Determination of Chromium (VI) in Airborne Particulate Matter by Electrothermal Atomic Absorption Spectrometry

Hexavalent chromium Cr(VI) is a well-established carcinogen associated with lung, nasal, and sinus cancer. Cr(VI) threshold limit values in workroom air have been recently lowered. Consequently, the currently available analytical methods are insufficiently sensitive or high cost. In this paper, a simple, cost-effective, sensitive, and reproducible method using solid-phase extraction with electrothermal atomic absorption spectrometry for determination of hexavalent chromium in airborne samples is reported. The method validation included selectivity, linearity, accuracy, and precision. Interferences from other ions likely to be present in airborne samples, including trivalent chromium, were tested and selectivity was demonstrated. The detection and quantification limits were, respectively, as low as 0.1 and 0.4?µg?L^?1. The linearity ranged from 0.5 to 50.0?µg?L^?1, with a regression coefficients exceeding 0.998. The extraction recovery exceeded 98%. The developed method was successfully compared with a reference spectrophotometric method. The performances achieved were similar to ion chromatography and high-performance liquid chromatography approaches. The novel method was tested on airborne samples collected from the workplace. The method’s performance suggests that it may be an alternative to high-cost techniques for monitoring occupational exposure to hexavalent chromium.     

石墨微粒柱电化学预富集-火焰原子吸收联用测定镉

以石墨微粒柱电极为工作电极,对溶液中痕量镉进行电化学预富集、溶出,并用火焰原子吸收分光光度法在线测定。极大的提高了测试灵敏度,降低检出限达1—2个数量级,富集倍数可达754倍。并就支持电解质种类和浓度,富集流速、电压,溶出液流速、电压,pH值对测定的影响作了深入的研究。     

石墨探针采样／石墨炉原子吸收光谱测定大气微粒物质中的痕量铁

采用一定规格的石墨探针直接收集大气微粒物质，并采用原子吸收光谱法测定其中的痕量铁。     

阳离子交换树脂分离电感耦合等离子体质谱法测定空气颗粒物中铂族元素

用Dowex AG50W-X8阳离子交换树脂分离空气颗粒物中Pt、Pd、Rh测定的干扰元素Cu、Ga、Hf、Pb、Rb、Sr、Y.模拟标准液实验确定出Dowex AG50W-X8阳离子交换树脂分离流程的最佳条件:上柱HCl浓度为0.8 mol/L,树脂柱床高为4 cm,洗脱速率为1 mL/min.铂族元素分析的国际标准物质BCR-723对照分析表明,Pt、Pd、Rh的测定值与标准值吻合,干扰元素Cu、Ga、Pb、Rb、Sr、Y的分离效率均大于94%,这表明所建立的Dowex AG50W-X8阳离子交换树脂分离流程是可靠的.     

Phase Correction for Absorption Mode Two-Dimensional Mass Spectrometry

Two-dimensional mass spectrometry (2D MS) is a tandem mass spectrometry method that relies on manipulating ion motions to correlate precursor and fragment ion signals. 2D mass spectra are obtained by performing a Fourier transform in both the precursor ion mass-to-charge ratio (m/z) dimension and the fragment ion m/z dimension. The phase of the ion signals evolves linearly in the precursor m/z dimension and quadratically in the fragment m/z dimension. This study demonstrates that phase-corrected absorption mode 2D mass spectrometry improves signal-to-noise ratios by a factor of 2 and resolving power by a factor of 2 in each dimension compared to magnitude mode. Furthermore, phase correction leads to an easier differentiation between ion signals and artefacts, and therefore easier data interpretation.     

石墨探针采集／原子吸收法测定大气微粒物质中痕量锰

大气微粒物质（APM）中痕量有害元素的含量是世界各国大气污染监测的主要分析项目之一［‘j．人体长期吸入含锰的烟尘，可引起慢性锰中毒［‘j．多孔的电石墨对于APM是理想的过滤材料，它适于收集亚微米和lum以上的大气微粒物质，并有着很高的收集效率［’‘．本文采用一定规格的石墨探针直接过滤收集APM，然后立即用石墨探针炉原子吸收光谱法测定收集在探针上的APM中痕量锰，这种直接固体进样技术，省去了常规滤膜法收集后冗长的样品化学前处理过程，避免了样品的泊污及分析物的损失．此采集／分析系统准确、灵敏、快捷、简便，采用此…     

Determination of Polycyclic Aromatic Hydrocarbons in Airborne Particulate by High Performance Liquid Chromatography

This paper presents a trisolvent ultrasonic extraction and HPLC analysis method for the determination of 11 polycyclic aromatic hydrocarbons in air particulate collected on an air filter by a commercial high volume air sampler. A reverse phase column, Vydac 201 TP, and a gradient mobile phase, acetonitrile/water, were used. The 11 PAHs, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a, h]anthracene, benzo[ghi]perylene, indeno[1,2,3-cd]pyrene, and coronene were completely resolved under experimental conditions. All the PAHs except coronene were monitored by fluorescence with λ_ex=270 nm, λ_em>389 nm. Coronene was monitored by UV with λ=300 nm. The methodology was evaluated by spiking SRM 1649 with a PAH standard and then going through different extraction procedures and analyzing the PAH concentrations without clean-up. An external standard method was used for quantitation. The recovery yields for fluoranthene, benz[a]anthracene, benzo[a]pyrene, benzo[ghi]perylene and indeno[l,2,3-cd]pyrene were above 90%. The detection limits of PAH with fluorescence at λ_ex=270 nm, λ_em>389 nm ranged from 5.7 pg to 69.5 pg.     

单颗粒气溶胶飞行时间质谱仪在细颗粒物研究中的应用和进展

单颗粒气溶胶质谱技术起源于20世纪70年代,在近二十年得到了快速的发展.单颗粒气溶胶飞行时间质谱仪具有高时间分辨率,且同时测量大气中单个细颗粒物粒径、多种化学组分和混合状态的特点,在大气细颗粒物监测和科学研究中逐渐得到了广泛应用.本文对单颗粒气溶胶飞行时间质谱仪的发展历程进行了介绍,对目前已商品化的单颗粒气溶胶飞行时间质谱仪ATOFMS和SPAMS的原理、数据分析方法、结果输出方式以及在环境监测和研究中的主要应用进行了总结,并指出单颗粒气溶胶飞行时间质谱仪的发展方向.     

中空纤维致密膜基吸收CO2传质过程

研究了硅橡胶/聚砜中空纤维致密膜基吸收CO2的传质机理,考察了吸收剂种类(NaOH,MEA,DEA和TEA)、NaOH浓度、吸收剂流速、吸收剂压力和气相压力对CO2传质通量及传质速率的影响.其中,用2×103mol/m3NaOH作吸收剂时,聚合物膜传质为控制步骤,其传质效率与膜自然渗透相近.     

二元颗粒混合物按质量取样的误差研究

二元颗粒混合物的随机取样方式有两种：一是按颗粒数目取样,二是按质量取样本文对二元颗粒混合物按质量取样的误差进行了深入研究,详细分析了混合物的各种参对被测组分含量取样误差的影响,应用Ｍｏｎｔｅ Ｃａｒｌｏ技术对取样进行了模拟。以颗粒药品的二元混合物为例对按颗粒数目取样和按质量取样的误差进行了比较。此项研究对于分析取样理论和应用具有重要的价值。     

The Corrected Value of the Y La Mass Absorption Coefficient in Silicon

In earlier experiments some irregular effects were observed in the X-ray spectra of yttrium doped -sialon ceramics. Yttrium L was totally absorbed whereas yttrium K was present in the spectra. Since the only reasonable explanation for these observations seems to be the effect of the silicon K-absorption edge on the entire absorption of the Y L, the experimental determination of the Y L mass absorption coefficient (mac) in silicon was performed. The silicon layer has been deposited by thermal vacuum evaporation simultaneously on the surfaces of the silica glass plate, the nickel plate and on the polished surface of the yttrium oxide sample. The silicon-covered silica glass plate was used for the layer thickness measurements (interference microscope). The silicon layer on the nickel plate was employed in the measurements of the Ni L mac value in silicon in order to verify the correctness and accuracy of the methodology. The yttrium L intensities were then measured at the silicon covered and uncovered parts of the yttrium oxide sample surface. The measured intensities were corrected with respect to the primary electron backscattering in silicon and their energy reduction in the layer. Typical EPMA instrumentation was used in all measurements. The value of the yttrium L mass absorption coefficient in silicon computed on the basis of the Lambert-Beer law appeared to be not lower than 7100 [cm²g^–1] against the value of about 3255 [cm²g^–1] reported in X-ray tables.     

影响石墨炉中特征量的某些因素研究

原子吸收光谱分析发展过程中,绝对分析一直是人们所期望解决的问题。Slavin等发展的稳温平台石墨炉(STPF),以及测量积分吸光度,为绝对分析提供了有效的实验技术条件。L′vov等首先从理论上计算了元素特征量。Frech等曾指出石墨炉沿管长的温度梯度是限制绝对分析的一个重要因素。张展霞等考虑塞曼效应计算了一些元素的特征量理论值,Co、Cr和V的特征量实验值与理论值之比大于L′vov的结果。本文采用3种不同     

石墨炉原子吸收光谱法绝对分析

石墨炉原子吸收光谱法(GFAAS)绝对分析近年来得到了较显著的发展,其主要原因是由于GFAAS中基体干扰问题获得了解决;用以描述GFAAS性能的特征质量MOE值相对稳定;以及用L’vov提出的计算MOT值的式子算出的32个元素的MOT值已比较接近其实验MOE值。大量数据表明完全有可能实现GFAAS绝对分析。     

成都市东郊(工业区)大气颗粒物及硫的分析

通过分析2006年上半年成都市东郊大气中总悬浮颗粒物及其中硫化物的含量和形态并结合酸雨问题阐述了成都市大气颗粒物的污染状况,并在搜集有关资料及实验的基础上,对成都东郊TSP中的硫化物的主要形态和含量作了初步的探讨,同时分析了硫化物与酸雨的联系,得出了结论并提出了建议。     

Effective L-Series Mass Absorption Coefficients for EDS

 Energy dispersive X-ray spectroscopy has insufficient resolution to separate the individual lines of low energy L-series peaks. However, the mass absorption coefficients for Lα and Lβ radiation differ significantly for elements with atomic numbers between 21 and 32. Effective mass absorption coefficients for the entire L-shell emission were determined by measuring the variation of the X-ray intensities emitted from pure element standards, as a function of the accelerating voltage, and fitting the experimental data with a theoretical curve using the XMAC software. These experimentally determined mass absorption coefficients were compared with average values calculated on the basis of the theoretical line intensities, taking into account the primary vacancy generation and the radiationless Coster-Kronig transitions.     

Atomic Absorption Spectrometry Analysis of Silicates by the Absorption Tube Technique

Abstract

By the combined use of the absorption tube technique and solvent extraction, determination of cadmium, cobalt, copper, iron, lead and nickel in silicate rocks was investigated.

Applicable concentration range was from 0.1 to 1.Oppm for all the elements except cadmium, for which the range was from 0.005 to 0.025ppm. The accuracy and recovery determined by the use of standard samples from the United States National Bureau of Standards and Geological Survey were satisfactory for practical purposes.     

Determination of Trace Elements in Aerosol Samples Collected on Polycarbonate Filters by Atomic Absorption Spectrometry

Abstract

The multi-element analysis of aerosol samples collected on polycarbonate filters and the wet digestion procedure in open vessel were investigated. The concentrations of Na, K, Ca, Mg and Zn were determined by flame atomic absorption spectrometry with a micro injection system while Cd, Pb, Cu, Ni and V were determined by graphite furnace atomic absorption spectrometry (AAS).

NIES N[ddot] 8 “Vehicle Exhaust Particulate” Certified Reference Material from the Japan Environment Agency was used to study the decomposition of the samples. Different treatments were applied in order to completely dissolve the aerosol samples. It was found that, from all the methods tested, attack with micro-quantities of HNO₃ and HCIO₄ in an air pressure digestion system was the best procedure for the determination of the elements by AAS.

The recommended method was appropriate for all elements and it was applied to real samples. Two nondestructive analytical techniques for the determination of Na, K, Ca, Mg, Zn and Pb have been compared with the proposed method: proton induced X-ray emission (PIXE) and neutron activation analysis (NAA). Results obtained by the application of these three techniques were similar.     

Isomerization of n-Hexane Over Platinum Ion-Exchanged Zeolite Beta

Zeolite Beta was synthesized from appropriate gels and crystallized under the controlled temperature and pressurized conditions. For isomerization of n-hexane, platinum ion-exchanged zeolite Beta exhibited high activity and selectivity for 2,2-dimethylbutane (2,2-DMB), 2,3-dimethylbutane (2,3-DMB), 2-methylpentane (2-MP) and 3-methylpentane (3-MP). As high as 72% of n-hexane conversion and 98% of product selectivity were obtained at 250°C, 1600 h^–1 for 20 min on stream. The influences of reaction temperature and space velocity were also studied. Pt/H-Beta zeolite was recommended as one of the promising catalyst for n-hexane isomerization due to its high activity and stability. The combined effect of the stronger acidity possessed by H-Beta and the dehydrogenation role played by Pt was believed to be responsible for the good catalytic performance of Pt/H-Beta.     

探讨二元颗粒混合物取样误差的新的数学模型

采用新的数学模型研究二元颗粒混合物的取样误差,首次提出了取样的逻辑质量单元的理论,探讨了逻辑质量单元的物理意义,建立了按质量取样的标准偏差的计算公式.应用颗粒药品二元混合物的取样实验,证实了该公式的正确性.     

气相色谱-质谱联用测定柴油机排气微粒中的可溶性有机组分

采用气相色谱-质谱联用技术(GC/MS)对柴油机排气微粒中的可溶性有机组分(SOF)进行了分离分析。SOF分析液样品采用超声提取法制取。GC条件为:SE-50型石英毛细管色谱柱(30 m×0.2 mm i.d.×0.2 μm）;程序升温：初始温度100 ℃,恒温2.0 min,以4.0 ℃/min升至160 ℃,再以8 ℃/min升至250 ℃,恒温31.75 min;汽化室温度260 ℃;载气为氦气,柱头压力45 kPa;进样量1 μL。MS条件为:电子轰击离子源,电子轰击能量70 eV;倍增器电压18