气相色谱-质谱法研究敌百虫在气相色谱分析过程中产生的分解产物

利用气相色谱-质谱联用技术对敌百虫在气相色谱分析过程中产生的分解产物进行定性研究。通过质谱解析鉴定出敌百虫的分解产物有三氯乙醛、磷酸二甲酯和敌敌畏。研究了气相色谱条件如进样口温度、柱温升温速率、进样方式对敌百虫分解产物的影响。实验结果表明:这3种因素对敌百虫的稳定性均有不同程度的影响,其中进样口温度是导致敌百虫分解的主要因素,进样口温度越高,敌百虫的分解量就越大。     

气相色谱-质谱法分析辛硫磷过程中热分解产物的研究

对辛硫磷在气相色谱分析过程中因热分解产生的分解产物进行定性与定量研究.采用气相色谱-质谱联用技术,通过质谱解析鉴定出辛硫磷的分解产物有苯甲腈、苯甲酰腈、苯乙腈和氰基苄基叉胺.研究了进样口温度、离子源温度、连接线温度等色谱与质谱条件对辛硫磷分解产物的影响,并确定氰基苄基叉胺为辛硫磷热分解的指示成分及定量分析的代表成分,从而为快速检测痕量辛硫磷提供了一种新的途径.     

二叔丁基过氧化物分解产物的气相色谱法测定

采用气相色谱法考察了二叔丁基过氧化物分解温度与分解量之间的关系,研究了二叔丁基过氧化物分解产物的组成。实验发现：作为主要热分解产物的峰面积与二叔丁基过氧化物的量之间在２２．９１～１１４．９３μｇ范围内呈线性关系。测定未知浓度的过氧化物试样,有较好的精密度。     

八配位β－二酮锆的质谱研究

八配位β－二酮锆的质谱研究梁泽斌柴璋，李碧钦（北方工业大学化学系，北京，１０００４１）（中国科学技术大学研究生院化学部）关键词β－二酮锆，质谱，分子离子八配位β－二酮锆是制做氧化锆膜的气相淀积源材料。了解这些化合物的气相分解历程以及分解产物对控制气相...     

神府烟煤快速热解特性研究

利用高频电炉对神府煤进行快速热解,研究了不同热解温度和停留时间下,固相和气相产物的性质。结果表明,煤焦的失重率及真密度随温度升高和时间的延长而增长。红外光谱结果表明,热解过程中,煤中含氢/含氧官能团分解,生成H₂、CO、CO₂、CH₄等气体,并且其分解程度随温度的升高和时间的延长而加深。气相产物中H₂和CO的释放量随温度的升高和时间的延长而增加,而CO₂和CH₄存在释放量的峰值。气相产物随温度的升高和时间的延长而增多,导致高温煤焦出现大量的孔隙和裂缝。     

二苯羟乙酸-3-喹咛环酯的气相色谱行为研究

气相色谱进样口的瞬时高温会使二苯羟乙酸-3-喹咛环酯(BZ,C21H23NO3)发生分解,经实验确定分解产物为二苯酮.温度越高,分解程度越严重.为解决此问题,采用冷柱头进样口取代传统的分流/不分流进样口,建立了新的BZ气相色谱测定方法.方法的线性范围为0.098～140.0 mg/L;相对标准偏差2.0%;检出限0.098 ng.     

气相色谱法测定草酸铁的热稳定性——一个高等无机化学实验

目前,高等学校的无机化学实验中,气相色谱用得很少。在无机化合物的热分析方面,常采用热失重和差热分析法,但从这两种方法不能直接了解热分解的产物是什么,各产物的比例是多少。     

一定条件下硝酸酯炸药与聚氨酯胶的相互作用研究

用气相质谱(GC-MS)、FTIR对在100℃下处理数十小时后的硝酸酯炸药、聚氨酯胶及二者隔离体系和接触体系的气相组分、凝聚相进行了表征。结果表明:两者直接接触后,彼此之间发生的变化主要由硝酸酯炸药发生分解产生的NO2促使聚氨酯胶的降解并加速自身的分解,聚氨酯胶的降解产物又进一步催化硝酸酯炸药的分解;两者间接接触后,各自释出的气氛对彼此的结构没有影响。     

一定条件下硝酸酯炸药与聚氨酯胶的相互作甩研究

用气相质谱（GC—MS）、FTIR对在100℃下处理数十小时后的硝酸酯炸药、聚氨酯胶及二者隔离体系和接触体系的气相组分、凝聚相进行了表征。结果表明：两者直接接触后,彼此之间发生的变化主要由硝酸酯炸药发生分解产生的NO2促使聚氨酯胶的降解并加速自身的分解,聚氨酯胶的降解产物又进一步催化硝酸酯炸药的分解;两者间接接触后,各自释出的气氛对彼此的结构没有影响。     

二氧化钛薄膜上三氯乙烯光催化氧化反应机理

 研究了二氧化钛薄膜上三氯乙烯(TCE)气相光催化氧化的反应机理. 结果表明,TCE气相光催化氧化反应生成的氯气可引发TCE的连锁反应. 当添加氯气的浓度相同时TCE表面光催化反应的初速率约为光化学反应初速率的2倍,说明连锁反应主要发生在催化剂表面. 氯可吸附在催化剂表面,作为电子的接受体抑制空穴与电子复合,提高TiO2光催化剂的活性. 除了TCE与吸附在催化剂表面的·OH的相互作用及反应产物/中间产物二氯乙酰氯的光催化分解可生成氯气以外,光气在与氯气共存时的光分解也有利于氯的生成.     

Synthesis and characterization of bis(organothiolato)mercury(ii) complexes by disproportionation of Hg2Cl2 in the presence of thiols

Mercury(I) chloride disproportionates to mercury metal and bis(organothiolato)mercury(II) in the presence of some thiols in good yields. The products were analyzed by means of ¹H?NMR and gas chromatographic–mass spectrometry (GC/MS), which indicated that the complexes are monomers in the gas phase and decomposed at elevated temperature to mercury(0) and corresponding disulfides.     

Gas-chromatographische Bestimmung von Trichlorfon in biologischen Medien und technischen Produkten durch Derivatisierung mit Acetanhydrid

Zusammenfassung Eine gas-chromatographische Methode zur Bestimmung von Trichlorfon wird beschrieben, die auf der Acetylierung in der Säule mit Acetanhydrid beruht. Das gebildete Derivat O,O-Dimethyl-1-acetoxy-2,2,2-trichlorethylphosphonat wird mit dem Alkaliflammen-ionisationsdetektor (KCl) quantitativ bestimmt; der Linearitätsbereich liegt zwischen 0,1 und 2,0 ng. Zwei Standards von 0,45 und 1,65 ng Trichlorfon wurden elfmal mit einer relativen Standardabweichung der Peakhöhe von 8,4 und 5,4% injiziert. Beispiele zur Rückstandsbestimmung in Blut, Milch, Insekten und zur Analyse technischer Produkte werden gegeben. Trichlorfon kann neben Dichlorvos (DDVP) und Butonat sicher bestimmt werden.

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Determination of trichlorfon in biological media and technical products following derivatization with acetic anhydride by gas chromatography

Summary The method described is based on the on-column derivatization by acetic anhydride and determination of the derivative O,O-dimethyl-1-acetoxy-2,2,2-trichlorethylphosphonate by the alkali flame ionization detector (KCl). The response is linear over a range of 0.1–2.0 ng. Two standards of 0.45 and 1.65 ng of trichlorfon were injected eleven times with a relative standard deviation in peak height of 8.4 and 5.4%, respectively. Examples of residue determination in blood, milk, insects and of analyses of technical products are given. The determination of trichlorfon in the presence of dichlorvos and butonate is possible with certainty.

     

<Superscript>31</Superscript>P NMR and computer simulations of the structure of trichlorfon and its derivatives

Trichlorfon or O,O-dimethyl-(2,2,2-trichloro-1-hydroxyethyl) phosphonate is an organophosphorus insecticide with cholinesterase inhibitor activity that has been widely used in protection of field and fruit crops. Trichlorfon rearranges to other more toxic organophosphate insecticides (such as dichlorvos at pH 6–8) in aqueous media. Trichlorfon is a thermally labile compound that cannot be easily determined by gas chromatography coupled with mass spectrometry (GC-MS) and has no functional group for sensitive detection by high performance liquid chromatography (HPLC). In this study, ³¹P dynamic nuclear magnetic resonance is used to elucidate the stability of trichlorfon and derivatives. These spectrums are compared with the theoretical studies with the Gaussian software to determine the stability and identify the structure. Two derivatives are identified by this method.     

Autoxidation products of normal and genetically modified canola oil varieties determined using liquid chromatography with mass spectrometric detection

Normal, high stearic acid and high lauric acid canola oil varieties were heated in the presence of air to allow autoxidation to occur. After the reaction, the oils were analyzed using a non-aqueous reversed-phase high-performance liquid chromatographic separation followed by detection using atmospheric pressure chemical ionization mass spectrometry. Oxidized products were separated and identified. The major autoxidation products which remained intact were epoxides and hydroperoxides. Two classes of epoxy triacylglycerols (TAGs) were formed. One class with the epoxy group replacing a site of unsaturation and one class adjacent to a site of unsaturation, as was previously reported for model TAGs. Intact oxidation products resulted mostly from oxidation of oleic acid, while oxidation products of linoleic and linolenic acid chains decomposed to yield chain-shortened species. Both neutral and polar chain-shortened products were observed. Polar chain-shortened decomposition products eluted at very short retention times and required a different chromatographic gradient to separate the molecules. This class of molecules was tentatively identified as core aldehydes. The high stearic acid canola oil yielded more intact oxidation products containing stearic acid, as expected. The high lauric acid oil produced intact oxidation products which contained lauric acid.     

Trennung der Rückstoßprodukte von Ra-224- und Cf-252-Quellen durch Bildung von Alkylverbindungen

A new method for the separation of recoil atoms produced by the decay of Ra-224 was developed applying alkyl radicals. Argon was used as carrier gas and the transported alkyl compounds thermally decomposed in front of a GeLi-detector. Under the experimental conditions Pb-212 and Bi-212 could be transported with high yields whereas transport of Tl-208 could not be proved. Their was no interference of the measurements by Rn-220. Using Cf-252 as a source for fission products the recoil atoms were stopped in argon (about 4 atm). The thermalized recoil products were mixed with alkyl radicals and the possibly formed alkyl compounds thermally decomposed in front of a detector. In the experiments with pure argon as inert gas high yields of iodine were found.     

Methylation analysis in glycoprotein chemistry. General procedure for quantification of the products of solvolysis of permethylated glycopeptides and glycoproteins

A technique for the gas chromatographic analysis of the products of solvolysis of permethylated glycopeptides and glycoproteins has been developed. It involves methanolysis of a permethylated compound, quantitative transformation of methyl ethers of methyl glycosides into the corresponding O-trimethylsilyl(TMS)-O-methylalditols [2-deoxy-2-(N-methyl)acetamido-O-TMS-O-methylalditols in the case of hexosamine derivatives] and gas chromatographic quantification using a single column packed with 0.4% OV-225 on surface-modified Chromosorb.     

Heterogeneous Methane Conversion Processes Induced by a Pulse Microwave Discharge Near a Metal Surface

The degradation of methane in the batch mode by the action of a one-atmosphere pulse microwave discharge excited in a quartz reactor partially filled by a nickel gauze was studied. The fashion of gauze layout ensuring the sustainable excitation of discharge at an average power of 60–150 W and a pulse on/off ratio of 10 was described. Measurements of a pressure rise in the system simultaneously with the chromatographic analysis of the gas mixture sampled from the reactor showed that the product buildup kinetics were determined by the discharge character: when the discharge was maintained in the form of multiple sparks throughout the gauze-filled volume, the highest degradation rate was observed and all the products detected, including benzene, accumulated linearly with respect to the amount of methane decomposed. In the case of the formation of a local discharge zone in which the gauze was heated to a yellow heat, the benzene buildup followed a nonlinear law, its formation rate increased a few times with an increase in the degree of methane conversion. Although the total methane decomposition rate was lower in this case, conversion into benzene turned out to be a few times greater than in the previous experiment. For example, no more than 10–20% of methane decomposed within a discharge time of 10 min, whereas its conversion to benzene reached 10–15%.     

Rapid extraction and analysis of organic compounds from solid samples using coupled supercritical fluid extraction/gas chromatography

Summary Direct coupling of supercritical fluid extractions with gas chromatography (SFE-GC) allows the extraction, concentration, and gas chromatographic analysis of organic analytes from solid samples to be performed in less than 1 h. Coupling of the supercritical fluid extraction step with a capillary gas chromatographic column is achieved using a standard on-column injector and requires no modification of the gas chromatograph. Maximum sensitivity is achieved and analyte degradation or loss is minimized since the extracted species are quantitatively transferred into the fusedsilica capillary gas chromatographic column where they are cryogenically focused prior to normal gas chromatographic analysis using flame ionization (SFE-GC/FID) or mass spectral (SFE-GC/MS) detection. SFE-GC analysis yields good chromatographic peak shapes that compare favorably with those obtained using standard on-column injection techniques. Class-selective extractions can be achieved by performing multiple SFE-GC analyses with different extraction pressures. The ability of coupled SFE-GC to yield rapid extraction and analysis of organic analytes is demonstrated for a variety of samples including polycyclic aromatic hydrocarbons (PAHs) from treated wood, urban dust, and river sediment, phenolic species from wood smoke particulates, nicotine from tobacco, biological markers from coal, and flavor components from food products.

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Schnelle Extraktion und Analyse von organischen Verbindungen aus festen Proben durch Kopplung von Extraktion mit überkritischen fluiden Phasen und GC