一株富油微藻的鉴定及其脂肪酸成分分析

富油微藻在生物柴油应用方面具有良好的应用前景,分析其脂肪酸的含量和成分对其有效利用具有理论指导意义。采用扩增18S r RNA片段对本试验所分离得到的一株富油微藻进行分子生物学鉴定,并分别用50%,65%和80%三种不同浓度的甲醇、乙醇和丙酮溶液作为溶剂,采用索式提取法抽提藻油,然后采用气相色谱-质谱联用(GC-MS)分析藻油中脂肪酸的含量及成分,并确定最佳的提取方案。结果表明,18S r RNA序列显示,该微藻属于角毛藻Chaetoceros dichaeta。有机溶剂抽提藻油时,50%甲醇的抽提效果最佳,提取效果随甲醇浓度增加而降低。乙醇的提取效果跟甲醇类似,而丙酮的提取效果随浓度提高有所改善,但总体效率不高。在最佳提取条件下,藻油产率达到了451.6 mg·g-1干藻。该角毛藻油中脂肪酸主要为饱和的14碳和16碳长链脂肪酸,含量分别为23.96%和68.58%。研究认为:该微藻属于角毛藻类,甲醇为比较适合的提取该微藻藻油的溶剂;该角毛藻富含长链脂肪酸,在生物柴油等绿色能源行业具有良好的应用价值。

卷烟过程中过滤嘴处硬质白丝的成分分析、形成原因及解决方法

在卷烟生产过程中,烟过滤嘴处形成了一种硬质白丝,经过分析并通过使用水、碘酒、三乙酸甘油酯、丙酮四种试剂以及气质联用色谱进行分析比对,确定该物质是丝束所形成。在卷烟生产现场,通过观察,发现是由于切割的圆刀片不快,刀片与磨砂轮摩擦导致刀片温度过高,使未被切断的丝束由于高温瞬间熔融后发硬所致。随后在切割处增加吹风管以降低刀片温度并且勤换刀片,问题得以解决。

苯酚在超(亚)临界水中的不完全氧化反应

利用间歇式反应装置研究苯酚超(亚)临界水氧化反应,以n(H2O2)n∶(苯酚)=3.6∶1投入反应,初步探讨了不同的温度、压力条件对反应中间产物的影响.气质谱联用仪分析结果显示:不完全氧化的主要产物包括乙醇、丙酮、呋喃,氯乙烯等;随着温度、压力的升高,中间产物的成分、含量随之变化.产生的中间产物还可以进一步回收利用.

彩色显像管一种类型的早期失效的机理研究

本文介绍了一批彩显管早期失效的性能特征和对其失效原因的诊断过程，我们先后采用了残气质谱分析，慢性漏气的快速无损检测以及氦质谱检漏等技术手段来寻找失效原因，从理论上分析了这类管子的早期失效机理并对相关问题进行了讨论，彩显管的早期失效并非仅这一种类型，应该针对其性能特征来具体分析。

彩色显像管早期失效的机理研究

介绍了几只彩色显像管早期失效的性能特征和对其失效原因的诊断过程。其间 ,我们先后采用了残气质谱分析、慢性漏气的快速无损检测以及氦质谱检漏等技术手段来寻找失效原因。文中 ,重点介绍了“慢漏快检”的原理及其检测结果 ;其后 ,从理论上分析了这类管子的早期失效机理并对相关问题进行了讨论。最后 ,总结出的一些对策在付诸实施后 ,已取得了良好的预防效果。彩色显像管的早期失效并非仅这一种原因 ,应该针对其性能特征来具体分析 ,本文只提供解决本类型早期失效管的一种方法 ,仅供参考。

水杨酸诱导的月季对甜菜夜蛾的抗性及机理研究

为探明外源水杨酸(SA)诱导月季产生的对甜菜夜蛾的抗性以及产生这种抗性的化学物质基础,采用双选生物测试方法测试了SA处理月季对甜菜夜蛾产卵行为的影响,用GC-MS分析了SA诱导的月季挥发性成分(VOCs)的变化,进一步研究了VOCs中的抗虫活性成分。1.0 mmol/L SA溶液处理月季植株可使甜菜夜蛾在植株上的产卵量显著减少(P<0.05),处理6、9、12 d后,总产卵量与对照相比分别减少了35.4%、38.9%、47.5%。进一步收集对照植株和处理植株顶空挥发性成分,分别配成溶液,喷施两组相同的未经处理的健康月季枝条,结果表明:在喷施了从处理植株上提取的挥发性成分混合物后,枝条上的产卵量与对照相比显著减少(P<0.05),处理6、9、12 d后,抑制指数分别为23.9%、25.4%、36.2%。GC-MS结果表明,SA诱导了月季挥发性成分显著变化。正常情况下2-乙基己酸、十四烷醇、棕榈酸甲酯、乙酸十六酯等化合物在健康植株中不会被合成,只有在SA诱导作用下才会被植株合成出来。SA对这4种化合物的诱导作用表现出明显的时间效应,并且它们对甜菜夜蛾产卵行为的抑制作用表现出明显的浓度效应。结果表明,外源SA处理使月季对甜菜夜蛾产生了诱导抗性,月季挥发性成分变化是这种抗性的重要物质基础。

Characterization of Specific Spoilage Bacteria and Volatile Flavor Compounds of Flavored Crayfish

It is a common issue in the processing industry of crayfish that flavored crayfish stored at room temperature is perishable.In order to establish an effective putrid prediction mechanism,high-throughput sequencing and solid phase microextraction gas chromatography-mass spectrometry(SPME-GCMS)were used to analyse the microbial community structure and volatile flavor compounds of normal and putrid crayfish.The results showed that Aeromonas(57%),Macrococcus(7.7%),Vibrio sp.(6.6%),Acinetobacter(5%),Citrobacter(4.9%)and Enterobacter(1.49%)were the main bacterial genus in the refrigerated fresh crayfish(HNA).And Staphylococcus(17.04%),Aeromonas(4.46%),Xanthomonas(4.16%),Streptococcus(4.62%)and Enterococcus(2.77%)were the main bacterial genus in the marinated and refrigerated crayfish(HND).With the spoilage of samples(HNE and HNC),the diversity of bacteria decreased,and the specific spoilage bacteria grew rapidly,mainly Enterococcus,Bacillus,Lactobacillus,Leuconostoc,Weissella.Meanwhile,the volatile compounds in non-spoilage sample(HNA and HND)were mainly alkane compounds,aldehydes compound and esters compounds;and the volatile compounds in spoilage samples were mainly alcohols,acids,benzene compounds,terpenoids,N-containing compounds,S-containing compounds and ethers.This indicated that the contents and types of volatile compounds changed with the sample spoilage and deterioration.Correlation analysis results showed that Enterococcus,Lactobacillus and Bacillus were significantly positively correlated with alcohols,acids,benzene,terpenoids,N-containing compounds,S-containing compounds and ether compounds,while Aeromonas,Megasphaera,Acinetobacter,Citrobacter and Vibrio were significantly positively correlated with alkane compounds and esters compounds,and Leuconostoc were significantly positively correlated with alcohol compounds.These results can provide a theoretical guidance for the storage of cooked flavor crayfish at room temperature.

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.

Chemical composition of the essential oil from Rabdosia lophanthoides

Gas chromatography/mass spectrometry (GC MS) of the essential oil from the aerial parts of Rabdosia lophanthoides resulted in the identification of 108 compounds representing 78.120% of the oil. Hydro distillation of Rabdosia lophanthoides yielded a pale yellow oil. The compounds identified and their relative proportions are listed in Table 1 according to their order of elution on an HP 5MS capillary column. .

Direct Fingerprinting Polycyclic Aromatic Hydrocarbons in Heavy Oils by PY-GC/MS and Its Application to Hydrotreating Processes

An efficient analytical method combining pyrolysis and capillary GC/MS has been developed for determination and quantitation of targeted polycyclic aromatic hydrocarbons.The limit of detection ranged from 0.29 μg/g to 43.46 μg/g,and repeatability values were between 0.1% and 8.2% for blank spiked samples and between 0.1 % and 9.8% for real samples of heavy oils.Through application of the proposed method in hydrotreating processes,it has been found out that heavy oils before and after the specified hydroprocessing treatment exhibited a diverse PAHs distribution which might be determined by the discrepancy in their intrinsic contents and hydrogenation reactivity.Furthermore,the hydrogenation reactivity of different polycyclic aromatic hydrocarbons was further investigated and discovered to be more interrelated to molecular structure and rings alignment or conjugation mode.

Study of oxidization of coal–pitch by O_3

For the purpose of obtaining small molecular and oxygen-containing aromatic compounds, taking a toluene-extracted coal pitch as the research object, the oxidation of coal-pitch by ozone （03） in formic acid was studied. The coal-pitch sample and the oxidized pitch residue were characterized by elementary analysis and Fourier transform infrared spectroscopy （FTIR）, while the small molecular products were analyzed by a gas chromatography-mass spectrometer （GC-MS）. The results show that the highest oxygen content of oxidized coal pitch had been acquired at a reaction temperature of 50℃C, an 03 flow rate of 6300 mg/h and a reaction time of 4 h. Quite a lot of hydroxyls and carbonyls were introduced into the structure of the oxidized coal-pitch, while the small molecules produced mainly involve nonpolar aro- matic compounds, aromatic anhydride and quinone compounds. It is speculated that the mechanism is direct electrophilic oxidation in which the molecules of 03 directly attack the aromatic ring at its carbon atoms with high electron density, and then generate hydroxyl or carbonyl until the aromatic ring cracks. This study shows that 03 can make the fused aromatic ring of coal-pitch become oxidized and depoly- merized, and hence the ozonization of coal-pitch can be a potential method for obtaining oxygen- containing aromatic compounds.

Determination of brominated diphenyl ethers in atmospheric particulate matter using selective pressurized liquid extraction and gas chromatography–mass spectrometry with a negative chemical ionization

This study describes the development and validation of a sensitive and reliable method for determination of polybrominated diphenyl ethers（PBDEs）in atmospheric particulate matter using selective pressurized liquid extraction（SPLE）and gas chromatography–mass spectrometry with a negative chemical ionization（GC-NCI-MS）.Extraction and clean-up were performed using PLE with 2 g florisil and 3 g silica placed in the extraction cells.Under optimal conditions,14 PBDEs were extracted at 70℃ using hexane/dichloromethane（50：50,v/v）as solvent.Validation of SPLE returned excellent recoveries for most analytes,with relative standard deviations mostly below20%.Method detection limits ranged from 0.13 to15.38 ng·mL^-1 for the GC-MS analyses.The method was successfully applied to atmospheric particulate matter of Beijing,where analytes were detected in the range of182.79 to 468.99 pg·m^-3.

Evaluation of Pesticide Residues in Mango by a Multi-residue Analysis and GC/MS Triple Quadrupole

Mango fruit has a great national and international market, and Brazilian production is 1,900 thousand tons/year exporting to North America and Europe. However, the loss could occur during the production when it is affected by pests and climate conditions, so the increased use of chemical substances and their presence should be monitored. A task for governmental agencies, producers and food sales, attending the sanitary barriers requirements, is to distribute food free from contaminants, so laboratories involved in this type of work usually employ multi-residues analysis. The objective of this study was to evaluate the presence of pesticide residues in mango using QuEChERS method and mass spectrometry technique. Positive samples were compared with Brazilian maximum residues level （MRL） and the health risk exposure was evaluated using the acute dietary intake （ADI） parameter. A total of 20 samples were collected from January to March, in Sao Paulo city markets. The recoveries were in the range of 70% to 120%, and standard deviation was below 20%. The category of pesticides not permitted for the crop were found in l0 samples; eight samples presented pesticides below MRL and two samples above MRL for the fungicide procloraz. The ADI values were below 20% of ADI for an adult and the worst case was dimethoate with 69% of ADI for children. The time spent in monitoring studies and the viability of method chosen must be considered by pesticide residues laboratories during routine analysis of food quality control.

Lipid Oxidation and Fatty Acid Composition in Salt-Dried Yellow Croaker(Pseudosciaena polyactis) During Processing

Lipid oxidation in salt-dried yellow croaker(Pseudosciaena polyactis) was evaluated during processing with commonly used analytical indices, such as the peroxide value(POV), the thiobarbituric acid reactive substances(TBARS) value, and oxidative-relative lipoxygenase(LOX) activity. Additionally, fatty acids were analyzed using gas chromatography-mass spectrometry. Both POV and TBARS increased significantly(P < 0.05) at the rinsing stage. POV reached its peak value of 3.63 meq O_2 per kg sample at the drying stage, whereas TBARS constantly increased from 0.05 to 0.20 mg MDA per kg sample. Processing of salt-dried yellow croaker had an extremely significant(P < 0.01) effect on LOX activity. Twenty-six fatty acids were identified. Combined eicosapentaenoic acid(EPA; C20:5n3) and docosahexaenoic acid(DHA; C22:6n3) content varied between(19.20 ±0.37) mg g^(-1) and(23.45 ± 1.05) mg g^(-1). The polyunsaturated fatty acid/saturated fatty acid(PUFA/SFA) ratio in yellow croaker was 0.73–1.10, and the n-6/n-3 PUFA ratio was approximately 0.13–0.20. The contents of most fatty acids varied significantly(P <0.05) during the different processing stages, and these differences were caused by lipid oxidation. C18:0, C16:1n7, C19:0, and C22:6n3 showed clear changes in principle component one of a principle components analysis. These fatty acids are potential markers for evaluating lipid oxidation in fish muscle because there was a significant correlation between these markers and TBARS and LOX activity(P < 0.05) with Pearson's coefficients > 0.931.

Oil-source correlation of Lower-Triassic oil seepages in Ni＇erguan village, Southern Guizhou Depression, China

There are abundant bitumens and oil seepages stored in vugs in a Lower-Triassic Daye formation(T_1d)marlite in Ni'erguan village in the Southern Guizhou Depression. However, the source of those oil seepages has not been determined to date. Multiple suites of source rocks of different ages exist in the depression. Both the oil seepages and potential source rocks have undergone complicated secondary alterations, which have added to the difficulty of an oil-source correlation. For example, the main source rock, a Lower-Cambrian Niutitang Formation"(∈_1n) mudstone, is over mature, and other potential source rocks, both from the Permian and the Triassic, are still in the oil window. In addition, the T_1d oil seepages underwent a large amount of biodegradation. To minimize the influence of biodegradation and thermal maturation, special methods were employed in this oil-source correlation study. These methods included catalytic hydropyrolysis, to release covalently bound biomarkers from the over mature"kerogen of ∈_1n mudstone, sequential extraction, to obtain chloroform bitumen A and chloroform bitumen C from the T_1d marlite, and anhydrous pyrolysis, to release pyrolysates from the kerogen of T_1d marlite. Using the methods above, the biomarkers and n-alkanes releasedfrom the oil samples and source rocks were analysed by GC–MS and GC-C-IRMS. The oil-source correlation indicated that the T_1d oil seepage primarily originated from"the ∈_1n mudstone and was partially mixed with oil generated from the T_1d marlite. Furthermore, the seepage also demonstrated that the above methods were effective for the complicated oil-source correlation in the Southern Guizhou Depression.

甲基六氢苯酐固化双酚A型环氧树脂的化学降解

分别采用四甲基氢氧化铵(TMAH)和对甲苯磺酸-乙酸酐(Ts OH-AA)降解甲基六氢苯酐固化的双酚A型环氧树脂,并通过气相色谱-质谱(GC-MS)分析了降解产物中的可气化成分。结果表明,TMAH降解反应生成了甲基六氢邻苯二甲酸二甲酯,说明TMAH切断了固化物交联网络中的酯键。Ts OH-AA降解反应生成了甘油三乙酸酯和苯基甘油醚二乙酸酯,推测Ts OH-AA不仅切断了固化物交联网络中的碳氧醚键,而且切断了酯键和苯碳键。本研究为解析和理解酸酐固化环氧树脂的成分提供了新的思路。

Marine Bacterial Biofilms in Bioremediation of Polycyclic Aromatic Hydrocarbons(PAHs) Under Terrestrial Condition in a Soil Microcosm

Polycyclic aromatic hydrocarbons （PAHs） in soil retain for a quite long period due to their hydrophobicity and aggregation properties. Biofilm-forming marine bacterial consortium （named as NCPR）, composed of Stenotrophomonas acidaminiphila NCW702, Alcaligenes faecalis NCW402, Pseudomonas mendocina NR802, Pseudornonas aeruginosa N6P6, and Pseudomonas pseudoalcaligenes NP103, was used for the bioremediation of PAHs in a soil microcosm. Phenanthrene and pyrene were used as reference PAHs. Parameters that can affect PAH degradation, such as chemotaxis, solubility of PAHs in extracellular polymeric substances （EPS）, and catechol 2,3-dioxygenase （C230） activity, were evaluated. P. aeruginosa N6P6 and P. pseudoalcaligenes NP103 showed chemotactic movement towards both the reference PAHs. The solubility of both the PAHs was increased with an increase in EPS concentration （extracted from all the 5 selected isolates）. Significantly （P 〈 0.001） high phenanthrene （70.29%） and pyrene （55.54%） degradation was observed in the bioaugmented soil microcosm. The C230 enzyme activity was significantly （P 〈 0.05） higher in the bioaugmented soil mi- crocosm with phenanthrene added at 173.26 ± 2.06 nmol rain-1 mg-1 protein than with pyrene added at 61.80 ± 2.20 nmol min-1 mg-1 protein. The C230 activity and gas chromatography-mass spectrometer analyses indicated catechol pathway of phenanthrene metabolism. However, the metabolites obtained from the soil microcosm added with pyrene revealed both the catechol and phthalate pathways for pyrene degradation.

Olivine versus peridotite during serpentinization:Gas formation

The dependence of starting materials and their initial grain sizes on the formation of gases （H2, CH4, C2H6 and C3Hs） during serpentinization was investigated by conducting hydrothermal experiments at 311℃ and 3 kbar on olivine and peridotite with initial grain sizes ranging from 〈30 to 177 μm. Hydrocarbons （CH4, C2H6 and C3H8） were produced from reaction between dissolved CO2 in the starting fluids and HE formed during serpentinization, which were analyzed by Gas Chromatography. It was found that olivine serpentinization produced much less H2 and CH4 compared with those after peridotite alteration, while their C2H6 and C3H8 were identical. For example, for olivine with initial grain sizes of 〈30 μm, the amounts of HE and CH4 were 79.6 mmol/kg and 460 μmol/kg after 27 days, respectively. By contrast, the quantities of H2 and CH4 produced in experiment on peridotite with the same run duration were much larger, 119 mmol/kg and 1300 μmol/kg, respectively. This indicates that spinel and pyroxene in peridotite may increase the amounts of HE and hydrocarbons, possibly due to the catalytic effect of aluminum released by spinel and pyroxene during serpentinization. Moreover, the production of H2 and hydrocarbons is negatively correlated with initial grain sizes of the starting material, with smaller amounts of HE and hydrocarbons for larger initial grain sizes, indicating that the kinetics of serpentinization influences the formation of HE and hydrocarbons, possibly because of the lack of catalytic minerals for the starting material with larger grain sizes. This study suggests that olivine cannot completely represent peridotite during serpentinization, and that H2 and hydrocarbons in hydrothermal fields near the mid-ocean ridge may be produced in a very long period of serpentinization or the presence of catalytic minerals due to large grain sizes of ultramafic rocks.

A chemometric method to identify selective ion for resolution of overlapping gas chromatography-mass spectrometry signal

A chemometric method to determine selective ion by using non-negative immune algorithm （NNIA） was proposed. In the method, the mutual projections of the chromatographic profiles at different m/z channel are calculated using NNIA. Suppose a GC-MS data with m retention time points and n mass channels, the projections of the GC-MS data onto a chromatographic profile at a mass channel will form a mass spectrum of ln vector. If the chromatographic profile at a selective mass channel is used, the extracted mass spectrum will be a correct one. Therefore, by comparing the extracted mass spectrum with a reference spectrum, the selective ion can be identified, and the corresponding chromatographic profile can be obtained at the same time. GC-MS data of 40-pesticide mixture was investigated by the method. The results show that both the mass spectral and the chromatographic information of the interested components can be extracted from the overlapping signals, except for the special cases of isomeric components with very similar mass spectra.