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.     

Direct analysis of solid samples by atomic absorption spectrometry, following preconcentration of trace elements from seawater with 8-hydroxyquinoline

Summary 8-Hydroxyquinoline (8-HOQ) was used for the preconcentration of Cd, Cu, Mn, Pb and Zn from seawater prior to their determination by graphite furnace atomic absorption spectrometry using an inner miniature cup for solid sampling technique. The metal ions in seawater were precipitated quantitatively in the pH range 7–8.5 with 8-HOQ alone. The precipitate thus formed was directly analysed by an atomic absorption spectrometer equipped with a specially deviced graphite furnace and miniature cup. The present method was confirmed to be highly reliable for analysis of seawater. Detection limits (3_b) for Cd(II), Cu(II), Mn(II), Pb(II) and Zn(II) are 1.4, 10, 5, 10, and 6 ng l^–1, respectively, for the analysis of a 400-ml portion of seawater samples. Corresponding precision of 6–14% is typical for determination 5-fold above the detection limits.

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Direkte Analyse von Feststoffproben durch AAS nach Anreicherung von Spurenelementen aus Meerwasser mit 8-Hydroxychinolin

     

Direct determination of Cu,Mn, Pb,and Zn in beer by thermospray flame furnace atomic absorption spectrometry

In this work, thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) was employed for Cu, Mn, Pb, and Zn determination in beer without any sample digestion. The system was optimized and calibration was based on the analyte addition technique. A sample volume of 300 μl was introduced into the hot Ni tube at a flow-rate of 0.4 ml min⁻¹ using 0.14 mol l⁻¹ nitric acid solution or air as carrier. Different Brazilian beers were directly analyzed after ultrasonic degasification. Results were compared with those obtained by graphite furnace atomic absorption spectrometry (GFAAS). The detection limits obtained for Cu, Mn, Pb, and Zn in aqueous solution were 2.2, 18, 1.6, and 0.9 μg l⁻¹, respectively. The relative standard deviations varied from 2.7% to 7.3% (n=8) for solutions containing the analytes in the 25–50 μg l⁻¹ range. The concentration ranges obtained for analytes in beer samples were: Cu: 38.0–155 μg l⁻¹; Mn: 110–348 μg l⁻¹, Pb: 13.0–32.9 μg l⁻¹, and Zn: 52.7–226 μg l⁻¹. Results obtained by TS-FF-AAS and GFAAS were in agreement at a 95% confidence level. The proposed method is fast and simple, since sample digestion is not required and sensitivity can be improved without using expensive devices. The TS-FF-AAS presented suitable sensitivity for determination of Cu, Mn, Pb, and Zn in the quality control of a brewery.     

Determination of trace metals in sediment standard reference materials by graphite-furnace atomic absorption spectrometry with a stabilized temperature platform

Trace elements (As, Be, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, V, Zn) in NBS 1645 (river sediments), NBS 1646 (estuarine sediment), MESS-1 and BCSS-1 (marine sediments), IAEA SL-1 (Lake Sediment) and IAEA Soil-5, are determined by graphite furnace atomic absorption spectrometry with the L'vov platform. The samples (ca. 0.25 g) are dissolved in a mixture of nitric, perchloric and hydrofluoric acids in a PTFE bomb. Results based on direct calibration with simple aqueous solutions are in good agreement with those obtained by the method of standard additions and with recommended values. The relative standard deviations are generally 5–10%. Chromium determinations are also evaluated by inductively-coupled plasma/atomic emission spectrometry.     

Immobilization of 8-hydroxyquinoline onto silicone tubing for the determination of trace elements in seawater using flow injection ICP-MS

A rapid and simple on-line method is described for the preconcentration of Mn, Co, Ni, Cu, Zn, Cd and Pb from sea water using 8-hydroxyquinoline immobilized onto silicone tubing (Sil-8-HQ) via the Mannich reaction. Recoveries between 35 and 95% and limits of detection in the ppt range were obtained using a 2 m long Sil-8-HQ tube with a sample flow rate of 1.0 ml min(-1). A tube could be subjected to sample loading and elution cycles over 200 times. The capacity was 1.5 and 1.3 mug cm(-2) for Cu and Mn, respectively. Cu, Cd, Co, Pb, Mn, Zn and Ni were determined in coastal and open ocean seawater using flow injection inductively coupled plasma mass spectrometry (FI-ICP-MS). Good agreement with certified values for the certified reference materials NASS-4 and CASS-3 was demonstrated when quantitation was undertaken by the method of additions.     

高炉生铁化学分析用与光谱分析用国家标准样品的研制

在冶炼、铸造、加工等操作中采取多种工艺措施,研制了高炉生铁化学分析用与光谱分析用国家标准样品,对研制的标准样品进行严格的均匀性和稳定性检验.由国内8家具有资质的分析实验室参与协作定值.定值元素达19项(C,Si,Mn,P,S,Cr,Ni,Cu,Mo,V,Ti,Co,Als,Alt,As,Sb,Sn,Pb,Zn等).分析...     

Coupling of ultrasonic nebulization to flame furnace atomic absorption spectrometry—new possibilities for trace element determination

The use of ultrasonic nebulization (USN) with desolvation system for sample introduction in flame atomic absorption spectrometry (F AAS) and flame furnace atomic absorption spectrometry (FF AAS) with a nickel tube is described. Polytetrafluorethylene (PTFE) adaptors were built to replace the pneumatic nebulizer for USN-F AAS measurements. For USN-FF AAS analysis, an alumina injector allowed the direct introduction of the dry aerosol into the nickel tube. The analytical performance of both systems is shown for Ag, Bi, Cd, Cr, Cu, Mn, Pb, Sb, Se, Tl and Zn. The results demonstrate that a sensitivity gain of up to 39 times can be achieved using USN-FF AAS, mainly due to the increase in residence time and to the absence of dilution of the analyte by the flame gases, as the atomization takes place inside the nickel tube. However, elements that require higher atomization temperatures, such as Cr and Mn, are more efficiently determined using USN-F AAS. To evaluate the accuracy of the proposed methods for the determination of trace elements, five certified reference samples were analyzed, and good agreement was, in general, achieved between certified and determined values at a 95% confidence level. The relative standard deviation was frequently below 5%, demonstrating good precision, particularly for USN-FF AAS. In this sense, coupling of USN with F AAS and especially with FF AAS has proved to be simple, safe, with high precision and good accuracy, also maintaining some of the most important features of F AAS, such as the high analytical frequency and the low running cost.     

微波消解-GFAAS测定浅水湖泊底泥中重金属元素

探讨了采用微波消解作为底泥样品的前处理方法,运用石墨炉原子吸收法测定浅水湖泊底泥中Cu,Pb,Zn,Cd,Cr含量的实验条件.方法的RSD为2.0％～4.1％,平均回收率为97.4％～101.5％,Cu,Pb,Zn,Cd,Cr的检出限分别为0.4,5,2.8,0.25,2.5ng.该法适合于浅水湖泊底泥中重金属含量的测定.     

Transport efficiencies and analytical determinations with electrothermal vaporization employing electrostatic precipitation and electrothermal atomic spectroscopy

Analyte transport efficiencies of solid as well as liquid samples were determined for electrothermal vaporization (ETV). A graphite furnace of the boat-in-tube type was employed for ETV. The generated aerosol was transported by an argon flow via a tubing into an external precipitator and deposited on a L’vov platform with a corona-like discharge. The sample on the secondary platform was analysed with a laboratory-constructed coherent forward scattering multielement spectrometer. For determining the analyte transport efficiencies, the comparative measurements were carried out with standard solutions dosed directly on the platform in the spectrometer furnace. The simultaneously investigated elements were Cu, Fe and Mn in the standard reference material BCR CRM 189 wholemeal flour and in a multielement standard solution containing approximately the same element ratio as certified for the solid sample. ETV boat-to-L’vov platform transport efficiencies of approximately 19% for Cu, 24% for Fe and 19% for Mn were calculated for both solid samples and multielement standard solutions. Cu, Fe and Mn in wholemeal flour were determined simultaneously by calibrating against aqueous multielement standard solutions injected into the boat as well as by the standard addition method. The results agree satisfactorily, the deviations from the certified values are below 10% and the relative standard deviations are typically 5–8%. The limits of detection are 250 pg for Cu (λ=324.8 nm), 230 pg for Fe (λ=248.3 nm) and 90 pg for Mn (λ=279.8 nm), loaded into the ETV boat.     

原子吸收光谱法测定皇冠草地上部分的7种微量元素

采用原子吸收光谱法测定了皇冠草地上部分所含微量元素铜、锰、锌、铁、镉、铅、铬.结果表明,皇冠草地上部分含有较丰富的铜、锰、锌、铁,RSD≤4.23％(n=4),加标回收率99.20％～103.00％.     

Voltammetric procedure for trace metal analysis in polluted natural waters using homemade bare gold-disk microelectrodes

Voltammetric procedures for trace metals analysis in polluted natural waters using homemade bare gold-disk microelectrodes of 25- and 125-μm diameters have been determined. In filtered seawater samples, square wave anodic stripping voltammetry (SWASV) with a frequency of 25 Hz is applied for analysis, whereas in unfiltered contaminated river samples, differential pulse anodic stripping voltammetry (DPASV) gave more reliable results. The peak potentials of the determined trace metals are shifted to more positive values compared to mercury drop or mercury-coated electrodes, with Zn always displaying 2 peaks, and Pb and Cd inversing their positions. For a deposition step of 120 s at ?1.1 V, without stirring, the 25-μm gold-disk microelectrode has a linear response for Cd, Cu, Mn, Pb and Zn from 0.2 μg L^?1 (1 μg L^?1 for Mn) to 20 μg L^?1 (30 μg L^?1 for Zn, Pb and 80 μg L^?1 for Mn). Under the same analytical conditions, the 125-μm gold-disk microelectrode shows linear behaviour for Cd, Cu, Pb and Zn from 1 μg L^?1 (5 μg L^?1 for Cd) to 100 μg L^?1 (200 μg L^?1 for Pb). The sensitivity of the 25-μm electrode varied for different analytes from 0.23 (±0.5%, Mn) to 4.83 (±0.9%, Pb) nA L μmol^?1, and sensitivity of the 125-μm electrode varied from 1.48 (±0.7%, Zn) to 58.53 (±1.1%, Pb  nA L μmol^?1. These microelectrodes have been validated for natural sample analysis by use in an on-site system to monitor Cu, Pb and Zn labile concentrations in the Deûle River (France), polluted by industrial activities. First results obtained on sediment core issued from the same location have shown the ability of this type of microelectrode for in situ measurements of Pb and Mn concentrations in anoxic sediments.      

Preparation and homogeneity characterization of ten agricultural/food reference materials for elemental composition

Summary Ten agricultural/food reference materials (RM): bovine muscle powder, corn starch, hard red spring wheat flour, soft winter wheat flour, whole milk powder, wheat gluten, corn bran, Durum wheat flour, whole egg powder and microcystalline cellulose, were prepared by milling, irradiation, sieving, blending and packaging procedures. Homogeneity tests for 14 elements in randomly selected units were performed by the initiating laboratories by application of various analytical methods. Al, Ca, Cu, Fe, K, Mg, Mn, Na, Sr and Zn were determined by acid digestion flame atomic absorption spectrometry, and Cd, Co, Ni and Pb using acid digestion graphite furnace atomic absorption spectrometry after separation/preconcentration of the analytes by co-precipitation. In addition, the extensive set of analytical results obtained from the interlaboratory cooperative characterization campaign was assessed to provide homogeneity estimates for other elements. Measures of homogeneity were estimated from the within-laboratory precision from the more precise laboratories. All materials exhibited acceptable homogeneity for virtually all 29 elements (Al, As, B, Ba, Br, Ca, Cd, Cl, Co, Cr, Cu, Fe, Hg, I, K, Mg, Mn, Mo, N, Na, Ni, P, Pb, Rb, S, Se, Sr, V, Zn) for which best estimate concentration values were available, an essential pre-requisite in establishing reference values for these materials. Sixty-two percent of all homogeneity coefficients of variation (CV) were below 5%, with Br, Ca, Cl, Mg, Na, P, Zn and especially K and N exhibiting very high homogeneity CV less than 1% in some cases.Contribution no. 92–148 from Centre for Land and Biological Resources Research     

高压密封消解FAAS法分析5种冬青科苦丁茶嫩芽中无机元素及其分布

采集5种冬青科苦丁茶嫩芽样品,经高压密封消解,用火焰原子吸收光谱法测定Ca、Mg、Mn、Fe、Zn的含量。结果表明,在优化的测定条件下,Ca、Mg、Mn、Fe、Zn的回收率为90.1%~105.4%,测定结果的相对标准偏差为1.35%~3.78%(n=5)。用该方法对茶叶标准参考物(GBW 10016)进行了测定,测定结果与标准值相符合。5种冬青科苦丁茶嫩芽中所测元素的含量存在差异,但其总体分布具有一定的相似性,其中苦丁茶冬青嫩芽中Ca和Zn较高。     

Comparison Of Analytical Techniques For The Determination Of Trace Elements In Rain Water

Abstract

Summary-Two methods for the determination of cadmium, copper and lead in EPA reference precipitation sample, corresponding to 1987, 1988, 1989 and 1990 BAPMoN Intercomparison Program, have been compared: graphite furnace atomic absorption spectroscopy (GFAAS) and anodic stripping voltametry (ASV). A relatively good agreement was found between the two techniques and with the reference values. The results for the analysis of Cl and F by spectrophotometry, Ca, Mg, Na, K and Zn by AAS, and Fe, Mn, Cu, Ni, Pb and Cd by GFAAS in the same sample, corresponding to 1988 and 1989, showed good agreement with the stated values. The results of Easter Island rain waters for the years 1990 and 1991 are presented.     

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.     

Summary of preparation and homogeneity characterization of ten agricultural food reference materials for elemental composition

Summary Preparation and development has been completed of ten agricultural/food reference materials (RMs): bovine muscle powder, corn starch, hard red spring wheat flour, soft winter wheat flour, whole milk powder, wheat gluten, corn bran, durum wheat flour, whole egg powder and microcrystalline cellulose. Homogeneity tests for 14 elements, Al, Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sr and Zn were performed by the initiating laboratories by application of precise and reliable analytical methods based on flame atomic absorption spectrometry and graphite furnace atomic absorption spectrometry. An extensive set of analytical results obtained from the interlaboratory cooperative characterization campaign was assessed to provide homogeneity estimates for other elements. Estimates of homogeneity from within-laboratory precision indicated that all materials exhibited acceptable homogeneity for virtually all 29 elements (Al, As, B, Ba, Br, Ca, Cd, Cl, Co, Cr, Cu, Fe, Hg, I, K, Mg, Mn, Mo, N, Na, Ni, P, Pb, Rb, S, Se, Sr, V, Zn) for which best estimate concentration values are available. Two thirds of all homogeneity coefficients of variation were below 5%.     

Microanalytical determination of metallic constituents of river sediments

Summary The distribution of metallic constituents in torrential rivers as a function of the size particle cannot be frequently achieved by conventional analytical procedures, because of the lack of sufficient amounts of the fine fractions. For the study of river sediments in the Basque Country, microanalytical methods have been developed both for major (Na, K, Ca, Mg, Fe, Al, Si) and trace (Cu, Zn, Mn, Cr, Pb, Ni, Cd) components. Wet digestion in PTFE vessels at 140°C was done with 0.05 g sample using HNO₃-HClO₄-HF-H₃BO₃ or HNO₃-HClO₄, respectively. Further determinations were made by i) emission spectrometry (Na, K), ii) visible spectrophotometry (Al), iii) FIA (Fe, Si) and iv) AAS with flow spoiler (Ca, Mg, Cu, Zn, Mn) or graphite furnace (Cr, Pb, Ni, Cd). The proposed method has been checked with a standard sample obtaining mean values almost coincident with the certified ones and variation coefficients lower than 2% for major and 8% for trace components. Then it was applied to total samples and the fine fractions (<63 m) of 26 samples of sediments from three torrential rivers. Replicated values with analogous variation coefficients were obtained. Some considerations on distribution of major and trace constituents as a function of particle size are also included.     

Preparation and certification of tea leaves reference material

Summary Tea leaves reference material was prepared and certified for elemental composition. Japanese green tea leaves were ground, sieved to pass a 80-mesh screen, blended and bottled. The prepared material satisfied the homogeneity criteria for a reference material. Trace element analysis of the material was carried out by flame and graphite furnace atomic absorption and inductively coupled plasma atomic emission spectrometry.Certification of the material was performed using the data obtained by various analytical techniques and certified values are provided for Al, Ca, Cd, Cu, K, Mg, Mn, Na, Ni, Pb and Zn. The elemental composition of the tea leaves reference material is considered typical of Japanese green tea leaves.     

微波消解和电感耦合等离子体发射光谱法同时测定煤灰中的14种元素

应用微波消解和电感耦合等离子体发射光谱法同时测定煤灰中的常量、少量和微量元素Si、Al、Ca、Fe、Mg、Ti、K、Ba、Mn、V、Pb、Cr、Cu和Zn。考察了微波消解体系和消解条件，0．1g煤灰用10mL硝酸和1mL氢氟酸分解，加入10mL4％硼酸溶液分解氟化物沉淀。用本法测定煤飞灰标准参考物质的结果与标准值一致。方法准确，快速，回收率为94．2％～102．3％；RSD均小于5％。     

Determination of iron,cobalt, nickel,manganese, zinc,copper, cadmium and lead in human hair by inductively coupled plasma-atomic emission spectrometry

A method was standardized for the dissolution of hair samples and analysis was carried out by inductively coupled plasma atomic emission spectrometry (ICP-AES). Hair samples were brought into solution by using a mixture of nitric acid and hydrogen peroxide. Various parameters that influence the sample preparation, namely temperature, digestion time and ratio of acid mixture were studied and standardized. The optimized method has been employed to digest standard reference materials and hair samples of residents of India, collected from different age groups and sex, and analyzed for Fe, Co, Ni, Mn, Zn, Cu, Cd and Pb. The values agree for most of the metals with the data reported for human hair samples of residents of India. The NIES CRM Human Hair No. 5 and IAEA Reference Hair HH-1 certified reference materials were used in order to verify the accuracy of the method and the results were in excellent agreement with the certified values.