裂解气相色谱-质谱法鉴别汽车用非金属材料

建立了裂解气相色谱-质谱联用法(PY-GCMS)测试汽车用非金属材料,包括其中主体材料及有机添加剂的定性分析。首先将样品进行逸出气体分析(EGA),然后根据是分析非金属材料中的添加剂还是主体材料来选择合适的裂解温度,进行裂解气相色谱-质谱分析。试验结果表明,不同材料可根据裂解后的特征峰及所使用的添加剂进行鉴别。该方法无需样品前处理,样品用量少,是一种快速鉴别和测定汽车用聚合物材料的有效方法。     

裂解气相色谱-质谱联用法分析聚醚酰亚胺的裂解产物

应用裂解气相色谱及质谱联用法研究了3种聚醚酰亚胺(PEIM′s)的裂解行为,并根据裂解产物的结构及其相对产率推断了裂解的机理。取3种PEIM样品置于石英裂解管中,分别在550℃,650℃,750℃条件下裂解,所得产物用气相色谱-质谱联用法分析。分析中采用DB-5毛细管色谱柱,电子轰击离子源(200℃,70eV)及在m/z 29～500范围内全扫描方式,并用NIST谱库进行检索和用归一化法计算峰面积进行定量。由试验结果可知:选择在750℃进行裂解较好,在此条件下获得主要裂解产物存在的更明显的信息,有利于对产物进行详细分析和鉴定。     

PGC-MS鉴别乙烯-辛烯共聚物

乙烯-辛烯共聚物与聚乙烯性能、价格差别很大,但无鉴别二者的检验方法。我们采用裂解气相色谱一质谱(PGC-MS)方法研究这两种聚合物的热裂解产物的组成,发现两者裂解产物的成分相同,均为不同碳数的烷烃、烯烃化合物;但含量有区别,主要区别在辛烯。乙烯-辛烯共聚物裂解产物中辛烯(C8)的相对含量明显高于聚乙烯,C8峰可作为鉴别乙烯-辛烯共聚物的特征峰,据此建立了鉴别两种聚合物的方法,并在进出口商品检验中得到很好的应用。     

裂解色谱法研究渣油中硫化物的结构及组成特征

采用裂解气相色谱(PY-GC)方法研究重油中的大分子硫化物。实验考察了裂解时间和裂解温度对裂解反应的影响,在此基础上确定了裂解色谱条件,并分析了渣油裂解产物的组成。通过对大港、俄罗斯、前郭、孤岛及俄罗斯-大庆混合减压渣油等5种渣油的裂解实验,发现不同来源的渣油裂解产物中硫化物的组成和含量存在较大差异。实验中所得到的裂解产物中硫化物的组成为渣油中硫化物的组成提供了重要信息。     

裂解气相色谱/质谱法检验复印墨粉

复印墨粉检验分析在经济案件侦查以及墨粉配方研究方面具有十分重要的意义。采用裂解气相色谱技术,对收集到的复印墨粉进行分离分析,并用裂解气相色谱/质谱联用技术,对所得裂解峰进行归属。分析结果的重复性与稳定性良好,复印件上墨粉与原墨粉分析结果一致。对不同厂家与牌号的墨粉进行区分与归类,为墨粉鉴别提供了依据。     

不同涤纶绳索纤维的PY-GC/MS定性分析

利用裂解-气相色谱/质谱联用法对9个不同产地、不同规格的涤纶绳索样品进行鉴别分析.首先通过优化选择,确定试验条件,即裂解温度为550℃、裂解时间为6 s时,柱程序升温条件为50℃(1 min)20℃/min→250℃(10 min).在此条件下可最大限度的显示涤纶裂解产物的特征.9个样品的裂解分析结果显示,涤纶的主要裂解产物有13种,其中特征裂解产物为苯甲酸(相对强度100%)、苯甲酸乙烯酯、联苯、苯等.虽然9个涤纶绳索有相同的裂解特征,但个别裂解产物及各特征裂解产物的相对含量有所不同.这一差异可以作为不同规格、不同产地涤纶绳索分析鉴别的依据.     

石英砂固体分散剂制样的裂解气相色谱法测定涤/毛纤维混纺比列

基于纵型微型炉裂解器的裂解气相色谱法(Py-GC)建立了涤/毛纤维混纺比例的测定方法。以石英砂为固体质量分散剂,将样品加入其中碾磨成粉末后称量进样,在550℃的裂解温度下得到相应的裂解色谱图,依据各自特征裂解谱图与释放气体分析曲线可识别涤纶与羊毛纤维;选择涤/毛二元混纺纤维裂解谱图上涤纶的特征裂解产物——联苯为定量峰,计算混纺纤维中涤纶的质量百分含量,进而推算出羊毛纤维的含量。样品和石英砂的最佳配比为0.02 g∶4 g,涤纶质量在0.0256~0.2048 mg范围内联苯的线性良好,相关系数R2=0.9952。对不同涤/毛混纺比例的实际样品进行了测定,相对标准偏差RSD<3%(n=3);本法与国标法所得结果的偏差小于5%。结果表明,本方法简便、准确,适合涤/毛二元混纺纤维混纺比例的质控分析。     

沙门氏菌全细胞的热裂解气相色谱-质谱分析

本研究探讨了一种新型的快速检测食源性病原菌的方法。该方法应用热裂解气相色谱-质谱技术(pyrolysis-gas chromatography-mass spectrometry,Py-GC-MS)对食源性致病菌沙门氏菌进行了分析。通过对影响总离子流色谱图条件(热裂解条件、色谱条件、质谱条件)的研究,得到了满意的实验结果。结果表明:沙门氏菌全细胞在裂解温度600℃,时间为10s,离子源温度220℃,电离方式为EI,电离能为60eV的条件下可得到清晰的总离子流色谱图,同时对部分裂解产物的结构进行了鉴定。该方法快速、简便,可为研究快速鉴定致病菌提供新的技术手段。     

低分子有机物的裂解色谱定性

裂解色谱多用于不挥发的合成、天然和生物高分子物质的分析和鉴别,裂解色谱一质谱联用也已用于气相分子裂解反应的研究[1+3],裂解色谱作为低分子有机物的定性方法尚未见报导。本文作出了15类同系物数+种化合物的裂解色谱图,发现低分子有机物在一定的裂解色谱条件下有确定的指纹图,可以作为一种新的定性方法。本方法灵敏度高、设备简单。     

气单胞菌RD2及其质粒消除菌和接合子的裂解气相色谱研究

以热裂解产物为分类鉴定依据的裂解气相色谱法是鉴定、鉴别高分子化合物的一种色谱技术。自Oyama用裂解气相色谱法研究微生物细胞以来,随着仪器的不断改进和完善,国内外学者已将其应用到更为广泛的研究领域。事实证明,裂解气相色谱法用于生物材料的鉴定、鉴别和分析也将成为一种灵敏、准确、重现性高的快速方法,本文对RD_2脱色菌及其质粒消除菌     

Solid Phase Micro-extraction – Gas Chromatography–Mass Spectrometry to Characterize Pyrolysis Products from Textiles

Headspace solid phase micro-extraction gas chromatography–mass spectrometry (HS-SPME GC–MS) was used for identifying thermally labile volatile compounds from cotton, wool, polyester, olefin, silk, and acrylic. Volatile compounds were generated from the textiles using a pyrolysis apparatus prior to GC–MS. Pyrolysis temperatures ranged from 190 to 550°C. Each textile displayed a unique chromatogram containing compounds that were consistent with the chemical structure of the textile. Experimental parameters that were investigated included the temperature, sample size, and sampling time to determine their effect on the number and intensity of peaks in the chromatograms as well as to identify optimum conditions for analysis. Heating of each sample was achieved using a resistively heated Pt wire. Full pyrolysis at 550°C of the textiles appeared to give the best results in terms of peak height relative to background. A range of sample sizes (0.02–1.5?mg) were used and, generally, ≤0.02?mg was used for identifying the textiles. The reproducibility of retention times for selected compounds in the chromatograms was less than 1% relative standard deviation. The combination with mass spectrometry provided valuable structural information.     

Application of off-line pyrolysis with dynamic solid-phase microextraction to the GC–MS analysis of biomass pyrolysis products

Pyrolysis coupled with dynamic solid-phase micro extraction (Py-SPME) followed by GC–MS analysis was applied to the determination of volatile compounds evolved by a micro-scale off-line pyrolysis apparatus, in order to extend the information affordable with this type of analytical equipment. The Py-SPME method with a carboxen/PDMS fiber working in the retracted mode was tested on four biomass samples (switchgrass, sweet sorghum, corn stalk and poplar) for qualitative analysis of semi-volatile pyrolysis products and quantitative determination of main volatiles (C₁–C₄) pyrolysis products. The developed procedure allowed capturing and analysis of all GC analyzable compounds, without memory effects and with good peak resolution also for early GC-eluting compounds. Twelve main volatile pyrolysis products, including hydroxyacetaldehyde and acetic acid, were successfully quantified; in spite of the intrinsic variability introduced by dynamic SPME sampling, results were relatively accurate and consistent with literature data on bench pyrolysis reactors.     

An Improved Capillary Gas Chromatography Method for Triethylamine. Application to Sarafloxacin Hydrochloride and GnRH Residual Solvents Testing

ABSTRACT

A capillary gas chromatography (GC) method for residual solvents in the veterinary antibacterial compound sarafloxacin hydrochloride included triethylamine (TEA). Despite the use of commercially available deactivated columns and inlet liners, the peak shape and reproducibility for the TEA peak were very poor. The use of glass inlet liners and glass wool which were treated with methanolic potassium hydroxide resulted in marked improvement for TEA. This method was also used to determine residual TEA in the polypeptide GnRH.     

Qualitative and quantitative analysis of pyrolysis oil by gas chromatography with flame ionization detection and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry

Pyrolysis oils have attracted a lot of interest, as they are liquid energy carriers and general sources of chemicals. In this work, gas chromatography with flame ionization detector (GC-FID) and two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS) techniques were used to provide both qualitative and quantitative results of the analysis of three different pyrolysis oils. The chromatographic methods and parameters were optimized and solvent choice and separation restrictions are discussed. Pyrolysis oil samples were diluted in suitable organic solvent and were analyzed by GC×GC-TOFMS. An average of 300 compounds were detected and identified in all three samples using the ChromaToF (Leco) software. The deconvoluted spectra were compared with the NIST software library for correct matching. Group type classification was performed by use of the ChromaToF software. The quantification of 11 selected compounds was performed by means of a multiple-point external calibration curve. Afterwards, the pyrolysis oils were extracted with water, and the aqueous phase was analyzed both by GC-FID and, after proper change of solvent, by GC×GC-TOFMS. As previously, the selected compounds were quantified by both techniques, by means of multiple point external calibration curves. The parameters of the calibration curves were calculated by weighted linear regression analysis. The limit of detection, limit of quantitation and linearity range for each standard compound with each method are presented. The potency of GC×GC-TOFMS for an efficient mapping of the pyrolysis oil is undisputable, and the possibility of using it for quantification as well has been demonstrated. On the other hand, the GC-FID analysis provides reliable results that allow for a rapid screening of the pyrolysis oil. To the best of our knowledge, very few papers have been reported with quantification attempts on pyrolysis oil samples using GC×GC-TOFMS most of which make use of the internal standard method. This work provides the ground for further analysis of pyrolysis oils of diverse sources for a rational design of both their production and utilization process.     

Universal and discriminative detection using a miniaturized pulsed discharge detector in comprehensive two-dimensional GC

A miniaturized pulsed discharge detector (Mini-PDD) has been successfully demonstrated for comprehensive 2-D GC (GC x GC) analysis of pyrolysis gasoline and the pyrolysis GC x GC analysis of a polyethylene copolymer. The detector cell volume of the Mini-PDD is reduced to 25% of the Valco plug-in PDD D-3. An n-C11 peak width at base is 96 ms for the Mini-PDD, about 23% larger than a peak width of 78 ms detected by a flame ionization detector (FID). The Mini-PDD has sufficient response time for most GC x GC applications. When Mini-PDD is operated in helium photoionization mode (Mini He-PDD), it is a universal detector for both inorganic and organic compounds. This is especially useful when detection of water is needed in GC x GC applications. When krypton is doped in the helium discharge gas (Mini Kr-PDD), it can suppress signals of compounds having higher ionization potentials and enhance relative signal intensities of aromatic compounds. The determination of aliphatic to aromatic hydrocarbon ratios is essential to the operation of petroleum crackers. Comparison of the signal from two modes of the Mini-PDD is a simple and fast way to verify the location of aromatics in comprehensive 2-D gas chromatograms.     

Determination of short-chain branching content in polyethylene by pyrolysis comprehensive multidimensional gas chromatography using low thermal mass column technology

A research effort was undertaken to utilize the pyrolysis process to create fragments of polyethylene that could be indicative of branching, and allow quantitiation of said short-chain branches by pyrolysis comprehensive 2-D GC (Py-GC x GC). Several strategies for sample introduction and pyrolysis such as the in-column pyrolysis device and the programmed temperature vaporizer (PTV) were studied. The chromatographic separations were executed using low-thermal mass (LTM) comprehensive 2-D GC (GC x GC). A series of polyethylene-co-hexene samples were analyzed and a linear correlation of 1-hexene content with branching peak ratio was found. Correlation coefficients were determined as 0.97 for the measurements performed.     

The potential of composite pyrolysis gas chromatographic mass spectra in the study of lignocellulosics

The objective of this work was to evaluate the use of composite mass spectral (CMS) data from pyrolysis gas chromatography/mass spectrometry (PY–GC/MS) for lignocellulosic materials. Various forages, by-products and fiber fractions derived from them were examined as CMS by PY–GC/MS. The PY–GC/MS system consisted of a heated platinum filament, a capillary gas chromatograph and an ion trap detector (ITD) mass spectrometer operated under electron impact conditions. Mass spectra were then composited in several ways by summing all the mass spectra acquired within retention times corresponding to major product classes. CMS data were entered in a dedicated library and compared using the ITD library editor software. The usefulness of such a simple procedure for studies related to lignocellulose analysis, such as forage recognition, development of analytical methods and digestibility/maturity correlation, is discussed.     

Application of off-line pyrolysis with dynamic solid-phase microextraction to the GC–MS analysis of biomass pyrolysis products

Pyrolysis coupled with dynamic solid-phase micro extraction (Py-SPME) followed by GC–MS analysis was applied to the determination of volatile compounds evolved by a micro-scale off-line pyrolysis apparatus, in order to extend the information affordable with this type of analytical equipment. The Py-SPME method with a carboxen/PDMS fiber working in the retracted mode was tested on four biomass samples (switchgrass, sweet sorghum, corn stalk and poplar) for qualitative analysis of semi-volatile pyrolysis products and quantitative determination of main volatiles (C₁–C₄) pyrolysis products. The developed procedure allowed capturing and analysis of all GC analyzable compounds, without memory effects and with good peak resolution also for early GC-eluting compounds. Twelve main volatile pyrolysis products, including hydroxyacetaldehyde and acetic acid, were successfully quantified; in spite of the intrinsic variability introduced by dynamic SPME sampling, results were relatively accurate and consistent with literature data on bench pyrolysis reactors.     

Highly selective and sensitive gas chromatography-electron-capture negative-ion mass spectrometry method for the indirect enantioselective identification of 2- and 3-hydroxy fatty acids in food and biological samples

A gas chromatographic (GC) method is described for the indirect enantioresolution of 2- and 3-hydroxy fatty acids (OH-FAs). It combines the derivatization of each alkylated enantiomer and the subsequent transfer with (R)-(-)-alpha-methoxy-alpha-trifluoromethylphenylacetyl chloride [(R)-(-)-MTPA-Cl, Mosher's reagent] into a diastereomeric (S)-MTPA derivative. The enantiomers of each derivatized OH-FA were well separated on three non-chiral GC-columns (CP-Sil 2, CP-Sil 8/20% C18 and VF-5ms). The derivatives were detected with high sensitivity by GC with electron-capture detection (GC/ECD) and electron-capture negative-ion mass spectrometry (GC/ECNI-MS) because of their enhanced electron-capturing properties. When applied to sunflower oil spiked with a small amount of a racemic 2-OH-FA, the present method allowed for a highly selective identification without influence from the sample matrix. For more complex samples such as wool wax, GC/ECNI-MS was superior to GC/ECD, since the high sensitivity of this method was linked with high selectivity. Using GC/ECNI-MS in the selected ion monitoring (SIM) mode, 16 enantiopure 2-OH-FAs were detected in a wool wax sample.     

A Review of Synthetic Polymer Characterization by Pyrolysis–GC–MS

Pyrolysis–GC with mass spectrometry detection (Py–GC–MSD) study of the thermal degradation products of synthetic polymers is reviewed. Due to the high heating speed, accurate temperature reproducibility and a wide temperature range, Py–GC–MSD has been applied successfully for polymer characterization. Introduction of samples using the pyrolysis carrier gas through the split injection port, followed by sub-ambient cryofocusing of the pyrolysis products, has shown to give reproducible chromatograms (pyrograms). One of the advantages of this method is that all compositions of the polymers and additives can be investigated without any pretreatment, providing important compositional and structural information in a simple way. The method is a convenient method for compositional analysis of complex polymer materials. The aim of this review is to describe the kinds of applications for which Py–GC–MSD has been found to be suitable; to present guidelines for method optimization; to survey innovations that have recently been developed or are currently being researched; to point to problems in our understanding of the pyrograms; and to suggest areas in which research efforts might be most effective in realizing the full potential of this technique.