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 coupled with time-of-flight mass spectrometry(GC×GCTOFMS) 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 coelution,which cannot be realized by conventional one-dimensional GC-MS.The GC×GC technique is especially effective for analyzing aromatics and low-to-middlemolecular-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×GCTOFMS,showing its broad usefulness in petroleum geochemistry.

Headspace Solid-Phase Micro-Extraction Gas Chromatography/Mass Spectrometry(HS-SPME-GC/MS)-Based Untargeted Metabolomics Analysis for Comparing the Volatile Components from 12 Panax Herbal Medicines

Quality control of ginseng currently is mainly based on ginsenoside analysis,but rarely focuses on the volatile organic components.In the current work,an untargeted metabolomics approach,by headspace solid-phase micro-extraction gas chromatography/mass spectrometry(HS-SPME-GC/MS),was elaborated and further employed to holistically compare the compositional difference of the volatile components simultaneously from 12 Panax herbal medicines,which included P.ginseng(PG),P.quinquefolius(PQ),P.notoginseng(PN),red ginseng(PGR),P.ginseng leaf(PGL),P.quinquefolius leaf(PQL),P.notoginseng leaf(PNL),P.ginseng flower(PGF),P.quinquefolius flower(PQF),P.notoginseng flower(PNF),P.japonicus(PJ),and P.japonicus var.major(PJvm).Chromatographic separation was performed on an HP-5MS elastic quartz capillary column using helium as the carrier gas,enabling good resolution within 1 h.We were able to characterize totally 259 volatile compounds,including 82 terpenes(T),46 alcohols(Alc),29 ketones(K),25 aldehydes(Ald),21 esters(E),and the others.By analyzing 90 batches of ginseng samples based on the untargeted metabolomics workflows,236 differential ions were unveiled,and accordingly 36 differential volatile components were discovered.It is the first report that simultaneously compares the compositional difference of volatile components among 12 Panax herbal medicines,and useful information is provided for the quality control of ginseng aside from the well-known ginsenosides.

Structure Elucidation of a New Toxin from the Mushroom Cortinarius rubellus Using Gas Chromatography-Mass Spectrometry (GC-MS)

Cortinarius orellanus (Fries) and C. rubellus (Cooke),which were formerly also known as C. speciosissimus, are poisonous mushrooms containing the toxin orellanine and several degradation products of orellanine,includingorelline and orellinine. Mass intoxication by poisonous mushrooms was observed in Poland in 1952-1957 [1]. In 1957, the cause of these outbreaks was described by Grzymala as poisoning by a member of the Cortinarius family. The toxin orellanine was first isolated from C. orellanusby Grzymala in 1962;the chemical structure of orellanine was later determined to be 3,3',4,4'-tetrahydroxy-2,2'-bipyridine-N,N'-dioxide. Poisoning with C. orellanus and C. rubellus has a very specific character. The first symptoms of intoxication usually do not appear until 2-3 days after ingestion, but in some cases intoxication appears after three weeks. The target organ for the toxin is the kidney. Histologically, it is easy to record the specific damage. The presence of degradation products of orellanine in kidney can be confirmed chromatographically, suggesting that the cause of poisoning is orellanine. However, the presence of orellanine in the blood of intoxicated persons has not been directly detected. A specific model was developed by Brondz et al. for the detection of orellanine, orelline, and orellininein animal stomach fluids [2-4]. The hypothesis that the fungal toxin orellanine as a diglucoside can be transported from the digestive system by the blood to the kidney could not be supported. The toxin orellanine as a diglucoside is very unstable in an aqueous acidic environment.[i1]?However, in the present study, it was possible to record an additional substance in animal stomach fluids using GC-MSafter ingestion ofC. rubellus. This substance, which has been namedrubelline, is part of a toxic mixture inC. orellanusandC. rubellusand is closely related to orellanine. The structure of rubelline is more suitable than orellanine for absorptionfromthe digestive tract and for transport in the blood. The presented hypothesis is that rubellineis absorbed in the digestive tract and transportedin the blood to the kidney, where it is biotransformed to orellanine and accumulatedto toxic levels. The process of biotransformationis in itself also damaging for the kidney and liver.[i2]?GC-MS instrumentation enables the separation of substances in biological samples and in the extract fromC. rubellus. The GC-MS with SMB technique was used to record the mass ion and to record a detailed fragmentation picture.

Metabolomics of gastric cancer metastasis detected by gas chromatography and mass spectrometry

AIM:To elucidate the underlying mechanisms of metastasis and to identify the metabolomic markers of gastric cancer metastasis.METHODS:Gastric tumors from metastatic and nonmetastatic groups were used in this study.Metabolites and different metabolic patterns were analyzed by gas chromatography,mass spectrometry and principal components analysis (PCA),respectively.Differentiation performance was validated by the area under the curve (AUC) of receiver operating characteristic curves.RESULTS:Twenty-nine metabolites were differentially expressed in animal models of human gastric cancer.Of the 29 metabolites,20 were up-regulated and 9 were down-regulated in metastasis group compared to non-metastasis group.PCA models from the metabolite profiles could differentiate the metastatic from the nonmetastatic specimens with an AUC value of 1.0.These metabolites were mainly involved in several metabolic pathways,including glycolysis (lactic acid,alaline),serine metabolism (serine,phosphoserine),proline metabolism (proline),glutamic acid metabolism,tricarboxylic acid cycle (succinate,malic acid),nucleotide metabolism (pyrimidine),fatty acid metabolism (docosanoic acid,and octadecanoic acid),and methylation(glycine).The serine and proline metabolisms were highlighted during the progression of metastasis.CONCLUSION:Proline and serine metabolisms play an important role in metastasis.The metabolic profiling of tumor tissue can provide new biomarkers for the treatment of gastric cancer metastasis.

Gas chromatography/mass spectrometry based metabolomic study in a murine model of irritable bowel syndrome

AIM To study the role of microbial metabolites in the modulation of biochemical and physiological processes in irritable bowel syndrome(IBS).METHODS In the current study, using a metabolomic approach, we analyzed the key metabolites differentially excreted in the feces of control mice and mice with IBS, with or without Clostridium butyricum(C. butyricum) treatment. C57 BL/6 mice were divided into control, IBS, and IBS + C. butyricum groups. In the IBS and IBS + C. butyricum groups, the mice were subjected to water avoidance stress(WAS) for 1 h/d for ten days. Gas chromatography/mass spectrometry(GC-MS) together with multivariate analysis was employed to compare the fecal samples between groups. RESULTS WAS exposure established an appropriate model of IBS in mice, with symptoms of visceral hyperalgesia and diarrhea. The differences in the metabolite profiles between the control group and IBS group significantly changed with the progression of IBS(days 0, 5, 10, and 17). A total of 14 differentially excreted metabolites were identified between the control and IBS groups, and phenylethylamine was a major metabolite induced by stress. In addition, phenylalanine metabolism was found to be the most relevant metabolic pathway. Between the IBS group and IBS + C. butyricum group, 10 differentially excreted metabolites were identified. Among these, pantothenate and coenzyme A(Co A) biosynthesis metabolites, as well as steroid hormone biosynthesis metabolites were identified as significantly relevant metabolic pathways.CONCLUSION The metabolic profile of IBS mice is significantly altered compared to control mice. Supplementation with C. butyricum to IBS mice may provide a considerable benefit by modulating host metabolism.

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.

Determination of 8 Diuretics and Probenecid in Human Urine by Gas Chromatography-Mass Spectrometry: Confirmation Procedure

A fast and sensitive method for determination of 8 diuretics (acetazolamide, bendroflumethiazide, bumetanide, chlorthalidone, furosemide, hydrochlorothiazide, metolazone, triamterene) and masking agent (probenecid) in human urine using gas-chromatography with mass spectrometric detection is described. The extraction of the substances as function of the nature of organic solvent, mixing time and pH of aqueous phase was studied. The tandem mass spectrometry was used to increase selectivity of diuretics determination due to elimination of background interferences. Fragmentation reactions were studied for each compound and their collision energies were optimized to obtain the best selectivity. The results of method’s validation demonstrate its suitability in routine analysis for confirmation purposes.

Occurrence of <i>N</i>-Acyl Homoserine Lactones in Extracts of Bacterial Strain of <i>Pseudomonas aeruginosa</i>and in Sputum Sample Evaluated by Gas Chromatography–Mass Spectrometry

This study presents a fast, accurate and sensitive technique using gas chromatography-mass spectrometry (GC-MS) for the identification and quantification of N-acyl homoserine lactones (AHLs) in the extracts of bacterial strain of Pseudomonas aeruginosa and sputum sample of a cystic fibrosis patient. This method involves direct separation and determination of AHLs by using GC-MS as simultaneous separation and characterization of AHLs were possible without any prior derivatiza-tion. Electron ionization resulted in a common fragmentation pattern with the most common fragment ion at m/z 143 and other minor peaks at 73, 57 and 43. The limit of detection for N-butanoyl, N-hexanoyl, N-octanoyl, N-decanoyl, N-dodecanoyl and N-tetradecanoyl homoserine lactones was 2.14, 3.59, 2.71, 2.10, 2.45 and 2.34 μg/L, respectively. The presence of AHLs in the culture of P. aeruginosa strain and spu-tum of a cystic fibrosis patient was achieved in selected ion monitoring (SIM) mode by using the prominent fragment at m/z 143.

Analysis of volatile components in a Chinese fish sauce,Fuzhou Yulu, by gas chromatography-mass spectrometry

Volatile components of Fuzhou Yulu, a Chinese fish sauce, were analyzed by gas chromatography-mass spectrometry (GC-MS), and two pretreatment methods, i.e., purge and trap (P&T) GC-MS and ethyl acetate extraction followed by GC-MS, were compared. P&T-GC-MS method determined 12 components, including sulfur-containing constituents (such as dimethyl disulfide), nitrogen-containing constituents (such as pyrazine derivatives), aldehydes and ketones. Ethyl acetate extraction fol- lowed by GC-MS method detected 10 components, which were mainly volatile organic acids (such as benzenepropanoic acid) and esters. Neither of the two methods detected alcohols or trimethylamine. This study offers an important reference to determine volatile flavor components of traditional fish sauce through modern analysis methods.

Speciation of Volatile Selenium Species in Plants Using Gas Chromatography/Inductively Coupled Plasma Mass Spectrometry

Gas chromatography/inductively coupled plasma mass spectrometry (GC/ICP-MS) coupled with solid phase micro-extraction can provide a simple, extremely selective and sensitive technique for the analysis of volatile sulfur and selenium compounds in the headspace of growing plants. In this work, the technique was used to evaluate the volatilization of selenium in wild-type and genetically-modified Brassica juncea seedlings. By converting toxic inorganic selenium in the soil to less toxic, volatile organic selenium, B. juncea might be useful in bioremediation of selenium contaminated soil.

ANALYSIS OF VOLATILE CONSTITUENTS OF CHINESE MEDICINAL HERBS BY FLASH DISTILLATION/CAPILLARY GAS CHROMATOGRAPHY/MASS SPECTROMETRY

In present work,the volatile constituents of Curcuma longa L.,A.lancea (Thunb.) DC.,Foeniculum vulgare Mill,and Cinnamomun cassia Presl.have been analyzed by flash distillation/capillary gas chro-matography/mass spectrometry.The results are consistent with those obtained by conventional steam distillation extraction method.The optimum condition of flash distillation has been studied.The experimental results showed that this new technique proved to be a simple,rapid and efficient tool for microanalysis of volatile constituents of Chinese medicinal herbs.

The Detection of THCA Using 2-Dimensional Gas Chromatography-Tandem Mass Spectrometry in Human Fingernail Clippings: Method Validation and Comparison with Head Hair

Marijuana use as well as abuse is a significant public health and public safety concern in the United States and using hair to identify marijuana users and abusers has been gaining acceptance in a number of venues including workplace, court ordered, and substance abuse treatment monitoring. After the presentation of a fully validated 2-dimensional gas chromatography-tandem mass spectrometry method for the detection of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCA), the chief metabolite of the main psychoactive compound in marijuana, Δ9-tetrahydrocannabinol (THC), we evaluated the usefulness of fingernail clippings as an alternative specimen type to hair by the analysis of a set of 60 matched pairs of head hair and fingernail clippings. The limit of detection was 10 fg/mg, the limit of quantitation was 20 fg/mg, and the assay was linear from 20 fg/mg to 500 fg/mg. The intra- and inter-assay imprecision and bias studies at 4 different concentrations (50, 100, 500, and 1000 fg/mg) were acceptable where all % Target observations were within 16% of their expected concentrations and all %CV calculations were less than 13.5%. THCA was detectable in more fingernail specimens (53.3%) than hair specimens (46.7%) and the mean concentrations in nails were on average 4.9 times higher than in hair (1813 fg/mg and 364 fg/mg, respectively). The THCA concentrations in hair and nail were strongly associated (r = 0.974, P < 0.01, n = 60) and the association was significant. The study demonstrated that fingernail clippings are a suitable alternative specimen type to hair to monitor for marijuana use and abuse.

Direct Determination of Polychlorinated-Biphenyls in Automotive Shredder Residues by Gas Chromatography-Mass Spectrometry

An easy and rapid method is proposed for the determination of PCBs in automotive shredder residues, using gas chromatography combined with low resolution mass spectrometry (GC-MS). It is based on direct n-hexane solid-liquid extraction, subtracting background of the lineal aliphatic hydrocarbon interferences and integration of chromatographic peaks containing selected ion PCBs masses (256, 292 and 326 m/z), which are common in all PCBs formulations. Recoveries were in the 80% - 120% range;PCBs were detected and quantified in shredder samples from an automotive shredder industry, thus indicating the validity of the method.

基于GC-IMS和GC-MS技术结合化学计量法分析干燥方式对香椿挥发性成分的影响

为研究干燥方式对香椿挥发性风味物质的影响,利用气相色谱-离子迁移谱技术(gaschromatography-ion mobility spectrometry,GC-IMS)和气相色谱-质谱联用技术(gas chromatography-mass spectrometry,GC-MS)、相对香气活性值(relative odor activity value,ROAV)对真空冷冻干燥、热泵干燥、热风干燥、微波真空干燥的香椿样品进行挥发性成分分析,并进一步结合化学计量方法主成分分析(principal component analysis,PCA)和偏最小二乘判别分析(partial least squares-discriminant analysis,PLS-DA),探究样品间挥发性成分的差异性。结果表明,通过GC-IMS检测到78个峰,鉴定出59种化合物。通过GC-MS鉴定出94种挥发性化合物,主要挥发性成分是硫化物、烯烃类和醛类。经过干燥后总挥发性化合物的含量显著降低。通过ROAV法确定了(E,Z)-二-1-丙烯基二硫化物、2-巯基-3,4-二甲基-2,3-二氢噻吩、正己醛、2-己烯醛、丁香酚等为香椿样品中关键香气化合物。PCA和PLS-DA结果表明,不同干燥方式的样品与新鲜样品有明显的分离,彼此之间也有明显的区别。鲜样和真空冷冻干燥样品为一组,其他3个干燥香椿样品为一组。根据变量投影重要性(variable importance in projection,VIP)得分共筛选出10种(VIP>1)标志挥发性化合物。干燥方式对香椿风味特性影响显著,真空冷冻干燥组与鲜样最为接近,考虑实际应用热泵干燥为香椿最适宜的脱水方式。本研究为热加工过程中风味品质控制提供一定的理论参考。

GC-MS结合电子鼻技术对不同茶区茉莉花茶香气的差异比较

为探究不同产区茉莉花茶香气差异,采用气相色谱-质谱(GasChromatography-Mass Spectrometry,GC-MS)结合电子鼻(Electronic Nose,E-nose)技术对西南、华南、江南三大茶区的8种茉莉花茶进行香气研究。结果表明,8个样品共鉴定出香气成分58种,其中西南、江南、华南茶区分别为45种、51种、47种。江南茶区香气化合物总量最高。共有香气成分主要包括邻氨基苯甲酸甲酯、顺式-3-己烯醇苯甲酸酯、乙酸苄酯、水杨酸甲酯、芳樟醇、吲哚等。其中水杨酸甲酯在江南茶区含量最高(22.32μg/g),分别较华南、西南茶区高33.96%、68.01%;邻氨基苯甲酸甲酯(67.39μg/g)和吲哚(43.84μg/g)含量在华南茶区最高。茉莉花茶香气评价指数(JasmineTea Flavor Index,JTF index)分析表明西南茶区样品等级最高。香气聚类分析将共有香气成分分为3类,分别呈花香、茉莉花香和草木香。通过电子鼻技术可知样品香气物质变化与硫化物、碳氢化合物、芳香化合物有关,并能有效区别样品香气。综上,三大茶区样品香气种类差异不明显,但各香气成分含量差异显著(P<0.05),江南和华南茶区的样品特征性香气成分含量较高,西南茶区样品综合指数高。

基于GC-MS和快速气相电子鼻对我国东北地区代表性粳米香气组分分析

为探究我国东北地区4种代表性粳米(香米五优稻4号、绥粳18和非香米龙粳31、盐丰47)香气组分差异,通过顶空-固相微萃取-气相色谱-质谱联用(HS-SPME-GC-MS)和快速气相电子鼻(Flash GC e-nose)技术对粳米香气组分进行鉴定。研究采用正交偏最小二乘法-判别分析(OPLS-DA)和层次聚类分析(HCA)等方法对4种粳米香气组分进行分析,结果表明,4种粳米的主要香气组分构成类似,以己醛、壬醛等醛类为主;五优稻4号主要香气成分含量显著(P≤0.05)高于其他3个品种粳米,使得其香气更加浓郁;关于粳米香气组分鉴定技术,GC-MS技术的准确度和检测范围优于电子鼻技术,而检测效率低于电子鼻技术。

基质溶剂校正结合高温离子源GC-MS/MS同时分析烟气中16种多环芳烃

本研究建立了高温离子源气相色谱-三重四极杆串联质谱(GC-MS/MS)法结合基质溶剂校正,使用样品萃取溶液直接进样,同时测定卷烟主流烟气中16种多环芳烃(PAHs)。考察了常温和高温离子源对目标物响应情况的影响,探究基质溶剂制备方法及基质效应对目标物定量结果的影响,分析市售不同圆周卷烟烟气的释放分布情况。结果表明,16种PAHs的定量工作曲线在各自线性范围内的相关系数R2为0.996 4~0.999 8,检出限为0.29~1.48 ng/支,定量限为0.95~4.94 ng/支,在低、中、高3个不同添加水平下的平均回收率为87.71%~123.26%,精密度为1.58%~9.45%。通过分析参比卷烟3R4F,该方法的检测结果与文献报道结果无明显差异。采用该方法检测市售58个品牌卷烟样品中的PAHs,总释放量为742.76~1 505.99 ng/支,并随卷烟焦油量减少而下降。该方法具有前处理简便,准确及重复性好的优点,适用于卷烟主流烟气中痕量PAHs的定量分析。

托里阿魏挥发油的GC-MS指纹图谱及抗宫颈癌作用研究

目的建立托里阿魏挥发油的气相色谱-质谱(GC-MS)指纹图谱,并考察托里阿魏挥发油的抗宫颈癌作用。方法采用有机溶剂提取法提取托里阿魏根的挥发油,并通过GC-MS鉴定所含成分。通过MTT比色法考察不同浓度托里阿魏挥发油对人宫颈癌Hela细胞增殖的抑制作用。采用Transwell法检测托里阿魏挥发油对人宫颈癌Hela细胞迁移、侵袭能力的影响。应用流式细胞术检测托里阿魏挥发油作用下的细胞凋亡率。结果托里阿魏挥发油中鉴别出58种化学成分,含量最多的是孕酮。托里阿魏挥发油对人宫颈癌Hela细胞的增殖有一定的抑制作用,IC50为55.21μg/ml。托里阿魏高、低剂量组与对照组相比,迁移和侵袭细胞数量显著减少(P<0.01)。结论托里阿魏挥发油中含量最高的是酮类化合物。托里阿魏提取物有一定的抗肿瘤作用。

基于HS-SPME/GC-MS/O分析滇绿茶特征香气物质

采用顶空固相微萃取结合气相色谱-质谱/嗅闻(HS-SPME/GC-MS/O)技术,对滇绿茶的香气物质进行定性、相对定量以及感官分析。将26个茶样根据产地分为四组,通过绿茶传统感官审评和香气定量描述性分析(QDA)筛选出3个品质突出的滇绿茶样品。HS-SPME/GC-MS/O分析结果表明:在上述3个样品中共鉴定出83种挥发性成分,总相对含量为10.694%,主要为醛、酮和芳香族化合物,对应的主要香气物质有22种。综合仪器分析和感官评价结果得出,香气强度最高的化合物有2,3-辛二酮(奶香)、月桂烯(柑橘香/花香)、(E,E)-2,4-庚二烯醛(花香)、苯甲醛(杏仁味)、芳樟醇(柑橘香/花香)、二氢芳樟醇(柠檬味/甜香)、香叶醇(玫瑰香/柑橘味)、柠檬烯(柑橘味)、香叶基丙酮(青草味)、二甲基硫醚(玉米香)、3-甲基丁醛(麦芽香)、6-甲基-5-庚烯-2-酮(爆米花香/烘烤香)、别罗勒烯(罗勒草香)、己醇(青草味/杏仁味)、水杨酸甲酯(清凉/薄荷味)、β-大马士酮(煮苹果味)、茉莉酮(花香)和β-紫罗兰酮(花香),上述化合物为滇绿茶特征香气成分。该研究为滇绿茶香气品质提升和工艺改进提供了理论基础。

干鲜连钱草茎叶挥发性成分的GC-MS分析

为探究干鲜连钱草不同部位中挥发性成分的差异,利用水蒸气蒸馏法分别提取干鲜连钱草茎叶中的挥发性成分,再运用气相色谱-质谱(gas chromatography-mass spectrometry,GC-MS)联用法,对提取的成分进行分析鉴定,最后运用主成分分析(principal component analysis,PCA)和聚类分析(cluster analysis,CA)分析其成分差异。由GC-MS数据分析可知,从连钱草干鲜茎叶提取的挥发性液体中共鉴定出125种成分,其中主要挥发性成分70种,包括醇类、羧酸类、酮类等。从鲜叶、鲜茎、干叶和干茎中分别鉴定出39、13、52、25种主要成分,相对含量分别占各组总挥发油的83.92%、97.21%、67.48%和98.29%,其中共有挥发性成分5种,各部位特有成分分别有13种、1种、16种和1种。分析结果表明,连钱草的鲜叶和干叶中挥发成分有显著差别,鲜茎和干茎中的挥发成分较为相似,但与鲜叶和干叶有较大区别。