顶空固相微萃取-全二维气相色谱/飞行时间质谱法分析闽南乌龙茶中的挥发性成分及其在分类中的应用

采用顶空固相微萃取(HS-SPME)结合全二维气相色谱/飞行时间质谱(GC×GC-TOF MS)分析了闽南乌龙茶中的挥发性成分。从48份不同等级和产季的乌龙茶(铁观音、黄金桂、本山、毛蟹和梅占)中获得了2000余种挥发性化合物,经筛选得到51种共有组分,并结合质谱数据库、保留指数与结构谱图等进行了初步鉴定。在此基础上采用主成分分析法(PCA)获得得分投影图,直观给出了不同样品的分类趋势。通过逐步判别获得9种对分类结果有显著影响的组分,并以此为变量通过Fisher判别法(FDA)建立了4个判别函数,对样品的分类准确率达到97.9%。本试验证实了以挥发性成分识别闽南乌龙茶的可行性。     

高效液相色谱-四极杆-飞行时间质谱快速筛查鉴别食品中非法添加的62种中药材北大核心CSCD

建立了高效液相色谱-四极杆-飞行时间质谱快速筛查鉴别食品中非法添加的62种中药材的方法。依据卫生部关于进一步规范保健食品原料管理的通知(卫法监发[2002]51号)中可用于保健食品的物品名单,确定食品中可能非法添加的62种中药材原料清单,再从62种中药材中筛选其特征组分,获得不同中药材对应的特征组分清单。62种对照药材经甲醇超声提取后,于Thermo Accucore aQ色谱柱(150 mm×2.1 mm,2.6μm)上分离,在电喷雾正负离子扫描模式下,分别以0.1%(v/v)甲酸水溶液-乙腈和水-乙腈为流动相梯度洗脱,进行一级质谱和二级质谱全扫描检测,采用Library View软件建立不同中药材对应的特征组分的一级精确质量数据库和二级碎片质谱库。样品同法处理后上样分析,采用Peak View软件将样品高分辨数据与自建数据库中的质谱图、精确分子离子质量数、碎片离子质量数、保留时间等相关参数进行快速筛查鉴别分析。该工作通过建立“中药材-特征组分”对应清单,构建了食品中易非法添加的62种中药材中共388种特征组分的高分辨质谱库,每种中药材包括5~10种特征组分,通过对实际食品样品配制酒、代用茶及饮料进行筛查分析,1批次配制酒样品与淫羊藿中药材的7种特征组分匹配一致,推断该配制酒样品中加入了淫羊藿中药材。该法可实现无标准品情况下中药材的定性筛查,具有高通量、准确、简便、快捷的特点,解决了食品中非法添加中药材难以识别和确证的难题,可以实现食品中非法添加中药材的快速筛查鉴别分析。     

Fisher判别在气相色谱-质谱分析助燃剂燃烧残留物中的应用

为寻找一种用于火场助燃剂燃烧残留物鉴定的更为准确、有效的模式识别方法,对7种常见助燃剂在不同载体上的燃烧残留物样品及未知送检样品进行气相色谱-质谱（GC-MS）分析测试,通过特征组分分析鉴定出未知样品中含有汽油成分。同时运用Fisher判别及PCA（主成分分析）/Fisher判别联用两种判别方法对样本数据进行了分析处理,PCA/Fisher判别联用的结果表明送检样本中含有硝基油漆稀料成分,而仅使用Fisher判别的结果表明送检样本中含有93^#汽油。通过将两种分析方法所得结果与GC-MS特征组分分析的结果进行比对发现,Fisher判别能够对7种助燃剂燃烧残留物的样本实现更有效的分类,对未知样本的判别更为有效。该研究结果为火场助燃剂鉴定提供了新的数据分析手段。     

蔗汁与朗姆酒香气成分相似性分析

运用气相色谱-质谱联用技术,通过HP-5MS弱极性柱以及HP-FFAP极性键合交联柱对朗姆酒及其原料蔗汁的挥发性组分进行分离鉴定,发现两者所含共同挥发性成分共13种,并根据每种化合物的感官特性推测其中甲酸、乙酸、丙酮(特殊辛辣气味)、糠醛(谷物香气)、5-羟甲基糠醛(甘菊花甜香气味)、双丙酮醇(有愉快香气)、二羟基丙酮(甜味、特殊香气)对蔗汁与朗姆酒香气相似性影响较大。     

有机硅烷KH—550的气相色谱／质谱分析

对硅-550交联剂的组分进行了研究报道。通过GC对样品进行了研究分析,得到了七个分离很好的色谱峰以及样品中各组分的含量,再利用GC/MS联用技术和质谱裂解规律鉴定出样品各组分的分子结构。     

甲苯二异氰酸酯的气相色谱-质谱分析

采用气相色谱－质谱分析甲苯二异氰酸酯（TDI）,以TDI80为例,对测试过程中样品的存放、溶剂及色谱条件的选择、组分定量作了探讨,获得满意的结果。该法无需标样,具有定性定量准确、简便的特点。     

人工神经网络用于直接化学电离质谱分析食用油品质的研究

无需任何样品预处理,采用表面解吸常压化学电离质谱(DAPCI-MS)技术直接对涂覆在载玻片表面的食用油样品和地沟油样品进行检测,快速获得了不同油类样品的质谱信号;并运用改进的反向传输(BP)人工神经网络对DAPCI-MS所得到的油类样品质谱数据进行有监督的分类识别,建立多分组预测模型。结果表明:DAPCI-MS能够承受食用油中复杂基体的影响,可对油类样品进行直接快速质谱分析;误差反转(BP)神经网络具有良好的分类判别能力,对食用油样品质谱数据识别效果比较理想,能够在对地沟油和非地沟油样品进行有效区分的同时,实现对不同品种的食用油的分离及分类判别。本方法分析速度快,信息提取准确,识别精度高,对快速质谱技术结合神经网络在该领域的应用以及食用油品质的快速鉴定具有重要的借鉴意义。     

基于高光谱成像技术的配方烟丝组分判别

应用近红外（1 000～2 200 nm）高光谱成像技术开展了面对像素、面对样本的配方烟丝 4种组分（叶 丝、梗丝、薄片丝、膨胀丝） 的判别研究。以样本高光谱图像的所有像素点光谱数据进行面对像素的组分判 别;以样本所有像素点的平均光谱数据进行面对样本的组分判别。采用二阶导数法结合萨维茨基－戈莱平滑 （SG）滤波对光谱数据进行预处理。通过面对像素数据的主成分分析,证实了基于面对像素的高光谱数据进行 组分判别的可行性,以前5主成分建立的支持向量机模型很好地实现了叶丝与梗丝、叶丝与薄片丝的判别任 务。建立了面对样本的4组分的K近邻和支持向量机判别模型,通过连续投影算法和二阶导数法进行特征波 长选择,筛选出具有高判别准确率的波段,组分判别率达86. 97%。     

基于液相色谱-四极杆/飞行时间质谱和化学计量学的婴幼儿配方乳粉化学指纹图研究

在反相色谱条件下,采用液相色谱-飞行时间串联质谱技术检测了18种婴幼儿配方乳粉,并应用主成分分析技术对大量的实验数据进行统计分析处理,研究了不同数据提取参数对分析结果的影响,通过T值检验筛选出3种罐标显示添加水解蛋白的婴幼儿配方乳粉的特征组分,提出了其中G号样品的16个特征组分的化学信息,并构建了相关的化学指纹图。     

免疫算法用于复杂样品的GC-MS快速分析

建立了一种基于免疫算法的复杂样品气相色谱-质谱联用(GC-MS)快速分析方法, 该方法采用快速温度程序测定复杂样品的GC-MS信号, 再通过快速解析得到各组分的信息. 计算过程中, 采用各种可能存在于混合物中的组分质谱作为算法的输入, 按照保留时间的顺序逐一对重叠的质谱信号进行解析, 得到各组分的色谱信息. 对于混合物中实际存在的组分可得到该组分的色谱流出曲线, 而对于混合物中不存在的组分所得色谱流出曲线几乎为零. 采用所建立的方法对含有16个组分的有机磷农药混合物进行了分析, 在保留时间10 min内得到了所有组分的色谱信息.     

纳米材料的结构分析

介绍宏观与微观的纳米粒子具有特殊的结构与性能,采用现代分析测试技术确定纳米材料的结构,并探索其原子或分子组成的规律是目前纳米科学的最微处理的研究内容之一。评述了纳米材料结构分析方法及理论研究的新成果。     

固相微萃取技术在形态分析中的应用进展

形态分析比传统的元素分析能提供更为丰富的信息，成为当今分析化学领域前沿课题之一，而固相微萃取（SPME)是近十年来发展起来的新型分离富集技术，简便快速、无污染、易于和其它技术联用．近几年来才开始将固相微萃取应用到形态分析，二者结合对形态分析的发展具有促进作用，本文就固相微萃取技术在元素有机化合物形态分析中的应用进行了评述．     

Assessment of Additives for Nitrogen, Carbon, Hydrogen and Sulfur Determination by Organic Elemental Analysis

 A survey is reported on the use of additives in organic elemental analysis of compounds containing functional groups that may compromise the combustion process. 28 substances containing the following functional groups were selected: organic fluorine, hexafluorophosphate, tetrafluoroborate, tetraphenylborate, sulfonate, phosphine, nitrile, carbide, organometallic. Six additives (powdered silver, silver tungstate with magnesium oxide, silica oxide, tungsten (VI) oxide with magnesium oxide, powdered tin, cerium (IV) oxide) in various sample:additive ratios were assayed. Silver tungstate with magnesium oxide (mixture 1:1, w/w) turned out to be most efficient for the analysis of nitrogen, carbon, hydrogen and sulfur for almost all the compounds assayed. Author for correspondence. Received August 2, 2002; accepted December 12, 2002 Published online May 19, 2003     

X射线荧光光谱分析

本文是“分析试验室”定期评述中“Ｘ射线荧光光谱分析”学科的第五篇评述。它收集了国内学者１９９２年７月到１９９４年６月期间发表在国内外刊物上的１７１篇文章，并对此期间我国Ｘ射线荧光光谱分析的概况和发展进行评述。内容包括ＸＲＦ仪器，同步辐射ＸＲＦ，全反射ＸＲＦ，粒子激发Ｘ线发射光谱，定量分析方法，制样技术，以及在各个科学烽戒严领域中的应用。     

Light Element Analysis of Individual Microparticles Using Thin-Window EPMA

 The determination of the concentration of light elements, such as carbon, nitrogen and oxygen, in e.g. atmospheric aerosol particles is important to study the chemical behaviour of atmospheric pollution. The knowledge of low-Z element concentrations gives us information on the speciation of nutrients (species having nutritional value for plants) and toxic heavy metals in the particles. The capability of the conventional energy-dispersive EPMA is strongly limited for the analysis of low-Z elements, mainly because the Be window in the EDX detector hinders the detection of characteristic X-rays of light elements such as C, N, O and Na. WDS is suitable for analysis of light elements, but the measurement of beam sensitive microparticles requires the minimisation of the beam current and the measurement time. A semi-quantitative analytical method based on EPMA using an ultra-thin window EDX detector was developed. It was found that the matrix and geometric effects that are important for low-energy X-rays can be reliably evaluated by Monte Carlo calculations. Therefore, the quantification part of the method contains reverse Monte Carlo calculation done by iterative simulations. The method was standardised and tested by measurements on single particles with known chemical compositions. Beam-sensitive particles such as ammonium-sulphate and ammonium-nitrate were analysed using a liquid nitrogen cooled sample stage. The shape and size of the particles, which are important for the simulations, were determined using a high-magnification secondary electron image. Individual marine aerosol particles collected over the North Sea by a nine-stage Berner cascade impactor were analysed using this new method. Preliminary results on five samples and 4500 particles show that the method can be used to study the modification of sea-salt particles in the troposphere.     

Coupling Cloud Point Extraction to Instrumental Detection Systems for Metal Analysis

The purpose of this article is to review and evaluate cloud point extraction of metals and its coupling to different contemporary instrumental methods of analysis. This review covers a selection of the literature published on this topic over the period mainly between 1997 and September 2005 (consisting of 50 publications). The current state of the art for CPE concerning metals and metal chelates is presented with special emphasis on the hyphenation of this interesting extraction/preconcentration approach mediated by surfactants to spectrophotometry, atomic spectroscopy and separation techniques. We present contemporary CPE developments concerning metal speciation and determination and their application to different environmental, clinical, geological and food samples. Strategies for method development as well as future perspectives are also covered.     

校准工作矩阵——目标因子分析光度法同时测定氨基酸混合体系

本提出一种应用传目标因子分析法的实用技术。通过确认一个相应的校准工作矩阵可对混合样品中的和组分进行同时直接定量。以二批六组分氨基酸混合样品（各组分浓度为２．０７２～”〕．１７０μｇ／ｍＬ０的分析表明，各组分绝大多数的回收率均在１００±１０％之内。该技术尤其适用于组成情况清楚的混合样品的例行分析。     

Applications of Electron Microbeam Analysis in the Earth Sciences

 Naturally formed geological materials are not constrained in the number of elements which may be present and a wide range of concentrations can be expected. Oxides are a frequent component and water may be present. The particular problems posed for quantitative analysis in some representative applications are described and solutions suggested. Critical testing of the results for consistency with mineral formulae and for repeatability provides confidence in those results. Examples of applications of quantitative analysis of minerals are used to show the variety of problems encountered in electron microbeam analysis and how the analytical results can be used to determine the conditions (time, pressure, temperature) of the minerals or the rocks in which they occur.     

Application of Continuous-Flow Liquid Phase Microextraction to the Analysis of Phenolic Compounds in Wastewater Samples

A novel method for the determination of phenolic compounds (phenol, o-cresol, m-cresol, 2,4-dimethylphenol, 2,3-dimethylphenol and 3,4-dimethylphenol) in water samples was developed by combined continuous-flow liquid-phase microextraction (CFME) with gas chromatography-flame ionization detection (GC-FID). The effects of extraction solvent type and volume, flow rate of sample solution, extraction time, salt concentration and pH on the extraction performance were investigated and optimized. The calibration curves and analyses of real samples were obtained under the following conditions: 3.0 μL n-Amyl acetate, 1.5 mL min⁻¹ flowing rate, 15 min extracting time and pH 1.5. The developed protocol was found to yield a linear calibration curve in the concentration ranged from 10 to 10000 μg L⁻¹ for the target analytes, and the limits of detection ranged from 2.32 to 2.95 μg L⁻¹. Good repeatabilities of extraction were obtained, with relative standard deviation (R.S.D.) values below 6.89%. The results demonstrated that the CFME followed with GC-FID is a simple and reliable technique for the determination of phenolic compounds in water samples.     

Arsenic Speciation Analysis in Solutions Treated with Zeolites

Experiments have been carried out to study the behaviour of organoarsenicals treated with zeolites by means of speciation analysis. IC-ICP-MS was applied to identify and quantify arsenite, arsenate and the following organoarsenicals: monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), trimethylarsine oxide (TMAO), tetramethylarsonium bromide (TMA⁺), arsenobetaine (AsB) and arsenocholine (AsC). Zeolites loaded with ferrous ions did not significantly increase the retention of inorganic arsenic species compared to the native zeolites, while there was a ten-fold removal of arsenate relating to arsenite. The formation of As(V) and DMA in the leachates containing clinoptilolites and mordenites was confirmed in the presence of natural and synthetic zeolites. Arsenobetaine and arsenocholine yielded higher levels of arsenate than the methylated species.