reticulata and the bacterial secondary metabolites of the endophytes could be used in the treatment of bacterial infections.

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.

Study on the basic nitrogen compounds from coal-derived oil

The distillation range analysis and elemental analysis of fractioned direct liquefied oil were conducted. Each fraction of liquefied oil contains some nitrogen compounds. Using the acid extraction method and gas chromatography/mass spectrometry （GC-MS）, the basic nitrogen compounds have been separated and identified. Compared with the nitrogen content of the liquefied oil before and after separation, the basic nitrogen compounds account for more than half of all nitrogen compounds. The basic nitrogen compounds in the light liquefied oil are easily separated, and contain more types of basic nitrogen compounds. The results also show that there are many basic nitrogen compounds in liquefied oil, such as pyrrole, aniline, pyridine, quinoline and so on. However, there are fewer other types of basic nitrogen compounds.

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.

Diethylstilbestrol in Fish Tissue Determined Through Subcritical Fluid Extraction and with GC-MS

As the key point in sex hormone analysis, sample pre-treatment technology has attracted scientists' attention all over the world, and the development trend of sample preparation forwarded to faster and more efficient technologies. Taking economic and environmental concerns into account, subcritical fluid extraction as a faster and more efficient method has stood out as a sample pre-treatment technology. This new extraction technology can overcome the shortcomings of supercritical fluid and achieve higher extraction efficiency at relatively low pressures and temperatures. In this experiment, a simple, sensitive and efficient method has been developed for the determination of diethylstilbestrol(DES) in fish tissue using subcritical 1,1,1,2-tetrafluoroethane(R134a) extraction in combination with gas chromatography-mass spectrometry(GC-MS). After extraction, freezing-lipid filtration was utilized to remove fatty co-extract. Further purification steps were performed with C_(18) and NH_2 solid phase extraction(SPE). Finally, the analyte was derived by heptafluorobutyric anhydride(HFBA), followed by GC-MS analysis. Response surface methodology(RSM) was employed to optimizing the extraction condition, and the optimized was as follows: extraction pressure, 4.3 MPa; extraction temperature, 26℃; amount of co-solvent volume, 4.7 m L. Under this condition, at a spiked level of 1, 5, 10 μg kg^(-1), the mean recovery of DES was more than 90% with relative standard deviations(RSDs) less than 10%. Finally, the developed method has been successfully used to analyzing the real samples.

Comparative analysis of volatile constituents between herbal pair flos lonicerae-caulis lonicerae and its single herbs

Gas chromatography-mass spectrometry(GC-MS) and the chemometric resolution method(alternative moving window factor analysis,AMWFA) were used for comparative analysis of volatile constituents in herbal pair(HP) flos lonicerae-caulis lonicerae(FL-CL) and its single herbs.The temperature-programmed retention index(PTRI) was also employed for the identification of compounds.In total,44,39,and 50 volatile chemical components in volatile oil of FL,CL and HP FL-CL were separately determined qualitatively and quantitatively,accounting for 87.22%,94.54% and 90.08% total contents of volatile oil of FL,CL and HP FL-CL,respectively.The results show that there are 32 common volatile constituents between HP FL-CL and single herb FL,33 common volatile constituents between HP FL-CL and single herb CL,and 10 new constituents in the volatile oil of HP FL-CL.

Assessing the kinetic model of hydro-distillation and chemical composition ofAquilaria malaccensis leaves essential oil

This study aimed to model the kinetic of hydro-distillation of Aquilaria malaccensis leaves oil in order to understand and optimize the extraction process. In addition, this study, for the first time, aimed to identify the chemical compositions of the A. rnalaccensis leave-oil. By assessing both first-order kinetic model and the model of simultaneous washing and diffusion, the result indicated that the model of simultaneous washing and diffusion better describes the hydro-distillation mechanism of the essential oil from A. rnalaccensis leaves. The optimum time, solid to liquid ratio, and the heating power for extracting the highest amount of essential oil were found to be around 3 h, 1：10 （g. ml-1）, and 300 W respectively. Yellow essential oil with a strong smell and a yield of 0.05 v/w was extracted by hydro-distillation Clevenger apparatus. Chemical compounds of the essential oil were analyzed using gas chromatography-mass spectroscopy （GC/MS）, which resulted in identification of 42 compounds that constitute 93% of essential oil. Among the identified components, Pentadecanal （32.082%）, 9-Octadecenal, （Z） （15.894%）, and Tetradecanal （6.927%） were the major compounds. Considering the fact that all the identified major components possess pesticidal properties, A. malaccensis leaves can be regarded as a promising natural source for producing pesticides.

Separation of arenols from a high-temperature coal tar

A high-temperature coal tar collected from Xuzhou Coking Plant, Saint-Gobain Pipelines （Xuzhou） Co., Ltd. was exhaustively extracted with petroleum ether （PE）. The extract was sequentially eluted through silica gel with PE and PE/ethyl acetate （EA） mixed solvents （volume ratio 2：1 ） to afford two eluted frac- tions. The extract and eluted fractions were analyzed with gas chromatography/mass spectrometry. In total, 14 arenols were detected, including phenol, cresols, xylenols, fluorenols, phenanthren-3-ol and pyren-l-ol.

Quantitative analysis of trace levels of β-ionone in water by liquid-liquidphase extraction-gas chromatography-mass spectrometry(LLE-GC-MS)

A simple and rapid technique based on liquid-liquid extraction coupled to gas chromatography-mass spectrometric detection(LLE-GC-MS) was developed for analysis of taste and odour compound β-ionone in water. Instrument parameters including programmed oven temperature, injection temperature and ion source temperature were evaluated and optimized. Effects of extraction time, ionic strength and p H on the detection efficiency were investigated and optimum conditions were 8 min of extraction time, without Na Cl addition at p H=9. Good linearity(R2=0.9997) was obtained when the linear range was 10-500 μg/L. The recoveries of β-ionone in ultrapure water and tap water samples were 88%-95% and 110%-114%, respectively. The relative standard deviations(RSD) were less than 10%. The method detection limit(MDL) and rejection quality level(RQL) were achieved at1.98 μg/L and 6.53 μg/L, respectively. LLE-GC-MS was demonstrated to be a rapid and convenient method for the determination ofβ-ionone in water samples.

Assessment of Triazine Herbicides in Soil by Microwave-assisted Extraction Followed by Gas Chromatography Coupled to Mass Spectrometry Detection

An alternative and fast method for the analysis of a mixture of nine triazines herbicides in soil is presented. The method is based on MAE （microwave-assisted extraction） of herbicides using ethyl acetate as extractant. The economy in the use of solvents coupled with the decrease in extraction time and lower power consumption make MAE a technique that meets the principles of green chemistry. MAE operational parameters, extraction time, mass of the sample and extraction temperature, were optimized by RSM （response surface methodology）. Determination of analytes was completed using gas chromatograph coupled to mass spectrometry detection. The selected triazines could be efficiently extracted by the solvent at 80 ℃ for 10 min, with 80% output of maximum power. When the optimized method was applied to analysis samples, the recoveries of analytes ranged from 81.8 to 106.0% and relative standard deviations were lower than 8.41%. The method is stable and reasonable, which can be used for the determination of ninetriazine herbicides residues in soil.

Pyrolysis of Polytrimethylene Terephthalate(PTT) Fiber by Pyrolysis Gas Chromatography-Mass Spectroscopy

Pyrolysis of polytrimethylene terephthalate(PTT) fiber has been investigated by pyrolysis gas chromatography-mass spectroscopy in the temperature range from 400℃ to 750℃ in order to observe the possible effect of the temperature on its composition of pyrolysates.At 400℃,pyrolysis of molecular chain could occur,only 13 pyrolysates could be identified.The trimethylene moieties bound to the macromolecular core by ester bonds are cleaved at around 400℃.At 550℃-750℃,pyrolysis of molecular chain could completely take place,46 pyrolysates could be found.As the temperature increases,the compositions of pyrolysate are distinctly increased.Several compounds,especially benzoic acid,monopropenyl-p-phthalate,2-propenyl benzoate,di-2-propenyl ester,1,4-benzenedicarboxylic acid,benzene,1,5-hexadiene,biphenyl and 1,3-propanediol dibenzoate could be formed.The thermal degradation mechanism,which is determined by structure and amount of the thermal decomposition products,are described.During pyrolysis of polytrimethylene terephthalate,polymeric chain scissions take place a peeling reaction as a successive removal of the dimer units from the polymeric chain.The chain scissions are followed by the elimination reaction,linkage action and secondary reactions,which bring about a variety fragment.

Gas Chromatography-Based Fingerprinting and Chemical Pattern Recognition of Rosa multiflora Volatile Oil

In this paper, gas chromatography-mass spectrometry （GS-MS） was used to build the standard fingerprint of volatile oil from Rosa multiflora Thunb. from 12 different habitats. Fourteen components in the volatile oil were identified as the indicator components ofR. multiflora, of which one was selected as the standard. The GC analysis conditions used for fingerprinting afford a very good separating effect. The similarity of the 12 volatile oils from R. multiflora Thunb. was more than 0.84, and the precision, stability and repeatability of the fingerprints were quite good. It could be concluded that the fingerprints can be used as the standard and as a quality control method for medicinal materials from R. multiflora Thunb..