Thermal Degradation Processes in Poly(xylylene sulfides) Investigated by Comparative Direct Pyrolysis MS and Flash Pyrolysis GC/MS Experiments

The thermal degradation processes of two sulfur polymers, poly(xylylene sulfide) (PXM) and poly(xylylene disulfide) (PXD), were investigated in parallel by direct pyrolysis mass spectrometry (DPMS) and flash pyrolysis GC/MS (Py-GC/MS). Thermogravimetric data showed that these polymers decompose with two separate steps in the temperature ranges of 250-280 and 600-650 degrees C, leaving a high amount of residue (about 50% at 800 degrees C). The pyrolysis products detected by DPMS in the first degradation step of PXM and PXD were terminated by three types of end groups, -CH3, -CH2SH, and -CH=S, originating from thermal cleavage reactions involving a series of homolytic chain scissions followed by hydrogen transfer reactions, generating several oligomers containing some intact xylylene sulfide repeating units. The presence of pyrolysis compounds containing some stilbene-like units in the first degradation step has also been observed. Their formation has been accounted for with a parallel cleavage involving the elimination of H2S from the PXM main chains. These unsaturated units can undergo cross-linking at higher temperatures, producing the high amount of char residue observed. The thermal degradation compounds detected by DPMS in the second decomposition step at about 600-650 degrees C were constituted of condensed aromatic molecules containing dihydrofenanthrene and fenanthrene units. These compounds might be generated from the polymer chains containing stilbene units, by isomerization and dehydrogenation reactions. The pyrolysis products obtained in the Py-GC/MS of PXM and PXD at 610 degrees C are almost identical. The relative abundance in the pyrolysate and the spectral properties of the main pyrolysis products were found to be in generally good agreement with those obtained by DPMS. Polycyclic aromatic hydrocarbons (PAHs) were also detected by Py-GC/MS but in minor amounts with respect to DPMS. This apparent discrepancy was due to the simultaneous detection of PAHs together with all pyrolysis products in the Py-GC/MS, whereas in DPMS they were detected in the second thermal degradation step without the greatest part of pyrolysis compounds generated in the first degradation step. The results obtained by DPMS and PSI-GC/MS experiments showed complementary data for the degradation of PXM and PXD and, therefore, allowed the unequivocal formulation of the thermal degradation mechanism for these sulfur-containing polymers.

GC-MS study of Artabotrys odoratissimus fatty oil (leaves)

GC-MS study of two fatty oil fractions from Artabotrys odoratissimus (leaves) indicated the presence of fifteen compounds namely, nonanoic acid; methyl phenyl propanoate; decanoic acid; diethyl phthalate; dibutyl phthalate; 2 - amino-3-ethyl biphenyl; 5-methyl-9-phenylnonan-3-ol; hexadeca-2,7,11-triene; 2,6-dimethyl-1-phenylhepta-1-one; 2,5-dimethyltetradecahydrophenenthrene; 1-phenylundecane; 1-isopropyl-4,6-dimethyl naphthalene; 5-(2-butyl phenyl)pent-3-en-2-ol; 1-phenyideca-1-one and 1-phenylundecan-1-one. Some of the compounds are rare occurring and biologically active.

Determinación de compuestos orgánicos potencialmente alérgenos en equipos textiles de protección individual (EPIs) mediante analisis directo por pirólisis acoplado a cromatografía de gases espectrometría de masas (Py-GC/MS).

Nota de aplicación instrumental desarrollada en el Servicio Central de Análisis de Bizkaia (SCAB)

Metodología analítica para el control de calidad en ambientadores higiénicos basados en la cuantificación de sus componentes mediante cromatografía de gases acoplada a espectrometría de masas (GC/MS).

Nota técnica para el análisis de compuestos volátiles en fórmulas higiénicas

湖北栀子花挥发油的GC/MS分析

利用水蒸气蒸馏法从湖北栀子花鲜花中提取栀子花挥发油。通过 DB 5弹性石英毛细管柱 GC MS分析所得栀子花挥发油 ,共鉴定了 4 0个化合物并测定了其相对含量。湖北栀子花挥发油的主要成分为芳樟醇 ( 1 7 92 %)、茉莉内酯 ( 9 1 1 %)和惕各酸顺 3 己烯酯( 6 5 4 %)

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应用GC/MS联用技术,对除臭大蒜口服液进行了检测,定性鉴定了25种含硫有机化合物。二烯丙基硫醚、甲基烯丙基三硫醚、3-乙烯基-1,2-二硫杂-5-环己烯、2-乙烯基-1,3-二硫杂-5-环己烯和二烯丙基三硫醚是主要组分;二烯丙基四硫醚、烯丙基四硫化氢、2-和3-(2’,3’-二硫杂-5’-己烯基)-3,4-二氢-2H-噻喃、2-(2’-[3’,4’-二氢-2H噻喃基])-1,3-二硫杂-5-环己烯和3-(2’-[3’,4’-二氢-2H-噻喃基])-1,2-二硫杂-5-环己烯是次要组分。最后4种次要组分在

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东湖沉积物阴干后用二氯甲烷溶剂萃取，用ＤＢ－５弹性石英毛细管柱ＧＣ／ＭＳ分离鉴定，并结合ｍ／ｚ１４９质量色谱图，确证东湖沉积物中含有９种邻苯二甲酸酯类化合物，它们是邻苯二甲酸二乙酯、二异丁酯、二正丁酯、二己酯、己基辛基酯、二－（２－乙基己基）酯、二辛酯、己基癸基酯和辛基癸基酯，其特征离子及峰度见表１。

自来水中非挥发性氯化产物的GC／MS分析

本文采用ＸＡＤ－２和ＸＡＤ－８（１：１）混合树脂现场富集采样，循环提取器提取，毛细管ＧＣ／ＭＳ定性的方法，通过对冬夏两季的采样分析，初步分析了某地自来（饮用）水中非挥发性有机氯化产物。从夏天自来水中检测出了２８种有机氯化合物。从冬天自来水中只检出了１种有机氯化合物。

湖北大蒜油的GC/MS研究

<正> 1 简介与实验大蒜(Allium sativun L.)系石蒜科葱属植物,世界各地均有栽培,大蒜作为民间药物广泛应用于世界各地。我国用大蒜作为药物有悠久的历史,大蒜在临床上的重要作用引起了广大化学家的重视,对大蒜的分析国内外均有报道。Stoll 等人认为大蒜的主要成分是大蒜辣素(Allicm),其结构式为 CH_2=

珍稀水生动物白暨豚油中脂肪酸的GC/MS分析

白暨豚是一种珍稀水生动物.本文报道了运用 Dexsil-300GC 毛细管柱色质联用仪,对白(?)豚油中脂肪酸进行了分析鉴定,并检测到了22种脂肪酸,其中主要脂肪酸是十四碳烯酸、十六碳烯酸和十八碳烯酸.