Chemical Modifiers in Modern Electrothermal Atomic Absorption Spectrometry

The role of chemical modifiers in modern electrothermal atomic absorption spectrometry is considered. It is demonstrated that the selection of the optimal chemical modifier largely determines the potential of the method for the analysis of complex samples. The mechanisms of the action of nitric and oxalic acids; magnesium, nickel, and ammonium nitrates; high-melting carbides; organic compounds, and some other; chemical modifiers are briefly discussed. The most promising fields of application of these modifiers are outlined.     

电热原子吸收光谱分析中的持久性化学改进剂

介绍了电热原子吸收光谱(ETAAS)分析中,克服基体效应的持久性化学改进剂研究概况。内容包括延长石墨平台使用寿命;降低空白信号值,改善检出限;分析信号持久稳定,改善精密度;导致ETAAS升温程序简化、快速;降低分析成本以及样品分析的应用情况等,引用文献36篇。     

Study of Some Tungsten-Containing Chemical Modifiers in Graphite-Furnace Atomic Absorption Spectrometry

Abstract

Several chemical modifiers based on tungsten have been evaluated: the individual modifiers W(VI) as WO₃ in aq. 0.2 M NH₃ and W(V) as W in H₂O₂ and the mixed modifiers W(VI)/NH₃ + Pd(II), W(V)/H₂O₂ + Pd(II), and W(V)/H₂O₂ + PO₄ ^3-. High efficiency of thermal stabilization for 18 analyte elements of high and moderate volatility has been demonstrated and possible mechanisms of stabilization are discussed.     

电热原子吸收分析中的固体进样技术

本文综述了电热原子吸收分析中固体进样技术的进展,详细讨论了固体直接进样和悬浮体进样和样品制备方法、进样工具、校正曲线、基体改进技术、分析性能及其最新应用。     

Determination of Tributyltin in Oysters by Electrothermal Atomic Absorption Spectrometry

Abstract

Graphite-furnace atomic absorption spectrometry for tributyltin in oysters is described. Tributyltin is extracted by n-hexane after digestion with hydrochloric acid. The 3[sgrave] detection limit for tributyltin is better than 0.01 mg Sn/kg. Typical absorbance values are about 0.10 for tributyltin contents as low as 0.03 mg Sn/kg. Tributyltin contents of 29 oyster samples are given.     

Study on the Atomization Process of Lithium in Electrothermal Atomic Absorption Spectrometry

A new method for determining the kinetic order and activation energy for atom formation in electrothermal atomic absorption spec-trometry is proposed. The assumption of first order kinetics for atom formation and the steady-state approximation which appeared in the previous models is avoided in the proposed method. The kinetic parameters for atom formation of Li have been obtained, and the effect of the amount of analysed sample, ashing temperature, atomization temperature, heating rate, gas flow and tube surface on the atomization of Li has also been investigated.     

Evaluation of Different Modifiers for the Determination of Arsenic in Leachate Samples from Sanitary Landfills by Electrothermal Atomic Absorption Spectrometry

The aim of the present work was to develop and validate a rapid and accurate method of arsenic determination in leachate samples by electrothermal atomic absorption spectrometry. Leachate samples from sanitary landfills are considered difficult samples to analyze due to severe matrix interferences. A comparative study of various chemical modifiers was performed: Pd, Mg, Au, Pt, Ru, Rh, Ir, C₆H₈O₇ (citric acid), Pd + Mg, Ir + Mg, and the permanent modifier Zr – Ir.

Among the modifiers tested, the mixture 5 µg Ir + 40 µg Mg provided the best performance, followed by the permanent modifier Zr – Ir (a coating of 200 µg Zr + 20 µg Ir). The permanent modifier was finally chosen due to the decreased background signal and sufficient sensitivity.

In order to investigate the presence of matrix interference and exploit the possibility of performing calibrations by simple aqueous solutions, calibration with aqueous standards, matrix matched standards and with standard additions was performed. It was observed that, in the presence of the Zr – Ir permanent modifier, the slopes of the calibration curve and the matrix-matched/standard addition curves were statistically different (checked by t-test). The recoveries from matrix-matched calibrations for three concentration levels were ranged between 96.4% and 100%. Precision experiments were also performed and the relative standard deviation (%RSD) for four different concentrations was ≤10%. The method was applied to the determination of arsenic in leachate samples collected in the solid waste sanitary landfill of Ano Liossia, Attika, Greece.     

Mahganese Determination In Blood Serum Using Electrothermal Atomic Absorption Spectrometry

Abstract

Twelve procedures of sample pretreatment for manganese determination in blood serum were tested in comparable instrumental conditions. the best results were obtained by dilution of serum with diluted nitric acid, which leads to formation of an internal matrix modifier composed of calcium and phosphoric acid. Other procedures may also give satisfactory results, but then as standards aqueous albumin solutions should be used.     

钨丝电热原子吸收光谱分析法测定痕量锌

蒸馏水中的锌与吡咯烷二硫代氨基甲酸铵(APDC)形成的络合物用CCl4萃取后,弃去有机相,水相用作配制锌标准溶液和制备样品溶液,从而解决了用钨丝电热原子吸收光谱法测锌时空白值太高而难以进行实际样品分析的问题.考察了影响萃取和钨丝电热原子吸收测定的各种实验条件.在进样10 μL样品溶液时,本方法的定量下限为5 μg/L.测定了3个国家标准物质(大米、人发和水系沉积物)中的锌含量,结果与推荐值一致.     

Determination of Lead, Chromium, Manganese and Zinc in Slurries of Botanical and Biological Samples by Electrothermal Atomic Absorption Spectrometry Using Tungsten-Containing Chemical Modifiers

Lead, Cr, Mn and Zn in slurries of botanic and biological samples were determined by electrothermal atomic absorption spectrometry (ETAAS) using W, Ir, NH₄H₂PO₄, W and NH₄H₂PO₄, Ir and NH₄H₂PO₄, W and Ir, and W + Ir + NH₄H₂PO₄ chemical modifiers in an 0.2% (v/v) Triton X-100 plus 0.2% (v/v) nitric acid mixture. Zeeman effect background correction was performed and platforms inserted into graphite tubes were used. Comprehensive comparative studies were carried out with respect to pyrolysis and atomization temperatures, atomization and background absorption profiles, characteristic masses, detection limits and accuracy of the determinations in the presence and absence of modifiers. The mixture of W + Ir + NH₄H₂PO₄ was found to be preferable for the determination of Pb, Cr, Mn and Zn in slurry samples. The pyrolysis temperatures of the analytes were increased up to 1250 °C for Pb, 1000 °C for Zn, 1400 °C for Cr and Mn by using W + Ir + NH₄H₂PO₄ with an 0.2% (v/v) Triton X-100 plus 0.2% (v/v) nitric acid mixture used as diluent solution. The optimum masses of the mixed modifier components were found to be 20 µg W + 4 µg Ir + 50 µg NH₄H₂PO₄. The characteristic masses of Pb, Cr, Mn and Zn obtained are 16.3, 5.6, 0.1 and 1.1 pg, respectively. The detection limits of Pb, Cr, Mn and Zn based on integrated absorbance for 0.5% (m v⁻¹) slurries were found to be 0.14, 0.06, 0.02 and 0.01 µg g⁻¹, respectively. The slurries of botanic and biological certified and standard reference materials were analyzed with and without the modifiers. Depending on the sample type, the percent recoveries increased from 63 up to 104% for analytes when using the proposed modifier mixture.     

Electrothermal Atomization Atomic Absorption Spectrometry with Platinum Tube Atomizer in Air

Abstract

An electrothermal atomization method of atomic absorption spectrometry using a platinum tube atomizer in air is described. The atomizer consists of 0.025 mm-walled platinum tube and two supports. The remarkable merit of the platinum atomizer is the stability in air, when heated. This paper describes the improved performance for volatile elements like alkalimetals. Detection limits and characteristic mass are calculated for 7 elements and compared with literature values. The platinum atomizer can be used with a simple, effective and relatively low-cost atomic absorption spectrometer for routine in situ analysis.     

An Inexpensive Probe for Sample Introduction in Electrothermal Atomization Atomic Absorption Spectrometry

Abstract

An inexpensive probe system for introduction of samples for analysis by electrothermal atomization atomic absorption spectrometry is described. The system involves mounting a capillary tube on a tripod stand to allow the probe to be inserted into the atomizer for analysis. Comparison between this method of atomization and conventional atomization off the atomizer wall for the measurement of cadmium is described.     

Iridium and Rhodium as Permanent Chemical Modifiers for the Determination of Ag, As, Bi, Cd, and Sb by Electrothermal Atomic Absorption Spectrometry

Performance of graphite platforms coated with Ir, Rh, and a mixture of both, as permanent modifiers for Ag, As, Bi, Cd, and Sb, was evaluated. The coating process is very simple: a solution containing Ir, Rh, or a mixture of both is pipetted on the platform inserted in a graphite tube, and this is submitted to a temperature program. High pyrolysis temperatures are allowed, especially for As and Bi, 1400°C, in the Ir + Rh-coated platform. The sensitivity remains about the same for all analytes with different coatings, except for As in the Ir-coated platform, for which a remarkable gain was obtained in comparison to the other coatings. The lifetimes of the treated tubes were in the range 50 to more than 1000 cycles, being especially long for Sb and Ag in the Rh-coated platform, more than 600 and 1000 cycles, respectively. The Rh coating could not be used for Bi and Cd. Analysis of a certified reference water and of acid oyster tissue digests showed the absence of interference and good precision. Advantages of the permanent coatings are the possibility of low blanks byin situcleaning of the modifier and shorter analysis time.     

浊点萃取-电热原子吸收光谱法分析铬的形态

提出了测定铬形态的新方法——浊点萃取-电热原子吸收光谱法(PPE-ETAAS)。该法基于利用非离子表面活性剂Triton X-100的浊点现象，当加热至其浊点时，溶液分为两相，Cr(Ⅲ）与8-羟基喹啉形成的疏水性螯合物进入富胶束相中，从而实现与Cr(Ⅵ）的分离。在本法中，8-羟基喹啉既作为化学分离，富集剂，又作为ETAAS测定中的化学改进剂。对影响浊点萃取分离的主要因素进行了详细的研究。在最优实验条件下，方法测定Cr(Ⅲ）的检出限为0．023μg/L；相对标准偏差为1．1％(C=2．0μg/L，n=6)。本法具有简便、灵敏、富集倍数高和避免使用有机溶剂的优点。     

Determination of Thallium In Solid Environmental Samples By Electrothermal Atomic Absorption Spectrometry

Abstract

A method for the determination of thallium in solid environmental samples is developed. After destruction of the sample, TI(III) is extracted from 0.5 M hydrobromic acid solution into diisopropyl-ether. the organic phase is evaporated and the residue taken up in a mixture of sulfuric and nitric acids. Measurements are carried out with an atomic absorption spectrometer with Zeeman background corrector. the accuracy of the method is tested by analysis of certified reference materials and the method is applied to fly ash and emitted particulate matter from a municipal refuse incinerator and to soil samples.     

Direct Determination of Some Trace Elements in Milk by Electrothermal Atomic Absorption Spectrometry

Abstract

A method for the determination of trace and ultra-trace elements (Fe, Cu, Mn, Co, Cr, Mo and Ni) in milk by electrothermal atomic absorption spectrometry is described. Milk samples are injected directly into the graphite tube. Optimal operating conditions have been established. The method appears to be accurate and reproducible. The relative standard deviation was, on average, 9%.     

Determination of Arsenic by Electrothermal Atomic Absorption Spectrometry Using Arsine Preconcentration on Palladium-Containing Adsorbents

A procedure was developed for the preconcentration of arsine on palladium-containing adsorbents followed by the determination of arsenic by electrothermal atomic absorption spectrometry. Aqueous suspensions of the adsorbent were placed in a graphite furnace at the determination step. The selection of the adsorbent was substantiated; adsorption properties of palladium-containing adsorbents were studied to validate their modifying properties. The absolute and concentration limits of detection for arsenic were 28 pg and 12 ng/L, respectively (sample volume of 100 mL).     

Direct Analysis of Coffee and Tea for Aluminium Determinationby Electrothermal Atomic Absorption Spectrometry

 A method for direct analysis of tea and coffee samples by using electrothermal atomic absorption spectrometry is described. Coffee and tea from different sources were analyzed without digestion step. For slurry analyses the samples were ground, sieved at 105 μm and then suspended in 0.2% v/v HNO₃ and 10% v/v Triton X-100 medium. For liquid phase aluminium determination the samples were prepared in the same way and only the liquid is introduced directly into the graphite furnace. Calibration was performed by aqueous standards for both cases and the determinations were carried out in the linear range between 50 and 250 μg L⁻¹. The characteristic mass of aluminium and the detection limit were 45 pg and 2 μg L⁻¹, respectively. Using a typical 0.1% m/v coffee slurry sample, the relative standard deviation of measurements (n=15) for repeatability was about 8.2%. Received December 27, 1998. Revision March 18, 1999.