石墨炉原子吸收光谱中海水的背景吸收研究

由于海水的成分复杂,含盐量高,给用石墨炉直接测定其中的痕量杂质带来许多困难^[1]。Sturgeon等用预先分离的方法来克服干扰^[2]。为了进行直接测定,研究海水背景吸收的来源、特点和消除方法是重要的。海水背景吸收的波长特性和在石墨管内蒸发行为的研究表明,海水的背景吸收主要来自氯化钠。时间特性的研究表明,背景吸收的时间分布及背景峰高与原子化阶段的加热方式和原子化温度有关。作者还研究了基体改进。剂和其它减小背景吸收的方法。     

恒温石墨炉中基体对钾和镉的影响

电热原子化原子吸收分析易受基体的干扰,使得准确度的提高受到限制.有关减少和消除这个影响已有报导^[1-6]。Czobik等^[6]人曾指出,为减少和消除基体的干扰,应设计一种具有时间和空间上等热条件的石墨炉。恒温石墨炉有上述的性质,用它作原子化器能消除和减少基体的影响。     

炸药爆轰合成纳米石墨的红外光谱研究

石墨是碳材料中最常见的结晶状态,它具有耐高温、抗腐蚀、自润滑、无毒及价格低廉等特点,广泛应用于润滑剂和添加剂等方面^[1].由于高纯纳米石墨粉在某些高新技术领域中有较好的应用前景,近些年来得到开发和应用,如制成复合导电材料、吸波材料及储氢材料等^[2].以前有学者用纳米金刚石粉加热相转变^[3]和高能球磨^[4,5]的方法制备了纳米石墨,在制备碳纳米管时也有石墨的纳米粒子生成^[6].但用这几种方法制备纳米石墨,既费时又消耗较大能量,成本非常高.     

电热蒸发进样/电感耦合等离子体原子发射光谱的蒸发过程研究

本文考察了电热蒸发进样 ETV/ICP-AES 技术中蒸发电流对不同挥发性元素的信号强度及峰形的影响;探索了蒸发器体积及其结构对分析物蒸发行为和信号的影响;本文还探索了平台技术在 ETV-ICP-AES 中的应用。并相应得出了一些有益的结论。     

静电纺丝法制备NiO纳米纤维及其表征

纳米级NiO因具有优良的催化和热敏等性能而被广泛用于催化剂^[1]、电池电极^[2,3]、光电转化材料^[4～6]、电化学电容器^[7～8]等诸多方面.迄今,已成功地制备出N iO的纳米颗粒^[9]、纳米线^[10]及纳米薄膜^[11],但是对于具有准一维结构的NiO纳米纤维的制备及性能研究尚未见报道.     

X射线荧光光谱法检测高炉壁夹杂料中主次量成分时残碳的准确测定和去除

<正>高炉壁夹杂料是入炉料与原生耐火材料在高温下充分反应、磨合,逐渐在高炉炉缸、炉壁及炉底等位置形成的矿相侵蚀层^[1]。分析各矿相侵蚀层中主次量元素分布规律,可为了解工况参数变化对高炉侵蚀的影响^[2],高炉结构设计以及高炉维修等提供技术指导。高炉壁夹杂料中含有碳、铁、镁、铝、硫、磷、钾、钠、铅、砷、铜、钙、钛、硅和锌等元素,成分较多且配比不明确,常见的滴定法、分光光度法、原子吸收光谱法(AAS)、电感耦合等离子体原子发射光谱法(ICP-AES)等因受检测范围或检测时间限制,难以满足高炉壁夹杂料批量分析的要求^[3]。X射线荧光光谱法(XRFS)具有方便、快捷、检测元素多、周期短等特点^[4],但在采用XRFS分析高炉壁夹杂料样品时,焦炭在炉内未完全燃烧产生的残碳会腐蚀熔融制样的铂-金坩埚^[5],     

两种卟啉化合物在Ag溶胶表面的紫外-可见吸收光谱和表面增强拉曼散射光谱研究

表面增强拉曼散射(SERS)自1974年被Fleischmann等^[1]发现以来,日益受到人们的重视.通过SERS谱图分析,可以获得物质结构及其与基体作用的信息.由于SERS可使拉曼信号增强10⁵~10⁶倍^[2],并且在某些情况下银胶还能使表面吸附质的荧光猝灭^[3,4], SERS常用来检测一些普通拉曼光谱难以检测的样品和考察界面络合物的形成.     

XRD谱研究扩散控制的固-固相反应

很多分子固体和低维固体在室温或低热温度条件下可发生固相反应^[1,2],甚至可以在短时间内完成^[3,4].我们已成功地用低热固相合成法合成了200多个化合物,其中大多数为结构新颖的原子簇化合物^[5～7].     

聚乙烯醇载银海绵的制备及界面光热驱动水蒸发性能

利用光热材料的太阳能水蒸发技术是一种绿色、 环保地解决淡水资源短缺的重要技术, 但光热材料的制备成本、 蒸发效率和热损失等因素限制了其推广应用. 本文采用一锅法制备了聚乙烯醇载银海绵(AgNPs/PVA)太阳能界面蒸发器, 并研究了AgNPs含量对AgNPs/PVA在太阳能驱动水蒸发过程中光热性能的影响. 研究结果表明, 当AgNPs的质量为PVA的10%时, 制备的AgNPs/PVA在1 kW/m ²的太阳光强度下具有最优的蒸发速率, 水蒸发速率可达1.62 kg?m ^?2?h ^?1, 为纯水(0.42 kg?m ^?2?h ^?1)的3.9倍. 本文制备的AgNPs/PVA具有制备工艺简单、 亲水性能优良和蒸发性能良好的特点, 在太阳能驱动水蒸发领域具有较大的应用前景.     

微波消解-微波等离子体炬原子发射光谱法测定无铅汽油中痕量铅的研究

四乙基铅作为一种良好的抗爆添加剂,曾广泛用于汽油生产中,但由于四乙基铅有很强的毒性,目前国际上已停止生产和使用车用含铅汽油,因此在生产车用无铅汽油时严格控制和准确测定铅的含量十分必要.迄今,测定汽油中铅含量的常用方法是铬酸盐容量法^[1]、一氯化碘法^[2]、X射线光谱法^[3]、分光光度法^[4,5]、原子吸收光谱法^[6]和等离子体光谱法^[7].这些方法或操作烦琐,测定时间较长^[4],或灵敏度低^[1～3],或测定误差较大,且在测试中需使用毒性较大的四乙基铅^[5],或所需的氯化甲基三辛基铵不易购买^[6],或处理过程繁琐,且仪器设备昂贵^[7].因此,建立一种简便、快速、灵敏、准确和无毒副作用的测定无铅汽油中痕量铅的方法已显得十分迫切.近年来发展的微波等离子体炬原子发射光谱法^[8]已有商品化仪器问世^[9].本文利用微波等离子体炬原子发射光谱仪研究了无铅汽油中痕量铅的测定方法,并提出用微波消解法预处理无铅汽油样品,将微波消解技术与微波等离子体炬原子发射光谱法相结合,建立了简便、快速、灵敏、准确和无污染的测定无铅汽油中痕量铅的新方法.     

Comparative Studies on Chemical Modification by Diethyldithiocarbamate for ETV-ICP-OES and ETAAS Determination of Chromium and Nickel

The chemical modification of diethyldithiocarbamate (DDTC) in electrothermal vaporization inductively coupled plasma optical emission spectrometry (ETV-ICP-OES) and in electrothermal atomic absorption spectrometry (ETAAS) was comparatively investigated. The experimental results indicated that the formation of Cr- and Ni-DDTC chelates enhanced significantly the emission signals of Cr and Ni in ETV-ICP-OES, but decreased the absorption signal of Cr and Ni in ETAAS. The different role of DDTC in ETV-ICP-OES and ETAAS was attributed to the different functions of the graphite furnace in the two techniques. The graphite furnace was used as both a vaporizer and an atom-vessel for analytes in ETAAS, but only used as a vaporizer for the sample in ETV-ICP-OES. Thermal gravimetric analysis of Cr- and Ni-DDTC chelates and UV-Vis analysis of the sample vapor collected in CHCl₃ after vaporization of their chelates from the graphite furnace indicated that the analytes were vaporized and transported into ICP as their chelates. In addition, the vaporization mechanism of Cr and Ni was also briefly discussed.     

Analyte transport efficiencies in electrothermal vaporization for inductively coupled plasma mass spectrometry

A modified graphite furnace for solid-sampling atomic absorption spectrometry as an electrothermal vaporizer (ETV) was coupled to a Perkin-Elmer/Sciex ELAN 6000 ICP mass spectrometer. The integrals obtained from electrothermal vaporization of aliquots containing As, Cd, Cu, Co, Fe, Mn, Pb, Se, and Zn were compared with those obtained from pneumatic nebulization of the same aqueous standard solution. The pneumatic nebulizer was calibrated by weighing the mass of aqueous aerosol trapped on a filter. With "wet plasma" conditions maintained also for measurements with the ETV and reference signals for analyte signals obtained with the calibrated pneumatic nebulization, the transport efficiency of the ETV system, e.g. the ratio of the analyte amount introduced into the plasma to that amount dosed into the vaporizer, was determined. The transport efficiency of two different tube and interface designs has been evaluated. Investigations with and without the use of trifluoromethane as reactive gas, with different furnace heating rates, and with varying gas flows were performed. In general, the tube equipped with a nozzle led to generally higher transport efficiency than the standard tube. Without trifluoromethane transport efficiencies ranged from 10% to 35% with the standard tube and from 15% to 50% with the nozzle-type tube. With addition of 2 mL min(-1) trifluoromethane to the argon flow of 400 mL min(-1) through the tube, transport efficiencies from 20% to 70% and from 70% to 100% were achieved with the standard and nozzle-type tubes, respectively.     

Efficiency of sample introduction into inductively coupled plasma by graphite furnace electrothermal vaporization

A laboratory constructed graphite furnace electrothermal vaporizer (GF-ETV) was used for studying transport efficiencies. This device enables collection of the vaporization products that exit the central sampling hole of the horizontal graphite tube. For determination of the transport efficiency between the GF-ETV and the ICP-torch three methods were tested: (1) deposition of the aerosol particles and the vapour of certain elements by mixing the vaporization product with supersaturated steam and subsequent condensation (direct method); (2) dissolution of the deposited sample fraction from the interface components (indirect method); and (3) calculation from line intensities when applying GF-ETV and pneumatic nebulization sample introduction methods using mercury as a reference element. The latter, `mercury reference method' required 100% transport efficiency for mercury with the ETV, which could be approximated with the use of argon as carrier gas (without halocarbon addition). With a 200 cm³/min flow rate of internal argon in the graphite tube, the transport efficiency was between 67 and 76% for medium volatility elements (Cu, Mn and Mg) and between 32 and 38% for volatile elements (Cd and Zn). By adding carbon tetrachloride vapour to the internal argon flow, the transport efficiency increased to 67–73% for the five elements studied.     

Vaporization and atomization of uranium in a graphite tube electrothermal vaporizer: a mechanistic study using electrothermal vaporization inductively coupled plasma mass spectrometry and graphite furnace atomic absorption spectrometry

The mechanism of vaporization and atomization of U in a graphite tube electrothermal vaporizer was studied using graphite furnace atomic absorption spectrometry (GFAAS) and electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS). Graphite furnace AAS studies indicate U atoms are formed at temperatures above 2400°C. Using ETV-ICP-MS, an appearance temperature of 1100°C was obtained indicating that some U vaporizes as U oxide. Although U carbides form at temperatures above 2000°C, ETV-ICP-MS studies show that they do not vaporize until 2600°C. In the temperature range between 2200°C and 2600°C, U atoms in GFAAS are likely formed by thermal dissociation of U oxide, whereas at higher temperatures, U atoms are formed via thermal dissociation of U carbide.The origin of U signal suppression in ETV-ICP-MS by NaCl was also investigated. At temperatures above 2000°C, signal suppression may be caused by the accelerated rate of formation of carbide species while at temperatures below 2000°C, the presence of NaCl may cause intercalation of the U in the graphite layers resulting in partial retention of U during the vaporization step. The use of 0.3% freon-23 (CHF₃) mixed with the argon carrier gas was effective in preventing the intercalation of U in graphite and U carbide formation at 2700°C.     

Analyte transport efficiencies in electrothermal vaporization for inductively coupled plasma mass spectrometry

A modified graphite furnace for solid-sampling atomic absorption spectrometry as an electrothermal vaporizer (ETV) was coupled to a Perkin–Elmer/Sciex ELAN 6000 ICP mass spectrometer. The integrals obtained from electrothermal vaporization of aliquots containing As, Cd, Cu, Co, Fe, Mn, Pb, Se, and Zn were compared with those obtained from pneumatic nebulization of the same aqueous standard solution. The pneumatic nebulizer was calibrated by weighing the mass of aqueous aerosol trapped on a filter. With “wet plasma” conditions maintained also for measurements with the ETV and reference signals for analyte signals obtained with the calibrated pneumatic nebulization, the transport efficiency of the ETV system, e.g. the ratio of the analyte amount introduced into the plasma to that amount dosed into the vaporizer, was determined. The transport efficiency of two different tube and interface designs has been evaluated. Investigations with and without the use of trifluoromethane as reactive gas, with different furnace heating rates, and with varying gas flows were performed. In general, the tube equipped with a nozzle led to generally higher transport efficiency than the standard tube. Without trifluoromethane transport efficiencies ranged from 10% to 35% with the standard tube and from 15% to 50% with the nozzle-type tube. With addition of 2 mL min^–1 trifluoromethane to the argon flow of 400 mL min^–1 through the tube, transport efficiencies from 20% to 70% and from 70% to100% were achieved with the standard and nozzle-type tubes, respectively.     

Analyte transport efficiency with electrothermal vaporization inductively coupled plasma mass spectrometry

Reported are results for the quantitative determination of absolute transport efficiency in electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) for the Perkin-Elmer HGA-600MS electrothermal vaporizer. The absolute transport efficiencies for Mo, In, Tl and Bi were determined using experimental conditions typical of those applied to real analysis by ETV-ICP-MS. Experiments using an on-line filter trapping apparatus indicated that particles produced by the ETV device were smaller than 0.1 μm in diameter. The nature and condition of the ETV graphite surface, the length of the transfer tube, and the effect that diluted seawater and palladium modifiers have on analyte transport efficiency were investigated. Transport efficiency was comparable for all elements studied and was enhanced with previously used, rather than new, graphite tubes and when seawater and palladium carriers were present. When analyte was vaporized without carrier from a new graphite tube, the transport efficiency to the plasma was approximately 10%. Approximately 70% of the total amount of analyte vaporized was deposited within the ETV switching valve, 19% onto the transfer tubing and 1% onto the components comprising the torch assembly. These conditions represent the `worst case scenario', with analyte transport to the plasma increasing to approximately 20% or more with the addition of carrier.     

Direct atomic absorption determination of mercury in drinking water and urine using a two-step electrothermal atomizer

A new method was developed for the direct electrothermal atomic absorption determination of mercury in drinking water and urine using double vaporization in a two-step atomizer with a purged vaporizer. In this method, a sample is placed in the vaporizer of a two-step atomizer, dried, and vaporized. The sample vapor is transferred to an unheated atomizer cell with a flow of argon and trapped by the inner surface of cell walls. This procedure can be performed repeatedly to preconcentrate mercury in the atomizer cell. Next, a portion of the sample transferred to the inner surface of the atomizer cell is revaporized and atomized by heating the atomizer cell of the two-step atomizer with a purged vaporizer, and the atomic absorption of mercury is measured. It was found that the degree of mercury transfer and trapping is as high as 100% at sufficiently high temperatures of primary vaporization, regardless of the material of the inner surface of the atomizer cell. The detection limits for mercury were 0.24 or 0.024 µg/L for drinking water at a sample volume of 100 µL using a single sample transfer or the procedure repeated ten times, respectively, and 2.0 µg/L for urine at a sample volume of 20 µL and a single sample transfer. The accuracy of the results was confirmed by the analysis of certified mercury samples and samples with known additives.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 1, 2005, pp. 45–51.Original Russian Text Copyright © 2005 by Vilpan, Grinshtein, Akatov, Gucer.     

A two-step atomizer system using a transversely heated furnace with Zeeman background correction: Design and first solid sampling applications

A two-step-atomizer consisting of a transversely heated graphite atomization tube and a movable vaporizer graphite cup is described. The atomizer is placed between the poles of an electromagnetic field providing longitudinal Zeeman-effect background correction capability. The tube and the cup are heated by independent power supplies enabling the performance of atomic absorption measurements at temporally and spatially isothermal conditions. The design of the vaporizer provides several advantageous features including direct introduction of solid and liquid samples with extremely low contamination risk and a sampling volume of up to 105 μl. The performance of this system was assessed by analysis of the bovine liver NIST SRM 1577b and of a well characterized titanium dioxide material. Calibration curves for quantification were recorded by using aqueous standards. In comparison of the results obtained by this method with the certified values and with the results of independent methods, excellent to reasonable agreement was achieved. For the elements Fe, K, Mg, Mn, Na and Zn in titanium dioxide, the achievable limits of detection were between 60 pg g^− 1 (Mg) and 0.7 ng g^− 1 (Fe).     

Atomic and molecular spectra of vapors evolved in a graphite furnace. Part 5: gallium,indium and thallium nitrates and chlorides

The vaporization behavior and vapor spectra of Ga, In and Tl nitrates and chlorides in the tube furnace was investigated using an UV spectrometer with CCD detector. Fifty spectra in the wavelength range of 200–475 nm were collected in each experiment during the vaporization step, with temperature increase from 473 to 2673 K. The vaporization patterns were compared for the pyrocoated, non-pyrocoated graphite tubes, and Ta-lined tubes. Nitrate and chloride aqueous solutions and chloride slurries in chloroform were used to distinguish the impact of hydrolysis on the vaporization behavior of these chlorides. The spectra of oxygen and chlorine containing molecules, presumably of suboxides, chlorides and dichlorides were identified upon variation of the experimental conditions. The release of suboxide vapors due to the reduction of oxides by carbon was promoted after the decomposition of nitrates. The presence of other elements on the vaporization surface, or the isolation of the sample from the graphite surface by Ta-lining, impeded the vapor release and reduced the intensity of molecular bands. Adsorption of chlorine onto graphite caused a decrease of chloride and dichloride bands. The suboxide bands were observed in the spectra of Ga and In chlorides introduced in the tube as aqueous solutions, due to partial hydrolysis.