石墨炉原子吸收光谱法的石墨管表面的难熔碳化物涂覆处理

廿余年来,电热石墨炉已发展成为应用较为广泛的一种最有代表性的电热原子化器。关于电热石墨炉原子吸收光谱法的许多研究报告都指出石墨管的表面状态与测定灵敏度、检出限、精密度、记忆效应、管     

电热原子吸收光谱分析中的干扰及其消除和控制(一)

引言1.1 概述虽然化学火焰已广泛应用于原子光谱分析,但是仍然存在一些缺点。基本因素之一是其原子化效率较低。因此,研究了几种另外的基于辉光放电、稳定电弧、炉和丝的技术作为原子化的手段,其目的是在较小的体积中得到较高的原子浓度。用于原子吸收测量的在高温石墨炉中将试样电热原子化的方法已显示出最广阔的前景。它兼顾了非常高的原子化效率和适应固体试样或通常需要一些预处理的试样的能力。另外的好处是可以在受控的气氛中工作。然而,与火焰原子化法相比,在电热原子化器中     

琥珀试样中痕量元素的直接同时测定--氟化辅助电热蒸发等离子体光谱法

本文报道了以聚四氟乙烯（ＰＴＦＥ）悬浮液为化学改进剂,采用悬浮体进样电热蒸发电感耦合等离子体原子发射光谱法（ＥＴＶ－ＩＣＰ－ＡＥＳ）直接同时测定琥珀样品中痕量元素的新方法。对石墨炉和ＩＣＰ之间的气体流路接口进行了改进;详细研究了载气／辅助载气流量、蒸发温度、蒸发时间及信号记录时间等因素对待测物信号强度的影响。在优化实验条件下,本法同时测定琥珀试样中痕量Ａｌ、Ｃａ、Ｃｒ、Ｃｕ、Ｆｅ、Ｍｇ、Ｍｎ、Ｎｉ     

人参皂甙中微量As测定

微量As测定一般多采用石墨炉原子吸收法,电热—氢化物原子吸收法和原子荧光法。三种方法灵敏度大致相同,但电热—氢化物原子吸收法具有干扰小的特点。人参皂甙中As主要来源于农药和化肥的污染,最高允许量小于10ppm。否则会造成对人体的危害。国内这方面的分析工作尚未见报导。     

石墨炉原子吸收法测钡时石墨管性能的探讨

近年来,随着石墨炉原子吸收分析技术的发展和应用,使人们越来越深刻地认识到石墨管的性能对石墨炉原子吸收分析起着重要的作用,它直接影响分析方法的灵敏度、检出限和准确度。因此作者在进行石墨炉原子吸收法测钡时,同时观察了普通石墨管、热解涂层石墨管和全热介石墨管的性能,并将所得实验结果作了全面的比较。     

石墨炉原子吸收光谱分析的理论基础 Ⅱ.石墨炉中原子形成的机理

近年来,随着石墨炉原子吸收分析技术的发展及其在冶金、地质、医学、生物和环境试样分析中的广泛应用,遇到了很多饶人兴趣的问题。其中最引人注目的就是石墨炉中原子形成机理的研究。深入研究石墨炉中进行的高温化学反应,阐明原子形成的机理有     

平台石墨炉原子吸收法测定血清铬

介绍了用平台石墨炉原子吸收法测定血清铬的方法，详述了测定的实验条件，比较了平台石墨炉原子吸收法与火焰法、普通石墨管石墨炉原子吸收法测定血清铬的差异，提出以硝酸镁为基体改进剂，血清经酸处理后可使测定结果几无干扰，并测定了７５名健康体检者，其参考范围为０．４７６￣０．５９２μｇ／Ｌ。     

平台石墨炉原子吸收法测定血清铬

介绍了用平台石墨炉原子吸收法测定血清铬的方法，详述了测定的实验条件，比较了平台石墨炉原子吸收法与火焰法、普通石墨管石墨炉原子吸收法测定血清铬的差异，提出以硝酸镁为基体改进剂，血清经酸处理后可使测定结果几乎无干扰，并测定７５名健康体检者，其参考范围为０．４７６－０．５９２μｇ／Ｌ。     

石墨炉原子吸收法测定香根草中痕量Pb、Cd、Cu

采用石墨炉原子吸收法直接测定了香根草中重金属的含量,通过一系列实验,确定了石墨炉法测定Pb、Cd、Cu的最佳灰化温度和原子化温度,考察了精密度和回收率。结果表明,该法操作简单快捷,样品用量少,灵敏度高,稳定性好。     

石墨炉原子吸收法测定岩石中锡

石墨炉原子吸收法测定锡多用于金属试样分析。池田等曾以镧作共沉淀剂,在氨性介质中使锡共沉淀,然后于1N硝酸中,利用镧的增感效应,以石墨炉原子吸收法测定了金属锌和铜中锡。本文拟定了石墨炉原子吸收测定岩石中锡的方法,以钼酸铵作添加剂,不仅可以增强待测元素锡的吸收信号,还可以抑制某些共存元素的干扰,可不经分离直接测定岩石试样中0.2～0.00005%的锡。方法简便,精密度和准确度均令人满意。本方法也可应用于生物组织及其它试样中锡的测定。     

流动注射氢化物石墨炉原子吸收法的应用研究 Ⅰ.——实验装置与分析性能

氢化物石墨炉联用技术的原理是先在较低温度下将氢化物蒸气通入石墨炉并分解沉积于石墨管的内表面,然后再在高温下原子化。该法能明显提高灵敏度,消除液相和气相干扰。本文采用自制的半自动氢化物石墨炉进样系统及流动注射氢化物发生器,直接在普通石墨炉上进行氢化物石墨炉分析,研究了部分元素的测定条件,建立的方法操作方便,灵敏度高,耗样少,线性范围宽,是一种值得推广的新方法。     

石墨炉原子吸收光谱法测定碘化铯晶体中铊

采用平台石墨炉原子吸收光谱法测定了碘化铯晶体中铊。研究了碘化铯对钯－硝酸镁基本改进剂中铊吸光度影响,用预混合钯－硝酸镁和样品溶液,由于在碘化物溶液中易析出金属钯而使测定结果降低。用样品溶液和基体改进剂分别加入到石墨炉中的标准加入法可得到满意的结果。     

测定鱼中痕量硒的横向石墨炉原子吸收分光光度法

应用加拿大Aurora -1000型横向石墨炉原子吸收分光光度计测定鱼中痕量硒,优化了样品消化条件和待测元素的各项测定参数 ,并对横向石墨炉和纵向石墨炉在同等条件下测定硒作了较为详尽的比较。用该法对实际样品进行了测定,获得满意结果。     

Status and future prospects for use of the graphite furnace for elemental trace analysis of liquids and solids

Summary An overview of the versatility and use of the graphite furnace for elemental trace analysis of liquids and solids using spectrochemical detection is presented. The analytical performance of conventional graphite furnace atomic absorption spectrometry is compared to other popular state of the art spectrochemical techniques with respect to detection power, precision, sample compatibility and throughput. Some applications of the graphite furnace to practical problem solving in trace analysis are highlighted, including its use with atomic absorption, coherent forward scattering, laser excited atomic fluorescence, laser enhanced ionization and coupled methodologies. Prospects for future use and evaluation are given.     

Determination of phosphorus in steel with a stabilized-temperature graphite furnace and zeeman-corrected atomic absorption spectrometry

The determination of phosphorus in steel by graphite furnace a.a.s. is plagued by a spectral interference from the iron matrix which results in overcompensation when a continuum-source background corrector is used. Zeeman background correction using an alternating transverse magnetic field at the furnace eliminates this problem and allows a routine determination of phosphorus down to 0.002% in steel. Lanthanum is an effective matrix modifier for the phosphorus determination, but its enhancing effect depends largely upon the tube material used and the sample matrix. A 0.2% lanthanum solution was found to be optimum. The stabilized-temperature platform furnace concept allows an interference-free determination of phosphorus in steel, down to 0.002%, directly against aqueous standards. Atomizing the sample from a pyrolytic graphite platform in an uncoated graphite tube provides the optimum environment for a phosphorus determination.     

Determination of germanium by graphite-furnace atomic-absorption spectrometry

The premature loss of germanium as volatile GeO results in low sensitivity and poor reproducibility in the determination of germanium by graphite-furnace atomic-absorption spectrometry. This interference can be eliminated by suppressing the premature reduction of GeO(2) to GeO during the ashing step, and dissociating the germanium oxides into the atoms simultaneously with their vaporization during the atomization step. The premature reduction of GeO(2) to GeO has been successfully prevented by several approaches: (1) diminishing the reducing activity of the graphite furnace by (a) oxidizing the graphite surface and intercalating oxygen into the graphite lattice with oxidizing acids, such as nitric or perchloric, in the sample solution, or (b) using a tantalum-treated graphite furnace; (2) keeping the analyte as germanium (IV) by addition of sodium or potassium hydroxide to the sample solutions.     

The determination of manganese by electrothermal atomic absorption spectrometry with a graphite furnace at constant temperature

Many of the interferences reported earlier for the determination of manganese in a graphite furnace were not found when a modern graphite furnace was used. At high levels of chloride matrix, an interference which was observed in the modern furnace was reduced when manganese was determined under constant temperature conditions. In this work, the sample was introduced on a tungsten wire after the graphite furnace had reached a constant, preset temperature. Drying and ashing were accomplished outside the atomization furnace, reducing contamination from matrix materials.     

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.     

Solid sampling by electrothermal vaporization in combination with electrostatic particle deposition for electrothermal atomization multi-element analysis

A novel combination of electrothermal sample vaporization from one furnace and electrostatic deposition of the aerosol on a L'vov platform in a second graphite furnace used for subsequent electrothermal atomization multi-element analysis is described. The aerosol generated by vaporization of liquid as well as solid primary samples is transported to the graphite furnace by an Ar gas flow and is piped into the furnace through the dosing hole via a glass capillary mounted on the autosampler arm of a continuum source coherent forward scattering spectrometer. The deposition on the graphite platform is obtained electrostatically by a corona-like discharge. The near quantitative deposition of the produced and transported aerosol allows optimal direct determination of the transport efficiencies by comparing the signals obtained by measuring liquid samples directly with the spectrometer with signals obtained with samples transferred with electrothermal vaporization and electrostatic deposition. Over all transfer efficiencies up to 30% are observed with liquid primary samples. Results obtained with solid sampling of BCR CRM 189 Wholemeal flour are in good agreement with the certified values.     

Sensitive detection of ionic organolead compounds by coupling hydride generation (HG) with transversely heated graphite atomizer-atomic absorption spectrometry (THGA-AAS)

The detection of ionic alkyllead compounds using the coupling of flow injection analysis system-hydride generation (FIAS-HG) with transversely heated graphite atomizer atomic absorption spectrometry (THGA-AAS) has been worked out. Very low limits of detection can be achieved if the hydride products are enriched in the graphite furnace. Under optimised conditions (concentration of sodium borohydride, hydrogen peroxide and acidity as well as the furnace temperature) calibrations are carried out in the range of 0.1 to 5 μg/L. With a 1.5 mL sample loop, the limit of detection is calculated to be about 7 ng/L, but it can be lowered to below 1 ng/L if larger sample volumes are used for the enrichment.