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 ca...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.展开更多
采用顶空固相微萃取-全二维气相色谱-飞行时间质谱(headspace solid phase microextraction in combination with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry,HS-SPME-GC×GC-...采用顶空固相微萃取-全二维气相色谱-飞行时间质谱(headspace solid phase microextraction in combination with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry,HS-SPME-GC×GC-TOFMS)技术对全脂牛乳(whole milk,WM)、低脂牛乳(low-fat milk,LFM)和脱脂牛乳(non-fat milk,NFM)3种牛乳样品进行挥发性化合物分析,结果表明:共检测到49种挥发性化合物,其中2-壬酮、2-十一酮等奇数碳链的甲基酮构成WM的主要风味化合物;偏最小二乘法判别分析表明,其模型可以很好地区分3种牛乳样品,并且有较好的方差和交叉验证预测能力;通过变量投影重要性>1、P≤0.05且含量≥1%筛选出9种化合物,被认定为关键香气差异化合物,这些化合物可能是导致3种牛乳风味不同的主要因素;聚类热图结果表明,NFM因异味化合物(如十六醛)的存在可能导致不良感官表现,而WM和LFM存在更多的香气化合物,令其在感官方面具有饱满丰富的香气。本研究建立了HS-SPME-GC×GC-TOFMS分析牛乳的研究方法,为乳制品风味改进和乳制香精调配提供了理论指导。展开更多
Gene expression profile changes in brain regions following traumatic brain injury at the gene level cannot sufficiently elucidate gene expression time, expression amount, protein post-translational processing or modif...Gene expression profile changes in brain regions following traumatic brain injury at the gene level cannot sufficiently elucidate gene expression time, expression amount, protein post-translational processing or modification. Therefore, it is necessary to quantitatively analyze the gene expression profile using proteomic techniques. In the present study, we established a rat model of closed brain injury using Marmarou＇s weight-drop device, and investigated hippocampal differential protein expression using two-dimensional gel electrophoresis and surface-enhanced laser desorption ionization-time of flight-mass spectrometry. A total of 364 protein peaks were detected on weak cation exchange-2 protein chips, including 37 differential protein peaks. 345 protein peaks were detected on immobilized metal affinity capture arrays-Cu, including 12 differential protein peaks Further examination of these differential proteins revealed that glucose-regulated protein and proteasome subunit alpha type 3 expression were significantly upregulated post-injury. These results indicate that brain injury can alter protein expression in the hippocampus, and that glucose-regulated protein and proteasome subunit alpha type 3 are closely associated with the occurrence and development of traumatic brain injury.展开更多
A novel sample preparation method of matrix-assisted laser desorption/ionization mass spectrometry for polystyrene was reported. Compared to the conventional dried-droplet method, the efficiency of ionization and sign...A novel sample preparation method of matrix-assisted laser desorption/ionization mass spectrometry for polystyrene was reported. Compared to the conventional dried-droplet method, the efficiency of ionization and signal intensity of mass spectra were improved. The mechanism was also analyzed.展开更多
The degradation of the alkanolamine solvent used in the removal of acid gases from natural gas streams due to exposure to contaminants, thermal degradation and presence of oxygen or oxygen containing compounds will ch...The degradation of the alkanolamine solvent used in the removal of acid gases from natural gas streams due to exposure to contaminants, thermal degradation and presence of oxygen or oxygen containing compounds will change the solvent properties, such as heat transfer coefficient, diffusion coefficient, and mass transfer coefficient of the solvent. Therefore, characterization and quantification of amine degradation product becomes one of the important analyses to determine alkanolamine solvent’s health. In order to identify degradation products of alkanolamine solvent, analytical strategies by using mass spectrometry (MS) as detector have been studied extensively. In this work, due to the low concentration of the amine degradation product, a method was developed for identification of alkanolamine degradation products using LCMS-QTOF technique. A strategy for identification of trace degradation products has been identified. Six (6) alkanolamine degradation products had been identified by using LCMS-QTOF targeted analysis in the blended alkanolamine solvent used in natural gas processing plant. Another fifteen (15) molecular formulas having similarity in chemical structure to alkanolamine degradation products were identified using untargeted analysis strategy, as possible compounds related to degradation products. Using LCMS-QTOF via targeted and untargeted analysis strategy, without tedious column separation and reference standard, enables laboratory to provide a quick and indicative information for alkanolamine solvent’s organic degradation compounds identification in CO<sub>2</sub> adsorption, within reasonable analysis time.展开更多
The electron impact time-of-flight(TOF) mass spectra of the title compounds were studied to establish their fragmentation processes. With the high resolution of the TOF instrument, the exact mass for each fragment was...The electron impact time-of-flight(TOF) mass spectra of the title compounds were studied to establish their fragmentation processes. With the high resolution of the TOF instrument, the exact mass for each fragment was determined. These data were used to infer the molecular formulas and the elemental compositions for all the molecular ions and fragments through software interpretation. By further applying the fragmentation regularity, the majority of ions were fully assigned. The main fragmentation pathways of the title compounds include the formation of molecular ions by the loss of R 1 groups in the 4-position and the ester groups in the 5-position. The formed ion can be further fragmented by the elimination of MeOH.展开更多
The standards of plant toxins were separated by a C18 column with gradient elution with 0.1% formic acid/water (V/V) and 0.1% formic acid/acetonitrile (V/V) as mobile phase and acquired by ion mobility-quadrupole time...The standards of plant toxins were separated by a C18 column with gradient elution with 0.1% formic acid/water (V/V) and 0.1% formic acid/acetonitrile (V/V) as mobile phase and acquired by ion mobility-quadrupole time of flight mass spectrometry (IM-QTOF MS) in positive ion mode. A database of 308 plant toxins including retention time, collision cross-section (CCS) and its fragment ions was established. Honey dissolved in water or herbal beverage was extracted by acetonitrile and purified with PSA sorbent, and then acquired by ultrahigh-performance liquid chromatography IM-QTOFMS. The acquired data were processed by comparing with the database we established to confirm the target compounds. The average recoveries for samples at two levels ranged from 60.6% - 120.1%, with relative standard deviation (n = 6) less than 25%. The limit of quantitation for plant toxins ranged from 1 - 20 μg/kg. The developed screening method was used in determination of honey, herbal beverage and honey flavored tea beverage samples. The results showed that berberine was detected in one honey with 1 μg/kg and caffeine was present in some beverages with the concentration from 200 and 5500 μg/kg. This method could meet the requirement for rapid screening of plant toxins in honey and herbal beverage. It can be used for the quality control of honey and herbal beverage in enterprises or quality inspection departments. It also can be used in the rapid screening of food poisoning.展开更多
The time-of-flight mass spectrometry(TOF-MS),one of the mass spectrometry techniques,has been widely applied in the field of rapid screening of food hazard factors as a superior analysis technique because of its wide ...The time-of-flight mass spectrometry(TOF-MS),one of the mass spectrometry techniques,has been widely applied in the field of rapid screening of food hazard factors as a superior analysis technique because of its wide mass range,high resolution and mass measurement accuracy,high sensitivity and high analysis speed.In this paper,research progresses of TOF-MS on the detection of food additives,food contaminants and residues,illegal additives,pesticide residues,veterinary drug residues and mycotoxin were reviewed,and its probable approaching applications were prospected.展开更多
Matrix-assisted Laser Desorption/Ionization with Time-of-flight Mass Spectrometry (MALDI-TOFMS) was investigated as a method for the rapid identifica-tion of species. Current demand in microbial identi-fication is how...Matrix-assisted Laser Desorption/Ionization with Time-of-flight Mass Spectrometry (MALDI-TOFMS) was investigated as a method for the rapid identifica-tion of species. Current demand in microbial identi-fication is how to compare unknown strains to the known one quickly, semi-automatically and accurately. In this paper, we present a software tool that allows flexibly microbial matching in a user-friendly way, by letting the users to customize comparison parameters including: in vitro transcription enzyme, mass tolerance,minimum fragment length, intensity threshold and corresponding weights. We provide three spectral scoring functions to compute the affin-ity between the species. Therefore, the precision of microbial comparison increases. To test and verify this tool, we employed experimental spectral data based on MALDI-TOFMS and the gene sequences of E.coli and Salmonella. This software is written in Java for cross-platform intention.展开更多
基于顶空固相微萃取(head space solid phase microextraction,HS-SPME)结合全二维气相色谱-飞行时间质谱(comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry,GC×GC-TOFMS)建立了一种准确定量...基于顶空固相微萃取(head space solid phase microextraction,HS-SPME)结合全二维气相色谱-飞行时间质谱(comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry,GC×GC-TOFMS)建立了一种准确定量白酒中氨基甲酸乙酯(ethyl carbamate,EC)的方法。实验对HS-SPME方法进行了优化,在酒精度12%vol、加NaCl 3 g、萃取温度70℃,萃取时间40 min的条件下,能够显著提高目标物的响应值。实验以D_(5)-氨基甲酸乙酯(D_(5)-EC)为内标,对不同浓度的样品溶液进行GC×GC-TOFMS定量分析。结果表明,EC在10~500μg/L范围内线性关系良好,回归系数(R^(2))>0.998,检出限为0.19μg/L,定量限为0.64μg/L,平均回收率为97.57%,精密度为8.66%。测定结果与国标方法相比无显著性差异(P>0.05)。该方法前处理简单,检测灵敏度更高,为白酒中EC自动化定量测定提供了新思路。展开更多
基金funded by the Major State Basic Research Development Program of China(973 project,Grant No.2012CB214803)National Science and Technology Major Project of China(Grant No. 2016ZX05003-005)National Natural Science Foundation of China(Grant Nos.41322017 and 41472100)
文摘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.
文摘采用顶空固相微萃取-全二维气相色谱-飞行时间质谱(headspace solid phase microextraction in combination with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry,HS-SPME-GC×GC-TOFMS)技术对全脂牛乳(whole milk,WM)、低脂牛乳(low-fat milk,LFM)和脱脂牛乳(non-fat milk,NFM)3种牛乳样品进行挥发性化合物分析,结果表明:共检测到49种挥发性化合物,其中2-壬酮、2-十一酮等奇数碳链的甲基酮构成WM的主要风味化合物;偏最小二乘法判别分析表明,其模型可以很好地区分3种牛乳样品,并且有较好的方差和交叉验证预测能力;通过变量投影重要性>1、P≤0.05且含量≥1%筛选出9种化合物,被认定为关键香气差异化合物,这些化合物可能是导致3种牛乳风味不同的主要因素;聚类热图结果表明,NFM因异味化合物(如十六醛)的存在可能导致不良感官表现,而WM和LFM存在更多的香气化合物,令其在感官方面具有饱满丰富的香气。本研究建立了HS-SPME-GC×GC-TOFMS分析牛乳的研究方法,为乳制品风味改进和乳制香精调配提供了理论指导。
基金the National Natural Science Foundation of China,No. 30471934
文摘Gene expression profile changes in brain regions following traumatic brain injury at the gene level cannot sufficiently elucidate gene expression time, expression amount, protein post-translational processing or modification. Therefore, it is necessary to quantitatively analyze the gene expression profile using proteomic techniques. In the present study, we established a rat model of closed brain injury using Marmarou＇s weight-drop device, and investigated hippocampal differential protein expression using two-dimensional gel electrophoresis and surface-enhanced laser desorption ionization-time of flight-mass spectrometry. A total of 364 protein peaks were detected on weak cation exchange-2 protein chips, including 37 differential protein peaks. 345 protein peaks were detected on immobilized metal affinity capture arrays-Cu, including 12 differential protein peaks Further examination of these differential proteins revealed that glucose-regulated protein and proteasome subunit alpha type 3 expression were significantly upregulated post-injury. These results indicate that brain injury can alter protein expression in the hippocampus, and that glucose-regulated protein and proteasome subunit alpha type 3 are closely associated with the occurrence and development of traumatic brain injury.
文摘A novel sample preparation method of matrix-assisted laser desorption/ionization mass spectrometry for polystyrene was reported. Compared to the conventional dried-droplet method, the efficiency of ionization and signal intensity of mass spectra were improved. The mechanism was also analyzed.
文摘The degradation of the alkanolamine solvent used in the removal of acid gases from natural gas streams due to exposure to contaminants, thermal degradation and presence of oxygen or oxygen containing compounds will change the solvent properties, such as heat transfer coefficient, diffusion coefficient, and mass transfer coefficient of the solvent. Therefore, characterization and quantification of amine degradation product becomes one of the important analyses to determine alkanolamine solvent’s health. In order to identify degradation products of alkanolamine solvent, analytical strategies by using mass spectrometry (MS) as detector have been studied extensively. In this work, due to the low concentration of the amine degradation product, a method was developed for identification of alkanolamine degradation products using LCMS-QTOF technique. A strategy for identification of trace degradation products has been identified. Six (6) alkanolamine degradation products had been identified by using LCMS-QTOF targeted analysis in the blended alkanolamine solvent used in natural gas processing plant. Another fifteen (15) molecular formulas having similarity in chemical structure to alkanolamine degradation products were identified using untargeted analysis strategy, as possible compounds related to degradation products. Using LCMS-QTOF via targeted and untargeted analysis strategy, without tedious column separation and reference standard, enables laboratory to provide a quick and indicative information for alkanolamine solvent’s organic degradation compounds identification in CO<sub>2</sub> adsorption, within reasonable analysis time.
基金National Natural Science Foundation of China(No.2 0 332 0 2 0 )
文摘The electron impact time-of-flight(TOF) mass spectra of the title compounds were studied to establish their fragmentation processes. With the high resolution of the TOF instrument, the exact mass for each fragment was determined. These data were used to infer the molecular formulas and the elemental compositions for all the molecular ions and fragments through software interpretation. By further applying the fragmentation regularity, the majority of ions were fully assigned. The main fragmentation pathways of the title compounds include the formation of molecular ions by the loss of R 1 groups in the 4-position and the ester groups in the 5-position. The formed ion can be further fragmented by the elimination of MeOH.
文摘The standards of plant toxins were separated by a C18 column with gradient elution with 0.1% formic acid/water (V/V) and 0.1% formic acid/acetonitrile (V/V) as mobile phase and acquired by ion mobility-quadrupole time of flight mass spectrometry (IM-QTOF MS) in positive ion mode. A database of 308 plant toxins including retention time, collision cross-section (CCS) and its fragment ions was established. Honey dissolved in water or herbal beverage was extracted by acetonitrile and purified with PSA sorbent, and then acquired by ultrahigh-performance liquid chromatography IM-QTOFMS. The acquired data were processed by comparing with the database we established to confirm the target compounds. The average recoveries for samples at two levels ranged from 60.6% - 120.1%, with relative standard deviation (n = 6) less than 25%. The limit of quantitation for plant toxins ranged from 1 - 20 μg/kg. The developed screening method was used in determination of honey, herbal beverage and honey flavored tea beverage samples. The results showed that berberine was detected in one honey with 1 μg/kg and caffeine was present in some beverages with the concentration from 200 and 5500 μg/kg. This method could meet the requirement for rapid screening of plant toxins in honey and herbal beverage. It can be used for the quality control of honey and herbal beverage in enterprises or quality inspection departments. It also can be used in the rapid screening of food poisoning.
基金Supported by Phase II Modern Agricultural Industry Technology System Innovation Team Construction Project of Hebei Province(HBCT2018120207)Key R&D Projects of Hebei Province(19227516D)Tangshan Institute of Industrial Technology for Functional Agricultural Products(2019TY003b)。
文摘The time-of-flight mass spectrometry(TOF-MS),one of the mass spectrometry techniques,has been widely applied in the field of rapid screening of food hazard factors as a superior analysis technique because of its wide mass range,high resolution and mass measurement accuracy,high sensitivity and high analysis speed.In this paper,research progresses of TOF-MS on the detection of food additives,food contaminants and residues,illegal additives,pesticide residues,veterinary drug residues and mycotoxin were reviewed,and its probable approaching applications were prospected.
文摘Matrix-assisted Laser Desorption/Ionization with Time-of-flight Mass Spectrometry (MALDI-TOFMS) was investigated as a method for the rapid identifica-tion of species. Current demand in microbial identi-fication is how to compare unknown strains to the known one quickly, semi-automatically and accurately. In this paper, we present a software tool that allows flexibly microbial matching in a user-friendly way, by letting the users to customize comparison parameters including: in vitro transcription enzyme, mass tolerance,minimum fragment length, intensity threshold and corresponding weights. We provide three spectral scoring functions to compute the affin-ity between the species. Therefore, the precision of microbial comparison increases. To test and verify this tool, we employed experimental spectral data based on MALDI-TOFMS and the gene sequences of E.coli and Salmonella. This software is written in Java for cross-platform intention.
文摘基于顶空固相微萃取(head space solid phase microextraction,HS-SPME)结合全二维气相色谱-飞行时间质谱(comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry,GC×GC-TOFMS)建立了一种准确定量白酒中氨基甲酸乙酯(ethyl carbamate,EC)的方法。实验对HS-SPME方法进行了优化,在酒精度12%vol、加NaCl 3 g、萃取温度70℃,萃取时间40 min的条件下,能够显著提高目标物的响应值。实验以D_(5)-氨基甲酸乙酯(D_(5)-EC)为内标,对不同浓度的样品溶液进行GC×GC-TOFMS定量分析。结果表明,EC在10~500μg/L范围内线性关系良好,回归系数(R^(2))>0.998,检出限为0.19μg/L,定量限为0.64μg/L,平均回收率为97.57%,精密度为8.66%。测定结果与国标方法相比无显著性差异(P>0.05)。该方法前处理简单,检测灵敏度更高,为白酒中EC自动化定量测定提供了新思路。
