不确定度优于0.035%的绝对光谱响应率标准探测器

讨论了由无窗硅光电二极管构成的反射式陷阱探测器的设计方案和工作原理 ,通过实验测试证明它具有良好的线性、空间响应均匀性、偏振非敏感性和稳定性。在可见波段的7个激光波长上（488nm-786nm),通过低温辐射计标定了陷阱探测器的绝对光谱响应率,不确定度小于0.035%,比现有的标准辐射源的精度提高了约2个量级,证明其可以作为高精度的绝对光谱响应率标准探测器。     

BaFeO3和BaCeO3钙钛矿型氧化物的储氮性能

 采用改进的溶胶－凝胶法制备了Ba－Fe－O（Ba／Fe原子比为0．5），Ba－Ce－O（Ba／Ce原子比为1）和Ba－Sn－O（Ba／Sn原子比为1）氧化物，并考察了其储氮性能．结果表明，750℃焙烧的Ba－Fe－O样品，在400℃下的NOx储存容量（NSC）最大，其次为900℃焙烧的Ba－Ce－O样品；相同温度焙烧的样品，在400℃下的NSC均大于200℃下的NSC．XRD测试结果表明，750℃焙烧的Ba－Fe－O样品的缺陷钙钛矿BaFeO3－δ可能是储存NOx的主要活性相，而Ba－Ce－O和Ba－Sn－O样品储存NOx的活性相分别为钙钛矿型BaCeO3和BaSnO3．BET测定结果表明，样品的比表面积均较小．用FT－IR分析了Ba－Fe－O样品上储存的NOx物种．讨论了NSC大小与吸收温度、NOx吸收物种及样品物相之间的关系．     

Ion trap tandem mass spectrometric determination of F2-isoprostanes

A new tandem mass spectrometry (MS/MS) method based on the use of an ion trap mass spectrometer for the identification and quantitation of F(2)-isoprostanes has been developed. It consists of two solid-phase extractions and two derivation steps followed by gas chromatography/negative ion chemical ionization tandem mass spectrometry (GC/NICI-MS/MS) analysis. This method is highly selective and sensitive and it has been successfully applied to biological samples.     

Ultra‐rapid non‐equilibrium solid‐phase microextraction at elevated temperatures and direct coupling to mass spectrometry for the analysis of lidocaine in urine

Solid‐phase microextraction (SPME) has been directly coupled to an ion‐trap mass spectrometer (MS) for the determination of the model compound lidocaine in urine, hereby applying MS/MS [fragmentation of [M + H]⁺ (m/z 235) to a fragment with m/z 86]. The throughput of samples has been increased using non‐equilibrium SPME with polydimethylsiloxane (PDMS) fibers. The effect of temperature on the sorption and the desorption was studied. Elevated temperatures during sorption (65°C) and desorption (55°C) had a considerable influence on the speed of the extraction. The desorption was carried out with a home‐made desorption chamber allowing thermostating. Only 1 min sorption and 1 min desorption were performed, after which MS detection took place, resulting in a total analysis time of 3 min. Detection limits below 1 ng/mL could be obtained despite yields of only 2.1 and 1.5% for a 100‐ and a 30‐μm PDMS‐coated fiber, respectively. Furthermore, the determination of lidocaine in urine had acceptable reproducibilities, i.e., relative standard deviations (RSDs) below 10%. A limit of quantitation (RSD < 15%) of about 1 ng/mL was obtained. No extra wash step of the extraction fiber was required after desorption if a 30‐μm coating was used, whereas not all the analyte was desorbed from the 100‐μm coating in a single desorption. Therefore, the SPME‐MS/MS system with a 30‐μm PDMS‐coated fiber for rapid non‐equilibrium SPME at elevated temperatures has interesting potential for high‐throughput analysis of biological samples.     

离子阱串联质谱法检测鱼肉中指示性多氯联苯

建立了使用离子阱串联质谱技术和同位素稀释技术准确测定鱼肉中的7种指示性多氯联苯（PCB）单体的方法。方法的检出限为0．025—0．068ng／g,6个加标鱼样（添加水平1ng／g）中7个单体的回收率为87.2％～103.7％,RSD为3．2％-8．7％（n=6）。本方法定量准确可靠,可用于食品中指示性PCB的测定。     

Quantitative determination of carbon concentration profiles by GD‐OES for the study of decarburization in low‐carbon steels

In this study, the quantification of decarburization induced during the annealing process for the fabrication of electrical steels was carried out using glow discharge optical emission spectroscopy (GD‐OES). Different calibration methods, based on external and internal standard references, were examined to optimize the quantification of carbon concentration. Accurate calibration curves for carbon at low concentration ranges were achieved by the use of carbon intensity calibrated by the internal reference, i.e. iron intensity line. This methodology was found to be beneficial for long GD‐OES measurements, providing a better correction over changes in the overall emission intensity with the sputter time. The good depth resolution obtained by the GD‐OES technique enabled the identification of specific features in the steel microstructure related to carbide coarseness. Quantitative carbon concentration profiles were obtained by GD‐OES to evaluate the decarburization effect on the microstructure of low‐carbon steels considering different initial microstructures. The effect of the spatial distribution of carbides in these microstructures on the decarburization kinetics was also studied. Through quantitative determination of carbon elemental profiles by GD‐OES, information about the morphology of the cementite in the microstructure and its development in relation to decarburization was acquired. The depth of decarburization can accurately be determined. On the basis of the global results, GD‐OES thus emerged as being a fast and reliable technique for a better understanding of decarburization kinetics. Copyright © 2015 John Wiley & Sons, Ltd.     

Ultra‐high performance liquid chromatography with linear ion trap‐Orbitrap hybrid mass spectrometry combined with a systematic strategy based on fragment ions for the rapid separation and characterization of components in Stellera chamaejasme extracts

Stellera chamaejasme, a famous toxic herb, has been used in traditional Chinese medicine to treat various diseases. For decades, increasing attention in modern pharmacological studies has been drawn to S. chamaejasme because of its potential anti‐tumor, anti‐virus, and anti‐fungus activities. However, due to the intrinsic complexity of chemical constitutes, hardly any investigations formed an overall recognition for the chemical profiles of this herb. In this study, a rapid and sensitive ultra‐high performance liquid chromatography coupled with linear ion trap‐Orbitrap mass spectrometry method was developed to characterize the chemical components of S. chamaejasme extracts. Based on optimized ultra‐high performance liquid chromatography and mass spectrometry conditions and systematic fragment ions‐based strategy, a total of 47 components including flavones, diterpenes, coumarins, and lignans were simultaneously detected and identified or tentatively identified for the first time. The MSⁿ fragmentation patterns of all the characterized compounds in positive or negative electrospray ionization modes were also explored and summarized. These results provided essential data for further pharmacological research on S. chamaejasme. Moreover, the method was demonstrated to be an efficient tool for rapid qualitative analysis of secondary metabolites from natural resources.     

捕集阱顶空气相色谱/质谱法测定水中的二氯一溴甲烷

建立了捕集阱顶空气相色谱/质谱测定水中二氯一溴甲烷的方法。采用正交实验设计对平衡温度、平衡时间、循环次数3个参数进行了优化,在平衡温度70 ℃、平衡时间20 min、循环次数2次的优化条件下,对水中的二氯一溴甲烷进行测定。结果显示,在0.1～10.0 μg/L范围内,二氯一溴甲烷的质量浓度和峰面积呈良好的线性关系,相关系数为0.9991。方法的检出限(S/N=3)为0.03 μg/L,定量限(S/N=10)为0.1 μg/L,回收率为83.1%～111.3%,相对标准偏差为1.7%～5.2%(n=6)。将该方法应用于水中二氯一溴甲烷的定性定量分析,效果良好。     

Degradation of poly(acrylates) under SF5+ primary ion bombardment studied using time‐of‐flight secondary ion mass spectrometry. 2. Poly(n‐alkyl methacrylates)

Polyatomic primary ions offer low penetration depth and high damage removal rates in some polymers, facilitating their use in the molecular depth profiling of these polymers by secondary ion mass spectrometry (SIMS). This study is the second in a series of systematic characterizations of the effect of polymer chemistry on degradation under polyatomic primary ion bombardment. In this study, time‐of‐flight SIMS (ToF‐SIMS) was used to measure the damage of ～90 nm thick spin‐cast poly(methyl methacrylate), poly(n‐butyl methacrylate), poly(n‐octyl methacrylate) and poly(n‐dodecyl methacrylate) films under extended (～2 × 10¹⁴ ions cm^?2) 5 keV SF₅⁺ bombardment. The degradation of the poly(n‐alkyl methacrylates) were compared to determine the effect of the length of the alkyl pendant group on their degradation under SF₅⁺ bombardment. The sputter rate and stability of the characteristic secondary ion intensities of these polymers decreased linearly with alkyl pendant group length, suggesting that lengthening the n‐alkyl pendant group resulted in increased loss of the alkyl pendant groups and intra‐ or intermolecular cross‐linking under SF₅⁺ bombardment. These results are partially at variance with the literature on the thermal degradation of these polymers, which suggested that these polymers degrade primarily via depolymerization with minimal intra‐ or intermolecular cross‐linking. Copyright © 2004 John Wiley & Sons, Ltd.     

Analysis of neutral oligosaccharides for structural characterization by matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry

We have acquired multi-stage mass spectra (MSn) of four branched N-glycans derived from human serum IgG by matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry (MALDI-QIT-TOF-MS) in order to demonstrate high sensitivity structural analysis. [M+H]+ and [M+Na]+ ions were detected in the positive mode. The detection limit of [M+Na]+ in MS/MS and MS3 measurements for structural analysis was found to be 100 fmol, better than that for [M+H]+. The [M+H]+ ions subsequently fragmented to produce predominantly a Y series of fragments, whereas [M+Na]+ ions fragmented to give a complex mixture of B and Y ions together with some cross-ring fragments. Three features of MALDI-QIT-CID fragmentation of [M+Na]+ were cleared by the analysis of MS/MS, MS3 and MS4 spectra: (1) the fragment ions resulting from the breaking of a bond are more easily generated than that from multi-bond dissociation; (2) the trimannosyl-chitobiose core is either hardly dissociated, easily ionized or it is easy to break a bond between N-acetylglucosamine and mannose; (3) the fragmentation by loss of only galactose from the non-reducing terminus is not observed. We could determine the existence ratios of candidates for each fragment ion in the MS/MS spectrum of [M+Na]+ by considering these features. These results indicate that MSn analysis of [M+Na]+ ions is more useful for the analysis of complicated oligosaccharide structures than MS/MS analysis of [M+H]+, owing to the higher sensitivity and enhanced structural information. Furthermore, two kinds of glycans, with differing branch structures, could be distinguished by comparing the relative fragment ion abundances in the MS3 spectrum of [M+Na]+. These analyses demonstrate that the MSn technology incorporated in MALDI-QIT-TOF-MS can facilitate the elucidation of structure of complex branched oligosaccharides.