Analyzing crude oils from the Junggar Basin(NW China) using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry(GC×GC-TOFMS)

As a new technology of analyzing crude oils, comprehensive two-dimensional gas chromatography cou- pled with time-of-flight mass spectrometry （GCxGC- TOFMS） has received much research attention. Here we present a case study in the Junggar Basin of NW China. Results show that the hydrocarbons, including saturates and aromatics, were all well-separated without large co- elution, which cannot be realized by conventional one-dimensional GC-MS. The GC×GC technique is especially effective for analyzing aromatics and low-to-middle- molecular-weight hydrocarbons, such as diamondoids. The geochemical characteristics of crude oils in the study area were investigated through geochemical parameters extracted by GC×GC-TOFMS, improving upon the understanding obtained by GC-MS. Thus, the work here represents a new successful application of GC×GC- TOFMS, showing its broad usefulness in petroleum geochemistry.

Identification and Characterization of Sulfur Compounds in Straight-Run Diesel Using Comprehensive Two-Dimensional GC Coupled with TOF MS

The solid-phase extraction using Pd-Al2O3 as the stationary phase was employed to pre-separate the sulfur compounds in straight-run diesel. The isolating effect was evaluated quantitatively by gas chromatography with a sulfur chemiluminescence detector to harvest a satisfactory result. The identification of the structure of sulfur compounds by comprehensive two-dimensional gas chromatography coupled with the time-of-flight mass spectrometry indicated that cyclo-sulfides, benzothiophenes, dibenzothiophenes, dihydro-benzothiophenes and tetrahydro-dibenzothiophenes were included in straightrun diesel obtained from the Arab medium crude(AM). A total of 259 individual compounds were detected and their molecular structures were identified. The analytical method was approved as an effective way to characterize the composition of sulfur compounds, which reduced the interference of other compounds, facilitated the data presentation and provided more detailed information about molecular composition of sulfur compounds.

基于便携GC-MS和HS/SPME-GC×GC-TOF MS分析化州橘红与广西橘红成分差异

为探究不同产地橘红挥发性成分之间的差异,本研究采用便携气相色谱-质谱(GC-MS)和顶空固相微萃取结合全二维气相色谱-飞行时间质谱(GC×GC-TOF MS)技术分析化州橘红和广西橘红的挥发性成分。结果表明,便携GC-MS只能初步区分化州橘红和广西橘红,不能确定化州橘红的特征标志物;利用主成分分析法(PCA)和正交偏最小二乘法(OPLS-DA)对GC×GC-TOF MS实验数据进行处理,根据|p(corr)|>9和|p|>0.06结合VIP>1.1,共筛选出10种化州橘红标志物。该研究为化州橘红药材的质量评价与鉴定提供了依据,也为其他中药质量评价提供了方法参考。

Determination of 7 Indictor Polychlorinated Biphenyls (PCBs) Residues in Porphyra by Ultrasonic Extraction and Gas Chromatography (GC)

A method was developed for determination of 7 indictors the polychlorinated biphenyls (PCBs) residues in porphyra by gas chromatography (GC) with electron capture detector (ECD). The PCBs were extracted with hexane/methylene chloride (1:1, v/v) by ultrasonic extraction and the samples were cleaned up by concentrated sulfuric acid and Alumina-N solid phase extraction cartridge. The analytes were quantified by an internal standard method. Under optimal experimental conditions, good linearity was observed in the range of 5 - 200 ng/mL and the correlation coefficients were 0.9994 - 0.9998. The limit of quantitation (LOQ) for target analytes ranged from 6.0 to 10.0 μg/kg. At the spiked levels of 10, 50, 100 μg/kg, the average recoveries ranged from 90.9% to 102% with the relative standard deviations 2.12% - 6.32%. The result showed that the proposed method was rapid, and could be used for the determination of the PCBs in porphyra.

基于GC×GC-TOF MS对太湖流域水体中有机物的非靶标识别

本研究基于全二维气相色谱-飞行时间质谱(GC×GC-TOF MS),采用非靶标筛选法分析太湖流域18个采样点的水样,通过特征离子峰、精确质量数、保留指数偏差和NIST谱库匹配,共识别出466种有机物,其中各采样点共有检出率超过80%的化合物有68种,主要是香精香料、工业化学品和多用途化合物,并识别出多种尚未纳入监管清单的化合物,如顺式-11-二十烯酰胺、地塞诺和γ-谷甾醇。对非靶标方法识别的化合物进行半定量计算,发现各类化合物的单体浓度在0.025~113.145μg/L之间波动,其中浓度较高的是顺式-11-二十烯酰胺、邻苯二甲酸二丁酯和地塞诺。通过聚类分析发现,新塘港和小梅口点位的水体污染较轻,主要受涂料行业排放的影响,其余采样点位污染较重,主要受工业和食品加工业的影响。此外,本研究还对检出的68种有机物的半定量浓度进行初步的生态风险评估,发现有22种污染物具有中等以上生态风险,其中的11种污染物具有高生态风险,这为评估水体有机物健康效应提供了参考。

全二维气相色谱/飞行时间质谱(GC×GC-TOFMS)用于烟叶中酸性成分的分离与分析

建立了烟叶中酸性化合物(挥发性、半挥发性羧酸类和酚类)组成研究的全二维气相色谱/飞行时间质谱(GC×GC-TOFMS)分析方法,并用此方法对香料烟中的酸性化合物进行了表征.用同时蒸馏萃取样品的前处理方法,采用TOFMS谱图库检索结合全二维特有的包含结构信息的二维谱图,通过族分离和结构谱图,鉴定出了香料烟中143种挥发性及半挥发性酸性组分,包括10种酸酐和呋喃二酮,43种有机酸和90种酚类化合物.同时对不同类别的化合物在二维气相色谱上的分布模式进行了研究.结果表明,全二维气相色谱飞行时间质谱的高分辨率非常适合于烟叶这类复杂体系的分离分析.

全二维气相色谱/飞行时间质谱(GC×GC/TOFMS)用于烟叶中挥发、半挥发性碱性化合物的组成研究

建立了烟叶中挥发性、半挥发性碱性化合物组成研究的全二维气相色谱/飞行时间质谱(GC×GC/TOFMS)分析方法,并用所建立的方法对香料烟中碱性化合物进行了表征.对比了一维气相色谱和全二维色谱方法用于烟叶碱性组分组成分析的效果.一维色谱质谱方法共鉴定出45种碱性化合物.用所建立的全二维气相色谱方法,采用TOFMS谱图库检索结合全二维特有的包含结构信息的二维谱图,通过族分离和结构谱图鉴定,鉴定出了香料烟中挥发性、半挥发性碱性组分共92种.包括吡咯类化合物6种,吡啶类化合物39种,吡嗪类化合物10种,苯胺类化合物11种,喹啉类化合物11种,吲哚类4种和其他类化合物11种.同时对不同类别的化合物在二维气相色谱上的分布模式进行了研究.研究结果表明,全二维色谱飞行时间质谱的高分辨率和特有的定性手段适合于烟叶这类复杂植物体系的化学组成研究.

自动固相微萃取(SPM E)GC-MS、GC-MS-MS法检测环境水中有机磷杀虫剂的研究

固相微萃取(solid-phase microextraction,SPME)是20世纪90年代发展起来的一种样品前处理技术,与传统的液-液提取、液-固提取相比,SPME更适用于提取、浓缩液态或气态的挥发性和半挥发性物质,SPME技术可将采样、萃取、浓缩和样本引入集中于一个步骤完成,尤其随着自动SPME与GC-MS等联用技术的日益完善,使SPME技术优点得到更充分的发挥.……

卷烟主流烟气粒相物中中性化学成分的全二维气相色谱飞行时间质谱(GC×GC-TOFMS)谱图特征识别

建立了全二维气相色谱-飞行时间质谱(GC×GC-TOF MS)分析卷烟主流烟气中中性化学成分的方法。以较长的弱极性柱HP-5MS(50 m×0.2 mm i.d.×0.33μm)作为第一维柱,较短的薄液膜中等极性柱DB-17MS(1.7 m×0.1 mm i.d.×0.1μm)作为第二维柱,对优质烟叶单料卷烟烟气的中性成分进行定性分析,经过人工纠错等分析初步鉴定出匹配度大于700的1 464种成分,重点讨论了中性香味羰基化合物全二维点阵的谱图特征,为烟气和复杂体系的深入研究提供了方法学基础。

广防己挥发油的GC-MS指纹图谱研究

防己药材主要分粉防己和木防己两类,木防己包括广防己和汉中防己.广防己为马兜铃科植物广防己Aristolochia fangchi Y.C.WuexL.D.Chou.et S.M.Hwang的干燥根[1],习称"木防己"、"水防己",主产于广东、广西,具有祛风止痛、清热利水之功效[2].……

GC-MS Analysis of Essential oil and n-Hexane Extract from Moso Bamboo

[Objective] This study aimed to analyze the chemical composition and yield of essential oil and n-hexane extract from moso bamboo to find active compounds with potential value. [Method] Essential oil and n-hexane extract were respectively extracted from moso bamboo of four different ages by using hydrodistillation and ultrasonic-assisted extraction with n-hexane, and analyzed with gas chromatography/mass spectrometry （GC/MS）. [Result] The results show that cedrol （46.39%） is the first principal volatile component in essential oil of the middle stem of 7-year old moso bamboo; dibutyl phthalate （59.46%） is the first principal volatile component in n-hexane extract of the middle stem of 3-year old moso bamboo; yield of n-hexane extract is higher than that of essential oil from moso bamboo. [Conclusion] Cedrol is an active compound with potential value.

GC×GC-TOF MS分析中国劲酒基酒挥发性成分

保健酒是以白酒或其他酒类为基酒,佐以中药材,对人体具有保健功效的酒饮料。中国劲酒是保健酒的代表产品之一,通常以清香型小曲酒为基酒,加入淮山药、仙茅、当归、肉苁蓉、枸杞子、黄芪、淫羊藿等药材经过现代提取与分离技术调配制成。采用液-液萃取结合全二维气相色谱-飞行时间质谱联用仪(comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry,GC×GC-TOF MS)对2种中国劲酒基酒的挥发性成分进行分析,测定其化合物的种类和含量。结果表明:2种中国劲酒基酒中初步定性出挥发性化合物175种,标准品定性化合物40种,其中醇类化合物41种、酯类化合物53种、醛酮类化合物24种、缩醛类化合物2种、酸类化合物24种、呋喃类化合物8种、酚类化合物3种、内酯类化合物8种、含氮化合物8种、含硫化合物1种和酸酐类化合物2种;含氮和含硫化合物在中国劲酒中为首次发现。液-液萃取结合GC×GC-TOF MS技术的分析方法可快速、准确分析鉴定出中国劲酒基酒中挥发性成分,结果旨在为中国劲酒的重要风味物质研究提供参考。

Identification of petroleum aromatic fraction by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry

Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry(GC×GC-TOFMS) is commercially available in the 1990s,with the characteristics of large peak capacity,high resolution,high sensitivity,etc.However,its application to the petroleum and geological analyses is just emerging in China and overseas.In this research,the analytical method for petroleum aromatic fraction using GC×GC-TOFMS is set up,via the choice of the column system and optimization of setting parameters,such as temperature programming,modulation time,hot pulse time,flow rate of carrier gas,data acquisition rate and data processing.The results indicate that different polar compounds of aromatic fraction distribute as bands on structured GC×GC chromatogram.Within each band,homologous compounds appear as a roof-tile structure based on the number of substituent residues.The aromatic compounds are identified and characterized according to the GC×GC chromatogram and mass spectra.According to the polarity and the number of rings,aromatic compounds are spatially present on one chromatogram,which directly reflects the distribution characteristics of complex compounds of aromatic hydrocarbons.In addition,quantitative analysis is favored as some overlapped peaks on traditional GC-MS chromatogram have been separated completely on GC×GC.Some heterocyclic atom aromatic compounds at trace level can be clearly identified using this method,for polarity differences from other interfered aromatic compounds.The development of this method and chromatogram recognition offer petroleum geologists a practical example for the application performance of GC×GC-TOFMS.

Comparison of geochemical parameters derived from comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry and conventional gas chromatography-mass spectrometry

The saturated and aromatic hydrocarbon fractions of crude oil samples have been analyzed by using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry （GCxGC-TOFMS） and conventional gas chro- matography-mass spectrometry （GC-MS）. In order to investigate the consistency and discrepancy of the obtained data from the two instruments, some petroleum geochemical parameters have been compared. A comparison of 23 geochemical parameters indicates that 10 parameters are comparable from the two instruments with less than 5% deviations. Therefore, GCxGC-TOFMS is equivalent to conventional GC-MS in some geochemical parameter acquisitions. However, the other 13 parameters are discrepant, including gammacerane / αβ-hopane, Ts/Tm, 2-ethyl-naphthalene / 1-ethyl-naphthalene （ENR）, （2, 6-dimethyl-naphthalene ＋2,7-dimethyl-naphthalene） / 1,5-dimethyl-naphthalene （DNR）, etc. Furthermore, compared to GCxGC-TOFMS, some low concentration compounds could not be detected by the conventional GC-MS, which results in the missing of related geochemical data. Normally, this is caused by the limited separation power and peak capacity of the conventional GC column. Besides, the co-eluting peak integrations are also affected significantly due to the incomplete separation of the compounds. Some low concentration compounds might not be detected because of the interference from the baseline noise or from other substances. GCxGC-TOFMS prevails in compound separation against the conventional GC-MS by avoiding co-elution, which achieves more accurate and precise peak area measurement with the presence of a true baseline. So petroleum geochemical parameters obtained from the GCxGC-TOFMS GCxGC-TOFMS may become one of the most effective analytical are more reliable than those from the conventional GC-MS tools for the oil and gas geochemical study.

A GC×GC-ToFMS Investigation of the Unresolved Complex Mixture and Associated Biomarkers in Biodegraded Petroleum

Heavy biodegraded crude oils have larger numbers of coeluting compounds than nonbiodegraded oils, and they are typically not resolved with conventional gas chromatography（GC）. This unresolved complex mixture（UCM） has been investigated using comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry（GC×GC-To FMS） within a set of biodegraded petroleums derived from distinct sedimentary basins, including northwestern Sichuan（Neoproterozoic, marine）, Tarim（Early Paleozoic, marine）, Bohai Bay（Eocene, saline/brackish） and Pearl River Mouth（Eocene, freshwater）. In general, the hydrocarbons that constitute the UCM in petroleum saturate fractions can be classified into three catalogues based on the distributions of resolved compounds on two dimensional chromatograms. Group 1 is composed mainly of normal and branched alkanes, isoprenoid alkanes and monocyclic alkanes; Group 2 comprises primarily terpanes ranging from two to five rings, and Group 3 is dominated by monoaromatic hydrocarbons such as tetralins and monoaromatic steranes. In addition, the UCM is source dependent and varies between oil populations. i.e., the UCM of petroleum derived from Precambrian and Early Paleozoic marine, Eocene saline/brackish and freshwater source rocks is specifically rich in higher homologues of A-norsteranes, series of 1,1,3-trimethyl-2-alkylcyclohexanes（carotenoid-derived alkanes）, and tetralin and indane compounds, respectively.

Qualitative Analysis of A Sulfur-fumigated Chinese Herbal Medicine by Comprehensive Two-Dimensional Gas Chromatography and High-Resolution Time of Flight MassSpectrometry Using Colorized Fuzzy Difference Data Processing

To investigate the chemical transformation of volatile compounds in sulfur-fumigated Radix Angelicae Sinensis. A comprehensive two-dimensional gas chromatography (GCxGC) and high-resolution time-of-flight mass spectrometry (HR-TOF/MS) with colorized fuzzy difference (CFD) method was used to investigate the effect of sulfur-fumigation on the volatile components from Radix Angelicae Sinensis. Twenty-five compounds that were found in sun-dried samples disappeared in sulfur-fumigated samples. Seventeen volatile components including two sulfur-containing compounds were newly generated for the first time in volatile oils of sulfur-fumigated Radix Angelicae Sinensis. The strategy can be successfully applied to rapidly and holistically discriminate sun-dried and sulfur-fumigated Radix Angelicae Sinensis. GCxGC-HR-TOF/MS based CFD is a powerful and feasible approach for the global quality evaluation of Radix Angelicae Sinensis as well as other herbal medicines.

Capillary gas chromatographic determination of dimethachlon residues in fresh tobacco leaves and cut-tobacco

Simple procedures for extraction and chromatographic determination of dimethachlon residues in fresh tobacco leaves and cut-tobacco are described.The determination was carried out by capillary gas chromatography(GC) with electron capture detection(ECD) and confirmed by GC-MS.The mean recoveries and relative standard deviation(RSD) were 93.2%～112.9% and 3.5%～6.7%,respectively at levels ranging from 0.01 to 0.1 mg/kg.The limit of determination was 0.001 mg/kg.Tobacco samples in routine check were successfully analyzed using the proposed method.

Analysis of residual crosslinking agent content in UV cross-linked poly(ethylene oxide) hydrogels for dermatological application by gas chromatography

Acrylates have been widely used in the synthesis of pharmaceutical polymers. The quantitation of residual acrylate monomers is vital as they are strong irritants and allergens, but after polymerization, are relatively inert, causing no irritation and allergies. Poly(ethylene oxide)(PEO) hydrogels were prepared using pentaerythritol tetra-acrylate(PETRA) as UV crosslinking agent. A simple, accurate, and robust quantitation method was developed based on gas chromatographic techniques(GC), which is suitable for routine analysis of residual PETRA monomers in these hydrogels. Unreacted PETRA was initially identified using gas chromatography–mass spectrometry(GC–MS). The quantitation of analyte was performed and validated using gas chromatography equipped with a flame ionization detector(GC–FID). A linear relationship was obtained over the range of 0.0002%–0.0450%(m/m) with a correlation coefficient(r2)greater than 0.99. The recovery( 4 90%), intra-day precision(%RSD o 0.67), inter-day precision(%RSD o2.5%), and robustness(%RSD o1.62%) of the method were within the acceptable values. The limit of detection(LOD) and limit of quantitation(LOQ) were 0.0001%(m/m) and 0.0002%(m/m), respectively.This assay provides a simple and quick way of screening for residual acrylate monomer in hydrogels.

Determining organic compounds in coking wastewater by SPME-GC /MS

The solid-phase microextraction （SPME） combined with gas chromatography/mass spectrometry （GC/MS） was used to determine and analyze organic pollutants in coking wastewater. Based on the fact that the main compounds in the wastewater were organics, some key parameters of the SPME were optimized. The method has good linearity （ its correlation coefficients 〉 0.99） in the range determined,its relative standard deviations （RSD） are less than 15%, and its recovery is from 87.9% to 128.1% with the lowest quantification limit of 5 ~g/L. This method has been used to measure 15 organic pollutants in wastewater from a certain coking plant. The results show that compared with the conventional method,it can save an hour in pretreatment time. It is a fast, low-cost, accurate, simple and efficient analytical method indeed.

Analysis on Volatile Components of Flowers and Leaves of Thymus mongolicus by SPME-GC/MS

[Objectives] To analyze volatile components of flowers and leaves of Thymus mongolicus. [Methods]Volatile components of collected T. mongolicus flower and leaves were separated by headspace solid-phase microextraction( SPME) and identified by gas chromatography/mass spectrometry( GC/MS) and normallized by peak area. [Results] A total of 24 and 14 compounds were identified from flowers and leaves of T. mongolicus in the total ion chromatogram,accounting for 99. 573% and 97. 187% of the total peak area,respectively. Main components of flowers and leaves of T. mongolicus include phenols and terpenes,and thymol accounts for 35. 38% and 49. 13% of flowers and leaves of T. mongolicus,respectively. [Conclusions] SPME-GC/MS can be applied in analyzing volatile components of flowers and leaves of T. mongolicus,to provide basis for further development and utilization of T. mongolicus.