同位素比值质谱与激光吸收光谱分析水中氢氧同位素方法的比较

氢氧稳定同位素在研究地球水循环过程中发挥着重要作用。本研究采用激光光谱法和高温热转换元素-同位素比值质谱法测定水样中氢同位素,采用激光光谱法和CO₂-H₂O平衡-同位素比值质谱法测定水样中氧同位素。结果表明：使用原理不同的两种方法测定地下水、海水和大气降水样品,测定的δ²H和δ¹⁸O值的精密度与准确度相当,激光光谱法以其快速高效、低成本、样品用量少占有优势;但使用这两种方法测定土壤抽提水样品时,激光光谱法测定δ¹⁸O值与真值的偏差为0.34‰,而质谱法测定的偏差小于0.10‰;激光光谱法测定δ2H值与真值的偏差为2.3‰,而质谱法测定的偏差小于0.6‰,说明质谱法的结果明显优于激光光谱法。     

Time of flight mass spectrometry applied to the liquid chromatographic analysis of pesticides in water and food

Liquid chromatography coupled to mass spectrometry (LC-MS) is an excellent technique to determine trace levels of polar and thermolabile pesticides and their degradation products in complex matrices. LC-MS can be equipped with several mass analyzers, each of which provides unique features capable to identify, quantify, and resolve ambiguities by selecting appropriate ionization and acquisition parameters. We discuss in this review the use of LC coupled to (quadrupole) time-of-flight mass spectrometry (LC-(Q)ToF-MS) to determine the presence of target and non-target pesticides in water and food. This technique is characterized by operating at a resolving power of 10,000 or more. Therefore, it gives accurate masses for both parent and fragment ions and enables the measurement of the elemental formula of a compound achieving compound identification. In addition, the combination of quadrupole-ToF permits tandem mass spectrometry, provides more structural information, and enhances selectivity. The purpose of this article is to provide an overview on the state of art and applicability of liquid chromatography time-of-flight mass spectrometry (LC-ToF-MS), and liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QToF-MS) for the analysis of pesticides in environmental matrices and food. The performance of such techniques is depicted in terms of accurate mass measurement, fragmentation, and selectivity. The final section is devoted to describing the applicability of LC-(Q)ToF-MS to routine analysis of pesticides in food matrices, indicating those operational conditions and criteria used to screen, quantify, and identify target and "suspected" pesticides and their degradation products in water, fruits, and vegetables. The potential and future trends as well as limitations of LC-(Q)ToF-MS for pesticide monitoring are highlighted.     

国产高分辨飞行时间质谱仪在药物分子结构鉴定中的应用

为了考察自主研发的API-TOF MS 10000电喷雾高分辨飞行时间质谱仪（ESI-TOF MS）对离子准确质量数测定的准确性及其在新药研发中的应用前景,采用该仪器对新药研发中涉及的291个天然产物及合成物进行质谱分析。以三氟乙酸钠为内标物进行仪器质量轴校准,将测试得到的目标离子准确质量数与理论准确质量数对比,计算两者的相对误差。结果表明：248个样品的分子质量测试结果与预期一致;对其中202个样品进行高分辨质谱测试,所得实验值与理论准确质量数之间的相对误差均小于5×10^-6;与预期不一致的实验结果提示样品的结构解析有误,并得到了其他波谱数据的验证。采用API-TOF MS 10000和美国AB Sciex公司的QSIAR Elite型Q/TOF MS对抗癌药物马来酸阿法替尼和降糖药利格列汀杂质进行质谱分析。结果表明,自主研发的API-TOF MS 10000与国际同类仪器对药物分子准确质量数的测试结果无明显差异,可以提供化合物准确的分子质量和分子式信息,是新药研发中药物分子结构解析的有力工具。     

谱图准确度在高分辨飞行时间质谱分析有机炸药中的应用

应用实时直接分析-高分辨飞行时间质谱（DART-TOF MS）对2,4,6-三硝基甲苯（TNT）、环三亚甲基三硝铵（RDX）、环四亚甲基四硝铵（HMX）、季戊四醇四硝酸酯（PETN）四种常见的有机炸药进行精确质量质谱解析,结果表明,即使在高质量精度的质谱上也不能获得化合物唯一的分子式。借助MassWorks软件对飞行时间质谱数据进行噪音过滤及峰形校正处理,可大大改善高分辨飞行时间质谱对目标化合物分子式识别的准确度,提高定性的准确性,为高分辨质谱解析未知化合物提供参考     

Issues and opportunities in accelerator mass spectrometry for stable isotopes

Accelerator mass spectrometry (AMS) has developed in the last 30 years many notable applications to the spectrometry of radioisotopes, particularly in radiocarbon dating. The instrumentation science of trace element AMS (TEAMS) that analyzes stable isotopes, also called Accelerator SIMS or MegaSIMS, while unique in many features, has also shared in many of these significant advances and has pushed TEAMS sensitivity to concentration levels surpassing many competing mass spectroscopic technologies. This review examines recent instrumentation developments, the capabilities of the new instrumentation and discernable trends for future development.     

表面热电离同位素稀释质谱法的计算及质量分馏效应校正

表面热电离同位素稀释质谱法(ID-TIMS)是国际公认的基准方法之一。本文以稀释分析锶同位素为例,详细介绍了其计算和推导过程,提出基于指数近似模式的稀释分析同位素分馏校正的方法。该方法适用于校正含有两对参考比值的元素静态多接收稀释分析同位素比值的质量分馏,与指数校正方法和对数校正方法相比,计算过程更简单。还讨论了稀释剂同位素比值准确度对稀释分析同位素比值的影响及其质量分馏的校正方法,通过数学迭代计算质量分馏系数,得到稀释剂测量的质量分馏系数和准确的同位素比值。采用建立的质量分馏校正方法稀释分析NBS987,结果表明,在误差范围内与其参考值（⁸⁷Sr/⁸⁶Sr=0.710237±8（1σ））一致。     

铀材料分析中的无机与同位素质谱法研究进展

综述了近年来中国工程物理研究院材料研究所应用无机与同位素质谱法进行铀材料分析的相关研究工作。在痕量铀同位素测量方面,发展了一种以氧化石墨烯作为电离增强剂的热电离质谱制样技术,显著增强了电离效率。在铀材料中杂质元素分析方面,开发了基于微流控芯片与电感耦合等离子体质谱联用的在线分离、分析方法,提高了分析的自动化程度。在金属铀中杂质元素的辉光放电质谱直接测定方面,基于相对灵敏度因子影响因素的研究基础,获得了一套普适性的相对灵敏度因子,实现了缺乏基体匹配标准物质时的准确测定。利用飞行时间-二次离子质谱法研究了铀及铀合金的偏析行为、夹杂物的表征、氢化/氧化腐蚀行为,为铀材料研究提供了表征手段。最后,对无机与同位素质谱法用于铀材料分析的发展前景进行了展望。     

Accurate and precise determination of isotopic ratios by MC‐ICP‐MS: A review

For many decades the accurate and precise determination of isotope ratios has remained a very strong interest to many researchers due to its important applications in earth, environmental, biological, archeological, and medical sciences. Traditionally, thermal ionization mass spectrometry (TIMS) has been the technique of choice for achieving the highest accuracy and precision. However, recent developments in multi‐collector inductively coupled plasma mass spectrometry (MC‐ICP‐MS) have brought a new dimension to this field. In addition to its simple and robust sample introduction, high sample throughput, and high mass resolution, the flat‐topped peaks generated by this technique provide for accurate and precise determination of isotope ratios with precision reaching 0.001%, comparable to that achieved with TIMS. These features, in combination with the ability of the ICP source to ionize nearly all elements in the periodic table, have resulted in an increased use of MC‐ICP‐MS for such measurements in various sample matrices. To determine accurate and precise isotope ratios with MC‐ICP‐MS, utmost care must be exercised during sample preparation, optimization of the instrument, and mass bias corrections. Unfortunately, there are inconsistencies and errors evident in many MC‐ICP‐MS publications, including errors in mass bias correction models. This review examines “state‐of‐the‐art” methodologies presented in the literature for achievement of precise and accurate determinations of isotope ratios by MC‐ICP‐MS. Some general rules for such accurate and precise measurements are suggested, and calculations of combined uncertainty of the data using a few common mass bias correction models are outlined. © 2009 Crown in the right of Canada. Published by Wiley Periodicals, Inc., Mass Spec Rev 28:990–1011, 2009     

Nuclear applications of inorganic mass spectrometry

There are several basic characteristics of mass spectrometry that are not always fully appreciated by the science community. These characteristics include the distinction between relative and absolute isotope abundances, and the influence of isotope fractionation on the accuracy of isotopic measurements. These characteristics can be illustrated in the field of nuclear physics with reference to the measurement of nuclear parameters, which involve the use of enriched isotopes, and to test models of s‐, r‐, and p‐process nucleosynthesis. The power of isotope‐dilution mass spectrometry (IDMS) to measure trace elements in primitive meteorites to produce accurate Solar System abundances has been essential to the development of nuclear astrophysics. The variety of mass spectrometric instrumentation used to measure the isotopic composition of elements has sometimes been accompanied by a lack of implementation of basic mass spectrometric protocols which are applicable to all instruments. These metrological protocols are especially important in atomic weight determinations, but must also be carefully observed in cases where the anomalies might be very small, such as in studies of the daughter products of extinct radionuclides to decipher events in the early history of the Solar System. There are occasions in which misleading conclusions have been drawn from isotopic data derived from mass spectrometers where such protocols have been ignored. It is important to choose the mass spectrometer instrument most appropriate to the proposed experiment. The importance of the integrative nature of mass spectrometric measurements has been demonstrated by experiments in which long, double beta decay and geochronological decay half‐lives have been measured as an alternative to costly radioactive‐counting experiments. This characteristic is also illustrated in the measurement of spontaneous fission yields, which have accumulated over long periods of time. Mass spectrometry is also a valuable tool in the determination of neutron capture cross‐section measurements and the application of such determinations in Planetary Science. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 29:845–859, 2010     

液相色谱-同位素稀释质谱法测定血清生长激素

复杂基质中低丰度蛋白质的准确定量分析一直是蛋白质研究的重点和难点。随着质谱技术的飞速发展,同位素稀释质谱法成为血清中低丰度蛋白质准确定量分析的重要方法。本研究以同位素标记的人生长激素为内标,通过C12和C4色谱柱两次分离收集目标馏分,建立了基于离线二维高效液相色谱分离血清样本的新方法。然后,结合高效液相色谱 同位素稀释质谱法,准确定量了人血清低丰度蛋白质生长激素的含量。通过对模拟样品（空白血清添加已知质量生长激素标准物质,理论含量为12.00 ng/g）和国际比对样品中生长激素（浓度未知）的测量及不确定度计算,定量结果分别为（11.45±2.33） ng/g和（12.84±1.46） ng/g。该方法准确性高、重复性好,为复杂基质低丰度蛋白质的准确定量分析提供了一种有效的测量方法和可溯源的分析结果。     

Chemical ionization tandem mass spectrometer for the in situ measurement of methyl hydrogen peroxide

A new approach for measuring gas-phase methyl hydrogen peroxide [(MHP) CH(3)OOH] utilizing chemical ionization mass spectrometry is presented. Tandem mass spectrometry is used to avoid mass interferences that hindered previous attempts to measure atmospheric CH(3)OOH with CF(3)O(-) clustering chemistry. CH(3)OOH has been successfully measured in situ using this technique during both airborne and ground-based campaigns. The accuracy and precision for the MHP measurement are a function of water vapor mixing ratio. Typical precision at 500 pptv MHP and 100 ppmv H(2)O is ±80 pptv (2 sigma) for a 1 s integration period. The accuracy at 100 ppmv H(2)O is estimated to be better than ±40%. Chemical ionization tandem mass spectrometry shows considerable promise for the determination of in situ atmospheric trace gas mixing ratios where isobaric compounds or mass interferences impede accurate measurements.     

Mass spectrometry and isotopes: a century of research and discussion

In 1815, the British physician William Prout had advanced the theory that the molecular masses of elements were multiples of the mass of hydrogen. This "whole number rule" (and especially deviations from it) played an important role in the discussion whether elements could be mixtures of isotopes. F. Soddy's discovery (1910) that lead obtained by decay of uranium and of thorium differed in mass was considered a peculiarity of radioactive materials. The question of the existence of isotopes came up when the instruments developed by J.J. Thomson and by W. Wien to study cathode and canal rays by deflection in electric and magnetic fields were steadily improved. In 1913, Thomson mentioned a weak line at mass 22 accompanying the expected one at mass 20 when he analyzed the mass spectrum of neon. Subsequently Aston obtained the mass spectrum of chlorine with masses at 35 and 37. Still in 1921, Thomson objected heavily to the idea of isotopes. The isotope problem was finally settled, but more accurate mass measurements showed that even isotopic weights differed to some extent from the whole numbers. Based on earlier ideas of P. Langevin and J.-L. Costa, F.W. Aston and A.J. Dempster developed the idea of packing fractions and mass defects due to the transformation of a portion of the matter comprising the atomic nucleus into energy. While the determination of the exact isotopic masses had improved over the years, the accurate determination of isotopic abundances remained a problem as long as photographic recording was used. Here especially A.O. Nier pioneered using dual collectors and compensation measurements. This was the prerequisite for the discovery that isotopic ratios varied somewhat in nature. M. Dole discovered the fractionation of oxygen isotopes by photosynthesis and respiration. Today 13C/12C-ratios are employed to detect adulterations of food and in doping analysis, and 14C/13C-ratios obtained by accelerator mass spectrometry are used for dating historical objects, just to give some examples.     

蜜环菌己素（armillarigin）的结构测定

本文报告了蜜环菌己素(armillarigin,6)结构的质谱测定,证明其为倍半萜醇芳香酸酯类。     

电感耦合等离子体质谱测量硒的研究进展

近年来,准确测量生物、食品、环境、地质等样品中的硒元素含量、同位素组成及其各种形态受到越来越多的关注。随着质谱技术的发展,电感耦合等离子体质谱(ICP-MS)技术成为硒的各种特性量研究和测量的重要手段,使其在生命科学、环境地球化学、生物、营养等研究中有着广泛的应用前景。本文综述了ICP-MS法应用于硒同位素比值,元素总量以及多种形态测量技术方面的最新研究进展。     

高功率激光电离飞行时间质谱技术

对于传统的高功率激光质谱存在的关键问题,如离子动能分散、多价离子和多原子离子干扰、基体效应和分馏效应等,高功率激光电离飞行时间质谱(LI-TOF MS)通过仪器结构设计及实验条件的优化等可以很好地解决。目前,LI-TOF MS的应用包括地质和金属样品中元素的定性和无标样半定量分析、非金属元素的测定、元素表面成像分析和薄层的深度剖析、液体残渣分析、复杂生物材料中元素组成的确定,甚至对于有机金属化合物也可以同时获得分子、碎片和元素信息。本工作综述了LI-TOF MS技术的发展历程,分析了其在不同领域中的优势,并对其应用领域拓展的新方向和仪器的改进目标进行了展望。     

一种应用于煤化工行业过程监测的质谱定量分析方法

为了满足煤化工行业对生产工艺监测与过程控制的需要，建立了一种在线质谱定量分析方法。相比传统在线色谱在煤化工过程监测中的应用，在线质谱监测系统具有实时在线测量组分多、响应速度快、稳定性好、动态范围宽等优点。采用聚光科技Mars-550过程气体质谱分析仪，建立了一种应用于工业过程监控的质谱定量分析方法，包括分析原理、数据采集及处理方法。以合成氨工艺过程控制中气体组分浓度的监测为例，对定量离子的选取、数据处理和结果分析进行了详细的阐述，定量相对误差小于1%。该方法具有实时、快速、准确、多流路、多组分分析的特点。     

碘的质谱测量方法研究进展

近年来,电感耦合等离子体质谱（ICP-MS）技术的发展着力于应对基质更加复杂的样品和解决测量过程中的干扰问题,同时与进样、分离系统的联用技术也在快速发展,而加速器质谱（AMS）则朝着更加小型化和更高灵敏度的方向发展。ICP-MS测量前需要对样品进行前处理以消解和提取碘,而AMS测量前则还需对样品进一步分离富集和纯化。本文总结了ICP-MS和AMS的发展概况及其在碘测量方面的应用,归纳了ICP-MS和AMS测量含碘样品的前处理方法,综述了国内外总碘、碘同位素及碘形态的质谱测量方法新进展。     

进样量和信号强度对气相色谱-燃烧-同位素比值质谱测定δ13C和δ15N的影响

采用气相色谱-燃烧-同位素比值质谱（GC-C-IRMS）法对咖啡因化合物和混合体系中特定氨基酸的δ13C和δ15N进行测定,在保证高测定精度和准确度的前提下,探讨GC C IRMS对进样量和信号强度变化的响应特征。分析结果表明,当C质量≥ 1 ng或m/z 44信号≥ 100 mV时,以及N质量≥5 ng或m/z 28信号≥ 100 mV时,咖啡因δ13C和δ15N测定结果的精度（<03‰）和准确度（<02‰）均能够满足实验室测试要求。针对混合体系中氨基酸δ13C和δ15N的测定,GC C IRMS可以在极少的进样量下实现对特定氨基酸色谱峰的有效分离。12种氨基酸δ13C测定结果未表现出对m/z 44信号强度的依赖性（斜率接近0）,其δ13C平均测定精度为056‰;而δ15N测定结果表现出良好的时间稳定性（4天）,与元素分析 稳定同位素比值质谱（EA IRMS）单独测定结果的平均偏差为077‰。     

离子阱质谱计的研究现状及其进展

离子阱质量分析器中离子的运动在数学上可用二阶线性微分方程——Mathieu方程的解来描述，利用离子在Mathieu方程解的稳定性图中所具有的特性，可实现离子的质谱扫描。离子阱质谱计的小型化主要集中在对离子阱质谱计各组成部分（离子源、质量分析器、离子检测、真空系统）的小型化上。随着科技的不断发展，离子阱质谱计体积的小型化，分析对象的不断扩大，仪器性能上实现大质量范围、高分辨率和高灵敏度，以及成本的有效降低等，将是离子阱质谱计相关研究的主要趋势。     

元素分析-稳定同位素质谱技术在婴幼儿配方奶粉奶源地追溯中的应用

婴幼儿配方奶粉是婴幼儿的主要食品,为加强其品质监管,建立了元素分析-稳定同位素质谱（EA-IRMS）同时测定婴幼儿配方奶粉中酪蛋白δ¹⁵N和δ¹³C值的方法。通过优化的等电点沉淀法可以从婴幼儿配方奶粉中获得高纯度的蛋白（纯度大于96%）。利用纳升液相-四极杆飞行时间质谱对提取的蛋白进行定性分析,确认其为酪蛋白。利用EA IRMS测定分离得到的酪蛋白δ¹⁵N和δ¹³C值发现,δ¹⁵N 和δ¹³C与奶源产地有一定的相关性,同一产地的婴幼儿配方奶粉中酪蛋白的δ¹⁵N和δ¹³C值分布范围一致,而不同奶源产地的则存在差异。该方法前处理简单、重现性好、测试方便、准确度高,可以用来追溯国内市场上婴幼儿配方奶粉的奶源产地。