气相色谱法测定高纯三氯氢硅中的总碳含量

将高纯三氯氢硅中的含碳物质在氢气还原炉内转化成甲烷,利用配备氢火焰离子化检测器的气相色谱仪进行测定,最后换算成总碳的含量。结果发现,高纯三氯氢硅中的甲基二氯硅烷、甲基三氯硅烷、二甲基二氯硅烷等可能的含碳物质在转化炉内均具有良好的转化率,转化率大于85%。样品中含碳量的测定结果之间重复性好,精密度较高,相对标准偏差均小于10%。方法简单、快捷,准确度高,能很好地满足高纯三氯氢硅样品中对含碳物质的质量控制要求。     

合成三氯氢硅中聚氯硅烷与甲基氯硅烷形态分析

聚氯硅烷和甲基氯硅烷是合成三氯氢硅中的两类重要化合物。目前对这两类化合物的研究仅限于理论方面,通过实验数据进行的研究较少。采用气相色谱质谱联用技术对三氯氢硅合成中的聚氯硅烷形态进行了解析,确认六氯二硅烷是主要聚氯硅烷,其次是六氯二硅氧烷和五氯二硅烷;通过间接测试的方法实现了甲基氯硅烷与三氯氢硅、四氯化硅在HP-5ms色谱柱上的完全分离;并对合成氯硅烷中甲基氯硅烷的形态进行了分析和确认,其主要甲基氯硅烷有甲基二氯硅烷、二甲基氯硅烷、甲基三氯硅烷。     

分子直径法计算相对校正因子在气相色谱法测定三氯氢硅含量中的应用

在气相色谱法测定三氯氢硅含量中,采用分子直径法,以四氯化硅为标准物,计算氯化氢、二氯二氢硅、三氯氢硅在热导检测器上的相对校正因子,并以氦气为载气,测定三氯氢硅对四氯化硅的相对质量校正因子。未采用分子直径法得到的相对质量校正因子为0.891,采用分子直径法得到的相对质量校正因子为0.915,两者相对误差为1.13%。     

电感耦合等离子体质谱法测定三氯氢硅中12种杂质元素

<正>三氯氢硅(TCS)是改良西门子法生产多晶硅的中间产物,常态下为有刺激性恶臭、易流动、易挥发的无色透明液体,且极易在空气中燃烧[1]。在改良西门子法生产多晶硅的过程中,三氯氢硅的纯度对产品多晶硅的质量具有决定性作用,通过对TCS中杂质含量的检测,可以监控整个生产过程的洁净度,进而保证产品质量。太阳能级多晶硅制造业中,要求产品的纯度在99.99%~99.999 9%之间[2],杂质     

痕量硼的萃取比色法——用于三氯氢硅和四氯化硅中微量硼的测定

氟硼络阴离子BF_4~-与次甲基蓝阳离子形成蓝色络合物,微溶于水而易溶于有机溶剂如二氯乙烷。显色反应的灵敏度高,可用于微量硼的测定。显色条件和干扰离子的影响已见于文献。本工作采用微量萃取技术,使用自制聚乙烯萃取管和国产72型分光光度计,使硼的最低量可测定至1×10~(-8)克。当三氯氢硅和四氯化硅取样20毫升时,方法相对灵敏度为3或4×10~(-8)％。目前国内外多用化学光谱法测定三氯氢硅和四氯化硅中的硼,但有时,简便快速的比色法亦常应用于生     

流动体系高性能电流检测器的改进

采用在工作电极（ＷＥ）及辅助电极（ＣＥ）室衬垫尼龙网布的方法改进了本教研室提 出的 ＷＥ与ＣＥ正对面放置型的电流检测［１］。在进样 １００ μＬ样品（Ｂｒ－），流速２ ｍＬ／ｍｉｎ，检 测器电解效率达１８．９％，浓度电流线性范围为１０－２～１０－８ｍｏｌ／Ｌ，重复进样相对标准偏差小 于１％。     

钨（Ⅵ）与桑色素络合物的荧光胶束增敏作用

１引言Ｗ（Ⅵ）－桑色素（ｍｏｒｉｎ）－ＴｒｉｏｎＸ－１００体系测定Ｗ（Ⅵ）已见报道，但选择性不高。本文在高酸度条件下研究了多种类型表面活性剂对Ｗ－ｍｏｒｉｎ体系测定Ｗ（Ⅵ）的影响。建立了Ｗ－ｍｏｒｉｎ－ＣＴＭＡＢ体系测定Ｗ的方法。提高了方法的选择性。本方法用于福州温泉水中Ｗ（Ⅵ）的测定，获得满意的结果。２实验部分２．１仪器与试剂岛津ＲＦ－５４０，日立ＭＰＦ－４荧光分光光度计；Ｐ－Ｅ　λ－１７紫外可见分光光谱仪；本文中所用试剂均为分析纯或优级纯，所用水为石英亚沸蒸馏水。２．２实验方法于１０ｍＬ容量…     

电感耦合等离子体质谱法测定地质样品中铂、钯、钌、铑、铱和金

研究Ｔｅ共沉淀分离富集、ＩＣＰ－ＭＳ铂族元素和金测定方法。方法检出限 １～９ ｐｇ／ｇ;回收率≥９０％。国标ＧＢＷ０７２８８－ＧＢＷ０７２９４、加拿大ＷＧＢ１及南非铂矿ＳＡＲＭ７等标样分析表明：结果满意,方法可靠。     

不等活性缩聚反应动力学及其分子量分布Monte Carlo模拟

将缩聚产物分子量分布（ＭＷＤ）的ＭｏｎｔｅＣａｒｌｏ方法和聚合反应动力学的ＭｏｎｔｅＣａｒｌｏ方法结合起来，可在研究聚合反应动力学的同时获得ＭＷＤ随时间的变化．将该方法用于研究非等活性的ＡＢ—ＡＡ型缩聚反应的动力学与实验结果十分一致．通过考察高活性ＡＡ单体加入后对其动力学行为和相应的ＭＷＤ的影响，作者提出了对聚苯撑醚砜的ＡＢ型缩聚合成中加快其反应速度和改进ＭＷＤ的实用方法．     

二甲基甲酰胺催化的烯胺还原反应

用路易斯碱二甲基甲酰胺(DMF)催化三氯氢硅(HSiCl3)还原烯胺合成对应的胺,最佳反应条件为:烯胺0.1 mmol, DMF 0.5 eq., HSiCl3 4.0 eq., DCM 1 mL,于0 ℃反应12 h,胺的收率在93%以上.     

Impurity analysis of 1,4-dioxane in nonionic surfactants and cosmetics using headspace solid-phase microextraction coupled with gas chromatography and gas chromatography-mass spectrometry

1,4-Dioxane impurity in nonionic surfactants and cosmetics were analyzed using solid-phase microextraction (SPME) coupled with gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Experimental results show that there is no significant difference using SPME-GC and SPME-GC-MS for analysis of 1,4-dioxane in three types of nonionic surfactants at the 95% confidence level. The relative standard deviation (R.S.D.) values of each analytical method were smaller than 3%. The amount of 1,4-dioxane was found to vary from 11.6 +/- 0.3 ppm to 73.5 +/- 0.5 ppm in 30% of nonionic surfactants from manufacturers in Taiwan. These methods were linear over the studied range of 3-150 ppm with correlation coefficients higher than 0.995. The recoveries of 1,4-dioxane for these nonionic surfactants following SPME were all higher than 96 +/- 1% (n = 3). The detection limits of 1,4-dioxane for these nonionic surfactants following SPME were from 0.06 ppm to 0.51 ppm. The experimentally determined level of 1,4-dioxane in cosmetics from manufacturers in Taiwan varied from 4.2 +/- 0.1 ppm to 41.1 +/- 0.6 ppm in 22% of daily used cosmetics following SPME coupled with GC and GC-MS. Conventional solvent extraction takes around 1 h for extraction and reconcentration but SPME takes only around 10 min. SPME provides better analyses of 1,4-dioxane in nonionic surfactants and cosmetics than conventional solvent extraction and head space pretreatments in term of simplicity, speed, precision, detection limit, and solvent consumption.     

Determination of ethers and alcohols in reformulated gasolines by gas chromatography/atomic emission detection

A GC method for the determination of oxygenated additives in reformulated gasolines (RFG) is described. The method uses on-column injection and atomic emission selective detection of oxygenates using the 777 nm NIR emission line. Detection limits are approximately 10 ppm oxygen. Results compared well with other techniques, such as GC/FTIR.     

Determination of hydrazine in maleic hydrazide technical and pesticide formulations by gas chromatography: collaborative study

Twelve collaborating laboratories assayed hydrazine in technical maleic hydrazide (MH), 6-hydroxy-2H-pyridazin-3-one, and 2 formulated products, a liquid concentrate and a soluble granule, using gas chromatography (GC) with electron capture detection. The hydrazine content in the samples ranged from 0.03 ppm, in the liquid concentrate, to 0.26 ppm, in MH technical. Hydrazine and MH are dissolved in an aqueous solution. The MH is then precipitated out of solution by acidification. The solution containing hydrazine is treated with excess pentafluorobenzaldehyde (PFB) to form pentafluorobenzaldehyde azine (PFBA). The PFBA is extracted with hexane for analysis by GC using an electron capture detector. Peak area responses of PFBA are measured and quantified by external standardization. Hydrazine concentration is calculated from the PFBA determination. The laboratories weighed each test sample in duplicate with duplicate analysis for each weighing. Data from these laboratories were statistically analyzed. The average relative repeatability was determined to be 5.34% and the average relative reproducibility was 27.99%.     

Analytical determination of nicotine in tobacco leaves by gas chromatography–mass spectrometry

A preliminary investigation using gas chromatography–mass spectrometry (GC–MS) to analyze the nicotine contained in tobacco leaves was carried out. Nicotine is an alkaloid and tobacco leaves was extracted with methanol and determined by GC–MS. The detection limit for nicotine was at the ppm level for non selective monitoring and the nanogram level for selective detection. This is a simple chromatography–mass spectrometry method for the analysis of nicotine in tobacco leave. Compared to other currently utilized methods for the detection of nicotine in tobacco leaves, the GC–MS provided advantages of high sensitivity, nicotine specific detection and lower instrumentation cost.     

GC/FT-IR: A unique choice for solvent analysis

The analysis of solvents for both purity and component identifications is routinely performed by gas chromatography (GC). Coupling it with the latest FT-IR systems results in a technique which yields ppm sensitivity and excellent library search results.     

Nanocomposites of genipin-crosslinked chitosan/silver nanoparticles--structural reinforcement and antimicrobial properties

This study investigates the feasibility of a novel nanocomposite (GC/Ag) of a genipin-crosslinked chitosan (GC) film in which was embedded various amounts of Ag nanoparticles for wound-dressing applications. In situ UV-vis results revealed that adding chitosan solution did not affect the characteristics of Ag nanoparticles. The water uptake ratios and surface hydrophilicity of the GC/Ag nanocomposite were better and the degradation rates slightly lower than those of the pure GC film. The presence of Ag nanoparticles enhanced L929 cell attachment and growth. Its function as an anti-microbial agent in a GC/Ag nanocomposite was assessed for Ag contents of over 100 ppm. In conclusion, silver ions had dual functions--structural reinforcement and provision of antimicrobial properties to a biocompatible polymer.     

A very thick film open-tubular trap for headspace capillary gas chromatography

Summary An open-tubular trap with a very thick film was studied for “full on-line” headspace capillary gas chromatography, and was used as an enrichment trap for headspace sampling. The preparation of the open-tubular column with up to an 80 μm thick film, by combining both static and dynamic coating, is described in detail. The break-through volume for the open-tubular trap of different film thickness, as the loading capacity for HS sampling, does not increase linearly in proportion to the film thickness. A study of the difference between a packed adsorbent trap and an open-tubular trap shows that HS capillary GC with open-tubular trap loses less of the retention capacity, has better resolution ability and higher recovery. By independently and rapidly heating the open-tubular trap, the GC peaks may have higher resolution. Examples of successful analyses, by the opentubular trap with “full on-line” HS capillary GC, include trace aromatic hydrocarbon (1 ppm-100 ppm) in polybutadiene-styrene rubber and trace alcohol and acrylic esters (10 ppm–1000 ppm) in polyacrylate hydrous emulsion.     

Quantitation method of N,N ′‐disalicylidene‐1,2‐propanediamine by comprehensive two‐dimensional gas chromatography coupled to a nitrogen chemiluminescence detector

Metal deactivator additives (MDAs) have been used for over 60 years to prevent metal catalyzed reactions in petroleum products; a commonly used metal deactivator is N,N′‐disalicylidene‐1,2‐propanediamine. The quantitation of low MDA concentrations in fuels is challenging due to the complexity of the sample matrix. In this work, this difficulty was overcome using GC × GC hyphenated with a nitrogen chemiluminescence detector. The high resolution power of GC × GC avoided co‐elution between the MDA and other sample matrix compounds; while the enhanced sensitivity of GC × GC and the use of a nitrogen chemiluminescence detector supplied a high sensitivity and specificity for nitrogen compounds. For the analysis, the MDA additive was derivatized with the silylation agent N,O‐bis (trimethylsilyl)trifluoroacetamide at room temperature and its quantitation was based on an external calibration curve; good linear response was obtained in the 1.4–8.6 ppm range.     

Monitoring of trace levels of p-dioxan in high purity benzene feedstock by capillary gas chromatography

Summary A procedure has been standarized for the determination of p-dioxan (1,4-dioxan) in benzene feedstock in the range of 1 to 100 ppm by capillary GC. The GC conditions such as oven temperature, length of the column etc were optimized to achieve better resolution of p-dioxan from hydrocarbons. The standard addition method of quantitation, was used to determine the amount of p-dioxan and was found to give better results than those obtained by external standardization. Prior to analysis the identity of the p-dioxan peak was established by GC-MS. The proposed method has been applied for the monitoring of p-dioxan in high purity benzene feedstock produced by the Udex extraction process in the refinery. The data were used for optimization of plant conditions for the production of high purity benzene feedstock. By using this method, the p-dioxan content down to 0.5 ppm can be determined in the benzene feedstock.