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1.
The determination of organic sulfur compounds (OSC) in coal is of great interest. Technically and operationally these compounds
are not easily removed and promote corrosion of equipment. Environmentally, the burning of sulfur compounds leads to the emission
of SO
x
gases, which are major contributors to acid rain. Health-wise, it is well known that these compounds have mutagenic and carcinogenic
properties. Bitumen can be extracted from coal by different techniques, and use of gas chromatography coupled to mass spectrometric
detection enables identification of compounds present in coal extracts. The OSC from three different bitumens were tentatively
identified by use of three different extraction techniques: accelerated solvent extraction (ASE), ultrasonic extraction (UE),
and supercritical-fluid extraction (SFE). Results obtained from one-dimensional gas chromatography (1D GC) coupled to quadrupole
mass spectrometric detection (GC–qMS) and from two-dimensional gas chromatography with time-of-flight mass spectrometric detection
(GC × GC–TOFMS) were compared. By use of 2D GC, a greater number of OSC were found in ASE bitumen than in SFE and UE bitumens.
No OSC were identified with 1D GC–qMS, although some benzothiophenes and dibenzothiophenes were detected by use of EIM and
SIM modes. GC × GC–TOFMS applied to investigation of OSC in bitumens resulted in analytical improvement, as more OSC classes
and compounds were identified (thiols, sulfides, thiophenes, naphthothiophenes, benzothiophenes, and benzonaphthothiophenes).
The roof-tile effect was observed for OSC and PAH in all bitumens. Several co-elutions among analytes and with matrix interferents
were solved by use of GC×GC. 相似文献
2.
A previously constructed semi-rotating cryogenic modulator was modified for comprehensive two-dimensional gas chromatography
(GC×GC). The retention time repeatability was improved by replacing the modulator control program unit with a new system.
Peak widths obtained with the modified modulator were comparable with those obtained with the previous modulator and other
modulator types. The modulator was easy to construct and it can be installed in any commercial GC system. The constructed
GC×GC–FID system and data obtained by gas chromatography–mass spectrometry (GC–MS) were used for identification of unknowns
in forest aerosol samples.
Figure A semi-rotating cryogenic modulator in which modulation is based on two-step cryogenic trapping with continuously flowing
carbon dioxide has been developed for comprehensive two-dimensional gas chromatography 相似文献
3.
This work presents the validation study of the comprehensive two-dimensional gas chromatography (GC×GC)–time-of-flight mass
spectrometry method performance in the analysis of the key World Anti-Doping Agency (WADA) anabolic agents in doping control.
The relative abundance ratio, retention time, identification and other method performance criteria have been tested in the
GC×GC format to confirm that they comply with those set by WADA. Furthermore, tens of other components were identified with
an average similarity of >920 (on the 0–999 scale), including 10 other endogenous sterols, and full mass spectra of 5,000+
compounds were retained. The testosterone/epitestosterone ratio was obtained from the same run. A new dimension in doping
analysis has been implemented by addressing separation improvement. Instead of increasing the method sensitivity, which is
accompanied by making the detector increasingly “blind” to the matrix (as represented by selected ion monitoring mode, high-resolution
mass spectrometry (MS) and tandem MS), the method capabilities have been improved by adding a new “separation” dimension while
retaining full mass spectral scan information. Apart from the requirement for the mass spectral domain that a minimum of three
diagnostic ions with relative abundance of 5% or higher in the MS spectra, all other WADA criteria are satisfied by GC×GC
operation. The minimum of three diagnostic ions arises from the need to add some degree of specificity to the acquired mass
spectrometry data; however, under the proposed full MS scan method, the high MS similarity to the reference compounds offers
more than the required three diagnostic ions for an unambiguous identification. This should be viewed as an extension of the
present criteria to a full-scan MS method. 相似文献
4.
We designed and operated a new system of pulsed flow modulation (PFM) two dimensional comprehensive gas chromatography (GC × GC) mass spectrometry (MS). This system is based on the combination of PFM–GC × GC with a quadrupole mass spectrometer of GC–MS via a supersonic molecular beams interface and its fly-through Cold EI ion source and applied this system for the analysis of JP8 jet fuel. PFM is a simple GC × GC modulator that does not consume cryogenic gases while providing tunable second GC × GC column injection time for enabling the use of quadrupole based mass spectrometry regardless its limited scanning speed. We analyzed JP8 jet fuel with our new PFM–GC × GC–MS with Cold EI system and found that as the second dimension GC elution time is increased the observed molecular ion mass is reduced. This unique observation that helped in improved sample compounds identification under co-elution conditions was enabled via having abundant molecular ions in Cold EI for all the fuel compounds. We named this type of analysis as PFM–GC × GC × MS. We found and discuss in this paper that PFM–GC × GC–MS with Cold EI combines improved separation of GC × GC with Cold EI benefits of tailing-free ultra-fast ion source response time and enhanced molecular ions and mass spectral isomer and isotope information for the provision of increased sample identification information. 相似文献
5.
Two methods were developed for the quantitative analysis of phenolic acids in herb extracts. The methods were based on liquid
chromatography–time-of-flight mass spectrometry (LC–TOFMS) and gas chromatography–mass spectrometry (GC–MS). The methods were
compared in terms of their linearity, repeatability, selectivity, sensitivity and the speed of the analysis. The sensitivity
was good for both methods, with limits of detection of <80 ng/ml for most of the compounds. The relative standard deviations
(RSD) of the peak areas were on average 7.2% for the LC–TOFMS method and 1.4% for the GC–MS method. Both methods were found
to be suitable for the determination of the target analytes, although GC–MS was better suited to the quantitative determination
of compounds present at low concentrations. 相似文献
6.
The ethyl acetate-based multi-residue method for determination of pesticide residues in produce has been modified for gas
chromatographic (GC) analysis by implementation of dispersive solid-phase extraction (using primary–secondary amine and graphitized
carbon black) and large-volume (20 μL) injection. The same extract, before clean-up and after a change of solvent, was also
analyzed by liquid chromatography with tandem mass spectrometry (LC–MS–MS). All aspects related to sample preparation were
re-assessed with regard to ease and speed of the analysis. The principle of the extraction procedure (solvent, salt) was not
changed, to avoid the possibility invalidating data acquired over past decades. The modifications were made with techniques
currently commonly applied in routine laboratories, GC–MS and LC–MS–MS, in mind. The modified method enables processing (from
homogenization until final extracts for both GC and LC) of 30 samples per eight hours per person. Limits of quantification
(LOQs) of 0.01 mg kg −1 were achieved with both GC–MS (full-scan acquisition, 10 mg matrix equivalent injected) and LC–MS–MS (2 mg injected) for
most of the pesticides. Validation data for 341 pesticides and degradation products are presented. A compilation of analytical
quality-control data for pesticides routinely analyzed by GC–MS (135 compounds) and LC–MS–MS (136 compounds) in over 100 different
matrices, obtained over a period of 15 months, are also presented and discussed. At the 0.05 mg kg −1 level acceptable recoveries were obtained for 93% (GC–MS) and 92% (LC–MS–MS) of pesticide–matrix combinations. 相似文献
7.
A sensitive method has been developed and validated for the determination of diverse groups of pharmaceuticals, steroid hormones,
and hormone-like personal care products in sewage sludge. Samples were extracted by ultrasonic-assisted extraction followed
by solid-phase extraction cleanup. For determination of estrogens and hormone-like phenolic compounds, sample extracts were
further derivatized with dansyl chloride and purified with silica gel column chromatography to improve the analytical sensitivity.
The chemicals were determined by ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS) in multiple-reaction
monitoring mode. Recoveries ranged mostly from 63% to 119% with relative standard deviations within 15%. Method quantification
limits were 0.1–3 ng g −1 dry weight (dw) for sewage sludge. The method was applied to a preliminary investigation of pharmaceuticals and personal
care products (PPCPs) in sewage sludge and sediment in the Pearl River Delta, South China. Triclosan, triclocarban, 2-phenylphenol,
bisphenol A, and parabens were ubiquitously detected at 3.6–5088.2 ng g −1 dw in sludge and 0.29–113.1 ng g −1 dw in sediment samples, respectively. Estrone, carbamazepine, metoprolol, and propranolol were also frequently quantified
in the sludge and sediment samples. The dewatering process caused no significant losses of these PPCPs in sewage sludge. 相似文献
8.
There is a need for cost-efficient alternatives to gas chromatography (GC)–high-resolution mass spectrometry (HRMS) for the
analysis of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs) in food and feed. Comprehensive two-dimensional
GC–micro electron capture detection (GC×GC-μECD) was tested and all relevant (according to the World Health Organisation,
WHO) PCDD/Fs and PCBs could be separated when using a DB-XLB/LC-50 column combination. Validation tests by two laboratories
showed that detectability, repeatability, reproducibility and accuracy of GC×GC-μECD are all statistically consistent with
GC-HRMS results. A limit of detection of 0.5 pg WHO PCDD/F tetrachlorodibenzo- p-dioxin equivalency concentration per gram of fish oil was established. The reproducibility was less than 10%, which is below
the recommended EU value for reference methods (less than 15%). Injections of vegetable oil extracts spiked with PCBs, polychlorinated
naphthalenes and diphenyl ethers at concentrations of 200 ng/g showed no significant impact on the dioxin results, confirming
in that way the robustness of the method. The use of GC×GC-μECD as a routine method for food and feed analysis is therefore
recommended. However, the data evaluation of low dioxin concentrations is still laborious owing to the need for manual integration.
This makes the overall analysis costs higher than those of GC-HRMS. Further developments of software are needed (and expected)
to reduce the data evaluation time. Combination of the current method with pressurised liquid extraction with in-cell cleanup
will result in further reduction of analysis costs.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
9.
One- and comprehensive two-dimensional gas chromatography were hyphenated with soft photoionization mass spectrometry. The
characteristics of these two- and three-dimensional comprehensive separation techniques are discussed in detail. Using the
innovative electron beam pumped excimer light source (EBEL) for single-photon ionization (SPI), organic molecules with ionization
energies ( E
i
) of below 9.8 eV can be detected by a time-of-flight mass spectrometer (TOF-MS). SPI with 126 nm vacuum ultraviolet (VUV)
photons enables the universal and soft ionization of organic molecules. SPI-TOF-MS hyphenated to one-dimensional gas chromatography
results in a comprehensive two-dimensional separation method (GC×MS). To demonstrate this, diesel fuel was analyzed, and the
resulting GC×MS chromatograms are discussed in depth. A three-dimensional separation method was also realized by combining
comprehensive two-dimensional gas chromatography (GC×GC) with SPI-MS. In the resulting separation space, constituents originating
from mineral oil diesel blended with biodiesel were dispersed along the two GC separation axes, while the molecular mass axis
served as a third separation dimension. 相似文献
10.
The analysis of volatile organic compounds in samples of biological fluids characterized by complex matrices is highly challenging.
This paper presents a comparison of the results obtained in this field using three solvent-free techniques: thin-layer headspace
with autogenous generation of liquid sorbent (TLHS) and membrane separation of the trace substances (pervaporation, PV), both
of which are coupled to direct aqueous injection gas chromatography–electron capture detection (TLHS–DAI–GC–ECD and PV–DAI–GC–ECD),
as well as conventional static headspace analysis followed by GC analysis with ECD detection (HS–GC–ECD). Basic validation
parameters of the HS–GC–ECD, TLHS–DAI–GC–ECD and PV–DAI–GC–ECD procedures were calculated for water and urine samples. The
calibration curves for all procedures were linear within the concentration range examined. The intermediate precisions of
the procedures were good and reached about 10% (for all analytes) for HS–GC–ECD and TLHS–DAI–GC–ECD. The poorest results were
obtained for PV–DAI–GC–ECD: about 20% for all analytes. The lowest method detection limits were obtained for the TLHS–DAI–GC–ECD
procedure: below 0.0022 μg/L for all analytes. The enrichment factors did not differ significantly between water and urine
samples, indicating little or no matrix effect in all procedures. 相似文献
11.
Compared to conventional one-dimensional gas chromatography (1D-GC), comprehensive two-dimensional gas chromatography (GC×GC)
offers increased peak capacity, improved resolution and enhanced mass sensitivity. In addition, it generates structured two-dimensional
(2-D) chromatograms, which aids in the identification of compound classes. Sample preparation procedures can often be minimized,
or even eliminated in some cases, due to the superior separating power offered by the technique. All of these advantages make
GC×GC a very powerful tool in environmental analysis involving the determination of trace levels of toxic compounds in complex
matrices. This review paper summarizes and examines the historical and recent GC×GC applications in environmental analysis
and monitoring. 相似文献
12.
采用全二维气相色谱-飞行时间质谱(GC×GC-TOF MS)对催化裂化汽油全馏分进行了定性与定量分析,建立了相应的分析方法.结果表明,汽油族组成中的烷烃、烯烃、环烷烃、芳烃在全二维点阵谱图中呈分区域、带状的分布特点.GC×GC-TOF MS根据催化裂化汽油组分内分子的沸点及极性差异对其进行两个维度分离,极大地避免了普通色谱法分析过程中沸点相似化合物共流的弊端,实现催化裂化汽油组分的精确分离和准确定性分析.通过引入响应因子,修正了不同性质的烃类在电离源上电离效率的差异,使得TOF对催化裂化汽油族组成的定量结果与普通气相色谱法的定量结果的相关性较好,且应用GC×GC-TOF MS方法获得了催化裂化汽油更为精确的族组成信息.GC×GC-TOF MS为催化裂化汽油精确表征提供了一种有效方法. 相似文献
13.
One of the major objectives in metabolomics is the identification of subtle changes in metabolite profiles as affected by
genetic or environmental factors. Comprehensive two-dimensional gas chromatography (GC × GC) hyphenated to a fast-acquisition
mass spectrometer is a well-established analytical technique to study the composition of complex samples due to its enhanced
separation capacity, sensitivity, peak resolution, and reproducibility. This review reports applications of GC × GC to metabolomics
studies of sample of different types (biofluid, cells, tissue, bacteria, yeast, plants), and discusses its advantages and
limitations. 相似文献
14.
The significance of forensic arson analysis accelerates the applications of new technologies in this area. Based on the previously
reported application of differential mobility spectrometry (DMS) as a detection method for gas chromatography (GC) in arson
analysis, the performances of DMS and mass spectrometry (MS) were compared using a novel chemometric tool, projected difference
resolutions (PDRs). The PDR results show that one-way mass spectra data exhibit higher resolution than DMS data, while total
ion chromatograms from GC–DMS show higher resolution than that from GC/MS for differentiating seven kinds of ignitable liquids.
Combining the information from both chromatography and spectra, two-way data always have higher resolution than one-way data
for these two detection methods, and GC/MS would exhibit better performance than GC–DMS according to the minimum resolution
value. To verify the PDR results, a fuzzy rule-building expert system was applied for classifying these seven kinds of ignitable
liquids from fire debris based on GC–DMS and GC/MS data, respectively. The prediction accuracies were consistent with PDR
results, which proved that PDR is a powerful tool in comparing the performances of different analysis methods for pattern
recognition.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
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. 相似文献
16.
Comprehensive gas chromatography (GC) has emerged in recent years as the technique of choice for the analysis of volatile and semivolatile compounds in complex matrices. Coupling it with high‐resolution mass spectrometry (MS) makes a powerful tool for identification and quantification of organic compounds. The results obtained in this study showed a significant improvement by using GC×GC‐EI‐MS in comparison with GC‐EI‐MS; the separation of chromatogram peaks was highly improved, which facilitated detection and identification. However, the limitation of Orbitrap mass analyzer compared with time‐of‐flight analyzer is the data acquisition rate; the frequency average was about 25 Hz at a mass resolving power of 15.000, which is barely sufficient for the proper reconstruction of the narrowest chromatographic peaks. On the other hand, the different spectra obtained in this study showed an average mass accuracy of about 1 ppm. Within this average mass accuracy, some reasonable elemental compositions can be proposed and combined with characteristic fragment ions, and the molecules can be identified with precision. At a mass resolving power of 7.500, the scan rate reaches 43 Hz and the GC×GC‐MS peaks can be represented by more than 10 data points, which should be sufficient for quantification. The GC×GC‐MS was also applied to analyze a cellulose bio‐oil sample. Following this, a highly resolved chromatogram was obtained, allowing EI mass spectra containing molecular and fragment ions of many distinct molecules present in the sample to be identified. 相似文献
17.
A new electro solid-phase microextraction (El-SPME) technique using homemade pencil-lead fibers has been developed as an effective
means of selective extraction of methamphetamine before analysis by gas chromatography (GC) and gas chromatography–mass spectrometry
(GC–MS). The methamphetamine was extracted by use of a laboratory-made El-SPME cell with three electrodes—the pencil-lead
SPME fiber, Ag/AgCl, and platinum as working, reference, and auxiliary electrodes, respectively. A negative potential was
applied to the homemade pencil-lead fiber during extraction. Experimental conditions, for example type of pencil-lead fiber,
conditions for modification of the fiber, extraction time, applied potential, pH, and gas chromatographic conditions were
optimized. Methamphetamine was identified by GC–MS. Screening of the extracted compounds showed that the proposed El-SPME
technique is much more selective than direct SPME using a commercially available polyacrylate fiber. Under the optimum conditions
the calibration plot for the compound was linear in the range 50–3,200 ng mL −1 and the detection limit was 34 ng mL −1. 相似文献
18.
Phytosterol oxidation products (POPs) have been suggested to exert adverse biological effects similar to, although less severe
than, their cholesterol counterparts. For that reason, their analysis in human plasma is highly relevant. Comprehensive two-dimensional
gas chromatography (GC×GC) coupled with time-of-flight mass spectrometry (TOF-MS) has been proven to be an extremely powerful
separation technique for the analysis of very low levels of target compounds in complex mixtures including human plasma. Thus,
a GC×GC/TOF-MS method was developed and successfully validated for the simultaneous quantification of ten POPs in human plasma.
The calibration curves for each compound showed correlation coefficients ( R
2) better than 0.99. The detection limits were below 0.1 ng mL −1. The recovery data were between 71.0% and 98.6% (RSDs <10% for all compounds validated). Good results were obtained for within-
and between-day repeatability, with most values being below 10%. In addition, non-targeted sterol metabolites were also identified
with the method. The concentrations of POPs found in human plasma in the current study are between 0.3 and 4.5 ng mL −1, i.e., 10–100 times lower than the typical values found for cholesterol oxidation products. 相似文献
19.
In this review, we consider and discuss the affinity and complementarity between a generic sample preparation technique and the comprehensive two‐dimensional gas chromatography process. From the initial technical development focus (e.g., on the GC×GC and solid‐phase microextraction techniques), the trend is inevitably shifting toward more applied challenges, and therefore, the preparation of the sample should be carefully considered in any GC×GC separation for an overreaching research. We highlight recent biomedical, food, and plant applications (2016–July 2020), and specifically those in which the combination of tailored sample preparation methods and GC×GC–MS has proven to be beneficial in the challenging aspects of non‐targeted analysis. Specifically on the sample preparation, we report on gas‐phase, solid‐phase, and liquid‐phase extractions, and derivatization procedures that have been used to extract and prepare volatile and semi‐volatile metabolites for the successive GC×GC analysis. Moreover, we also present a milestone section reporting the early works that pioneered the combination of sample preparation techniques with GC×GC for non‐targeted analysis. 相似文献
20.
An efficient microwave-assisted extraction (MAE) procedure coupled to gas chromatography–mass spectrometry (GC–MS) with electron
impact (EI) and chemical ionization (CI) has been developed to determine five organophosphate flame retardants (OPFRs) in
marine and river sediments. The effects of various operating parameters on the quantitative extraction of the OPFRs through
MAE were systematically investigated. Selected OPFRs were extracted from the sediments through MAE using 40 mL of acetone
at 120 °C for 20 min. The limits of quantitation ranged from 0.1 to 0.4 ng/g (dry weight) in 2 g of the sediment samples.
Moreover, as the chlorinated alkyl phosphates present no molecular ions in EI, GC–MS with furan-CI (furan-CI) was applied
to confirm their determination in complex environmental samples. The recoveries of the selected OPFRs in spiked sediment samples
ranged from 62% to 106% (relative standard derivation, 1−11%). The total concentrations of the selected OPFR residues in marine
and river sediments ranged from 1.0 to 12.6 ng/g. 相似文献
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