氟化电热蒸发／ICP—AES直接测定SiO2中痕量Fe

对氟化电热蒸发（ＦＥＴＶ）／ＩＣＰ－ＡＥＳ技术中元素的氟化蒸发行为，基体效应和粒度效应进行了考察，确定了杂质（Ｆｅ）与基体（Ｓｉ）分离的最佳实验条件，本法用于ＳｉＯ２中痕量Ｆｅ的直接测定，有灵敏，简便，试样消耗少和不需化学处理等优点。     

悬浮体进样/氟化电热蒸发(ETV)/ICP-AES直接测定二氧化钛粉末中痕量钇

以聚四氟乙烯(PTFE)悬浮体为氟化剂,悬浮体制样/氟化辅助电热蒸发(ETV)/ICP-AES直接测定TiO₂陶瓷粉末中痕量杂质钇;考察了影响基体和待测元素的蒸发过程的各种因素;对比研究了待测元素和基体的氟化蒸发行为;实现了基体和待测元素的预分离,显着降低了基体效应。本法的检出限为0.26μg/L,相对偏差为3.8%(n=5,c=0.5mg/L).     

乙酰丙酮在低温电热蒸发ICP-AES中的化学改进作用机理研究

近年来 ,低温蒸发技术的研究和应用引起了人们的重视 [1～ 3 ] .我们 [4]曾报道应用乙酰丙酮试剂作化学改进剂 ,于石墨管中低温 (～ 75 0℃ )蒸发铍的乙酰丙酮螯合物的 ETV-ICP-AES法 ,并用于人发中痕量铍的测定 .本文从机理上探讨了待测物 (铍或铬 )在石墨管中的蒸发及传输形式 ;研究了相应的乙酰丙酮螯合物的生成条件及主要影响因素 ;在此基础上得出在低温蒸发条件下相应的规律 .1　实验部分1.1　仪器装置　所用的 ICP-AES仪器、电热蒸发装置及它们之间的连接与文献 [1,4]相同 .紫外 -可见分光光度计 (日本岛津 UV-2 0 0 0 ) ,仪器…     

电热蒸发-电感耦合等离子体质谱(ETV-ICP-MS)技术中气溶胶传输效率研究进展

蒸发效率和传输效率是影响电热蒸发-电感耦合等离子体质谱(ETV-ICP-MS)技术分析性能的关键因素。综述有关气溶胶传输效率的研究进展,在归纳常用的传输系统评价方法的基础上,重点对影响气溶胶传输效率的电热蒸发装置的改进、蒸发过程的探讨、基体改进剂的选择等研究现状进行评述。有关ETV蒸发过程中基体干扰的作用机制仍有待进一步系统研究,这对于校正策略的优化、新型校正技术的创新与集成具有重要的理论指导意义,可推动ETV-ICP-MS在地质、环境、生物等学科的更广泛应用。     

氟化辅助电热蒸发/ICP-AES直接测定氧化铝粉末中痕量杂质钇

报道了以聚四氟乙烯（PTFE）悬浮体为氟化剂,悬浮体制样／氟化辅助电热蒸发（ETV）／ICP －AES直接测定两种AI2O3粉末样品中痕量杂质钇。考察了影响基体和待测元素蒸发过程的各种因素;对比研究了待测元素和基体的氟化蒸发行为。在优化实验条件下,方法的检出限为0．1μg/g,相对标准偏差为5．6％（n=5,c=8g/L悬浮体）。并与溶样法气动雾化（PN）－ICP－AES的分析结果进行了对比。本法简便、灵敏、无需任何化学前处理,可用于相关陶瓷生产过程中的质量控制。     

悬浮体进样／氟化电热蒸发（ETV）／ICP—AES直接测定二氧化钛 …

以聚四氟乙烯（ＰＴＦＥ）悬浮体为氟化剂,肖体制样／氟化辅助电热蒸发（ＥＴＶ）／ＩＣＰ－ＡＥＳ直接测定ＴｉＯ２陶瓷粉末中痕量杂质钇考察了影响基体和等测元素的蒸发过程的各种因素,对比研究了待测元素和基体的氟化蒸发行为,实现了基体和待测元素的预分离,显著降低了基体效应。本法的检出限为０．２６μｇ／Ｌ。相对偏差为３．８％（ｎ＝５,ｃ＝０．５ｍｇ／Ｌ）。     

氟化电热蒸发／电感耦合等离子体原子发射光谱中的基体效应研究

本文系统研究了氟化电热蒸发／电感耦合等离子体原子发射光谱（ＥＴＶ－ＩＣＰ－ＡＥＳ）测定难熔元素的基体效应。与常规气动雾化（ＰＮ）－ＩＣＰ－ＡＥＳ中的基体效应比较，氟化ＥＴＶ－ＩＣＰ－ＡＥＳ中的基体效应更小。对难熔基体元素，由于基体和待测元素与氟化剂之间的竞争反应，随着基体浓度的增加，待测元素谱线强度降低；对常见基体元素，由于热循环中基体与待测元素之间的选择挥发，对待测元素的蒸发和传输过程无明显影响     

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。     

电热蒸发钨丝在线捕获原子荧光光谱法直接测定菠菜中痕量镉

利用钨丝(TC)常温下特异性捕获镉(Cd)消除基体干扰,泡沫碳材料电热蒸发器串联原子荧光光谱仪,实现了固体直接进样测定菠菜鲜样中痕量Cd。研究表明,泡沫碳电热蒸发器性能稳定,样品个体差异对测定无影响;经液氮冷冻粉碎的菠菜鲜样均匀度良好,Pauwels公式估算最小取样量为16.3 mg,满足仪器微量进样要求。采用灰化(50 W保持50 s,70 W保持80 s)、蒸发(70 W保持30 s)过程分离,Ar-H2(9∶1,V/V)载气流速为600 mL/min时,方法检出限可达0.2μg/kg,回收率为90.1%~106.1%,RSD小于10%,分析时间少于5 min,常见金属元素和有机物质对测定无干扰,且与微波消解石墨炉原子吸收光谱法结果无显著性差异(p>0.05)。     

聚四氟乙烯悬浮体氟化剂的ETV—ICP—AES测定氧化镧中钇的研究

采用PTFE悬浮体为氟化剂,成功地将易生成难熔碳化物的稀土元素从石墨炉中完全蒸发,并用ICP-AES进行测定。检出限为10~(10)～10～(12)g,比常规ETV—ICP-AES的检出限改善两个数量级;消除了记忆效应,相对标准偏差优于5％。本文还讨论了影响氟化蒸发的主要因素,并将此法用于La_2O_3中杂质钇的测定。     

用ETV-ICP-MS研究Cr、Ni、Zr、Nb、Yb在石墨炉中的蒸发/原子化机理

本文以电热蒸发电感耦合等离子体质谱（ETV-ICP-MS）为手段,探讨了Cr、Ni、Zr、Nb和Yb在石墨炉中的蒸发/原子化机理;比较了不同化学改进剂存在条件下,Cr、Ni、Zr、Nb和Yb的蒸发行为和在石墨炉原子吸收（GFAAS）中的原子化行为;考察了石墨炉温度和ICP功率等实验参数对上述元素发射强度及轮廓的影响.结果表明,Pd和Mg化合物的存在对Cr、Ni、Zr、Nb和Yb的蒸发/原子化行为没有明显的化学改进作用;然而,以聚四氟乙烯（PTFE）为化学改进剂时,可显著改善Cr、Ni、Zr、Nb和Yb的蒸发行为,避免难熔碳化物的形成,降低待测物的蒸发温度;对Cr和Ni的GFAAS信号强度略有增强;但是,由于Yb、Nb和Zr氟化物的离解键能很高,难以离解/原子化,PTFE的存在反而降低了Yb、Nb和Zr在GFAAS中的信号强度.     

Vaporization and atomization of the platinum group elements in the graphite furnace investigated by electrothermal vaporization-inductively coupled plasma-mass spectrometry

The mechanisms by which the platinum group elements (PGEs) are vaporized in the graphite furnace have been investigated using electrothermal vaporization-inductively coupled plasma-mass spectrometry (ETV-ICP-MS). The results suggest that live of these elements (Ru, Rh, Pd, Ir and Pt) are reduced to their metallic state in the graphite furnace and then vaporized by direct sublimation of the metal. For Os, the vaporization mechanism is different. In the presence of HNO₃, two distinct vaporization processes are observed. Volatile oxides of Os are released at low temperatures, but some of this oxide is reduced to relatively involatile Os metal which is then vaporized when the temperature is increased above 2000°C. The addition of TeCl₂ chemical modifier was found to have minimal effect on the vaporization mechanism and sensitivity for determination for five of the PGEs. For Os, however, the analytical sensitivity and limit of detection was improved when Te modifier was used in conjunction with a lower vaporization temperature of 1400°C. Optimum conditions for the determination of the PGEs by ETV-ICP-MS are reported, along with their absolute limits of detection; these range from 0.015 pg for Ir to 0.25 pg for Os.     

Atomic Emission Spectrometry of Inductively Coupled Plasma with Sample Introduction by Electrothermal Vaporization

A system is described in which a graphite furnace electrothermal vaporization device is employed for the introduction of microlitre liquid sample into an inductively coupled argon plasma. The technique provides a picogram detection limit and an adequate precision with a relative standard deviation of 4%. Mechanism of analyte condensation in transport process is explored. As an application, the technique combined with DDTC/CCl4 extraction is used to enrich and determine non- rare earth impurities in highly pure La2O3.     

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.     

Vaporization of Pb,As and Ga alone and in the presence of Pd modifier studied by electrothermal vaporization-inductively coupled mass spectrometry

Inductively coupled plasma mass spectrometry (ICP-MS) with electrothermal vaporization (ETV) was used to study the processes taking place in a graphite furnace for atomic spectroscopy. Monitoring of carbon release during the pyrolysis stage provided information on the solid-state reduction processes. Among three carbon species studied (¹²C, ¹³C and ²⁸CO), ¹³C was found to be the most suitable. Gallium and arsenic oxides practically do not reduce during the pyrolysis stage. According to the data on carbon release, two reduction processes of lead species (at about 690–915 and > 1000 °C) were found to take place in the furnace. Two separate peaks of Pb (at the end of the pyrolysis stage and in the vaporization stage) were observed, probably related to vaporization of unreduced lead oxide and elemental Pb, respectively. A pre-reduced palladium modifier suppresses the low-temperature Pb losses so that the high-temperature Pb peak is increased. In the absence of modifier, a gaussian-shaped As signal was formed only if small arsenic masses were introduced into the vaporizer. Increase of the arsenic mass resulted in formation of a pronounced plateau after the peak, in spite of the very high vaporization temperature applied (2500 °C). In the presence of pre-reduced palladium modifier, a gaussian-shaped As signal was formed already at 1700 °C with a 4–15-fold increase in sensitivity depending on the analyte mass. The palladium modifier apparently prevents strong interaction of arsenic with graphite. The obtained data support very high potential of ETV-ICP-MS for detailed investigation of processes occurring in graphite furnaces used in analytical atomic spectroscopy, especially during the pyrolysis stage.     

Vaporization of indium nitrate in the graphite tube atomizer in the presence of chemical modifiers

The CCD spectrometer coupled with the graphite tube furnace was employed to investigate the vaporization of micrograms of In (as nitrate). Fifty absorption spectra between 200 and 475 nm were collected during 10 s while the tube temperature increased from 700 to 2600–2700 K. The vaporization was carried out in the pyrocoated, Ir-sputtered and Ta-lined tubes in the presence of Cu, Co, Ni, Pd and Mg nitrates, sodium tungstate, ascorbic acid and ammonium hexachloroiridate monohydrate after thermal pretreatment. In the pyrocoated tube the vaporization of In occurred at 1350–1550 K with fast evolution of molecular vapor. The observed broad bands with maxima at 225, 290 and 275 nm were attributed to In₂O and InO, according to their thermal behavior. Cu, Co, Ni, Pd, Ir modifiers, Ta-lining and Ir sputtered surface suppressed the release of In oxides and induced the delayed appearance of In atomic lines simultaneous with a broad band at 205 nm, tentatively attributed to In dimer. Tungsten caused faster and more complete reduction of In oxide than carbon. Indium oxide bands were substituted between 1100 and 1350 K by a band at 244 nm assigned to gaseous tungsten oxide. Ascorbic acid caused the decrease of indium oxide fraction in gas phase. The presence of MgO in the tube led to the decrease of the band at 205 nm. The vaporization of micrograms of Cu, Co, Ni, Pd and MgO in the pyrocoated tube caused the appearance of absorption and emission continuum, superimposed to In atomic lines at temperatures above 1550 K. This effect had been earlier explained as induced by exothermal interaction of the vaporized substance with carbon. SEM observations of Ir deposits on the graphite surface confirmed the interaction of Pt group metals with carbon at high temperature. A similar effect is advanced for other metal modifiers.     

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.     

电热蒸发进样电感耦合等离子体原子发射光谱（ETV－ICP－AES）联用技术研究

本文采用国产部件组装了一套ＥＴＶ－ＩＣＰ－ＡＥＳ仪器体系，对装置的连接及操作参数进行优化。深入系统地考察了分析物的蒸发过程和传输过程，提出了难熔元素的蒸发和传输机理。研究了ＥＴＶ－ＩＣＰ－ＡＥＳ中基体效应，提出了以聚四氟乙烯为氟化剂，氟化辅助ＥＴＶ－ＩＣＰ－ＡＥＳ测定难熔元素的新方法，应用于环境和生物标样中痕量元素分析，获得满意结果。     

Dynamics of the Spatial Distribution of Atomic and Molecular Absorbing Layers in the Electrothermal Vaporization and Electrostatic Precipitation of an Analyte in an Atomizer

An experimental device was described for atomic absorption analysis with the electrothermal vaporization of the initial sample followed by the condensation of vaporization products and the electrostatic precipitation of the resulting aerosol in the secondary atomizer. Working conditions ensuring the maximum transfer of the sample to the atomizer were determined. The dynamics of the spatial distribution of the absorbing atomic and molecular layers was studied for atomization in a graphite furnace after the direct sample injection and electrostatic precipitation. The contribution of some physicochemical processes to the formation of the structure of cadmium atomic layers was assessed for different methods of sample injection into the atomizer. It was shown that an additional vaporization–condensation step significantly decreases the level of nonselective absorption and smoothes its gradients.     

Vaporization and thermodynamic properties of the PbO-V2O5 system

The vaporization of individual lead and vanadium oxides and a wide range of compositions of PbO-V₂O₅ melts has been studied. The thermodynamic characteristics of the PbO-V₂O₅ system have been determined, PbO-V₂O₅ melts show negative deviations from the ideal behavior because of the formation of thermally stable compounds in their condensed phase. For gaseous lead vanadate PbV₂O₆, the thermodynamic functions have been calculated and the standard enthalpies of formation and atomization have been determined.