A Hydride Generation-Ultrasonic Nebulization System for Plasma Spectrometries

Both hydride generation (HG) techniques and ultrasonic nebulizers (USN) have been extensively applied for the determination of trace elements by inductively coupled plasma (ICP) atomic emission spectrometry or by ICP mass spectrometry. HG is actually a preconcentration system, which has good power of detection and high sensitivity for As,Se, Sb, Bi, Te,Hg, Pb, and Sn.     

Flame-in-gas-shield miniature flame hydride atomizers for ultra trace element determination by chemical vapor generation atomic fluorescence spectrometry

Flame-in-gas shield miniature hydride atomizers (FIGS) have been investigated and evaluated in view of their alternative use to miniature diffusion flame hydride atomizer (MDF) to determination of hydride forming elements by atomic fluorescence spectrometry (AFS). Chemical vapour generation (CVG) by aqueous phase derivatization by NaBH₄ in a continuous flow generator (CF) was employed for the generation of volatile hydrides of As, Sb, Bi, Se, Te and Sn. A dispersive AFS apparatus using electrodeless discharge lamps (EDL) as the excitation sources has been employed for both spectra acquisition and analytical determinations. The characteristics of FIGS in terms of background emission spectra, most intense AF spectral lines and limits of detection were compared with those of most popular MDF. FIGS presents a lower background emission with respect to MDF, allowing also the control of the molecular fluorescence of OH radicals in the determination of bismuth. Limits of detection for FIGS compare very well with to those obtained by MDF giving improvement factor of 5.5, 4.4, 3.6, 3.6, 0.7 an 0.5 for Bi, As, Se, Son, Te and Sb. Accuracy of FIGS has proven by determination of arsenic and antimony in seawater (NASS-5) and river water (SRLS-4) certified reference materials and bismuth in unalloyed copper (CuV 398, CuVI 399) standard reference materials by dispersive CVG-AFS.     

UV photochemical vapor generation-atomic fluorescence spectrometric determination of conventional hydride generation elements

A systematic investigation of UV photochemical vapor generation (photo-CVG) and its potential application for seven typical hydride-forming elements (As, Sb, Bi, Te, Sn, Pb and Cd) when combined with atomic fluorescence spectrometry (AFS) detection is presented. These analyte ions were converted to volatile species following UV irradiation of their aqueous solution to which low molecular weight organic acids (such as formic, acetic or propionic acid) had been added, and introduced to an atomic fluorescence spectrometer for subsequent analytical measurements. The experimental conditions for photo-CVG and the interferences arising from concomitant elements were carefully investigated. Limits of detection as low as 0.08, 0.1, 0.2 and 0.5 ng mL^− 1 were obtained for Te, Bi, Sb and As, respectively, comparable to those by hydride generation-AFS. The RSDs obtained with the proposed method for these elements were better than 5% at 50 ng mL^− 1. It is noteworthy that the presence of TiO₂ nanoparticles combined with UV irradiation remarkably enhances the CVG efficiencies of Se(VI) and Te(VI), which cannot form hydrides with KBH₄/NaBH₄. Moreover, photo-CVG has a greater tolerance toward interferences arising from transition elements than hydride generation, and this facilitates its application to the analysis of complicated sample matrices.     

Application of hydride generation to atomic-absorption spectrometric analysis of wines and beverages: a review

The use of hydride-generation systems for atomic-absorption spectrometry and other spectrometric methods for the determination and control of As, Sb, Bi, Pb, Sn, Se and Te in wines and beverages is reviewed.     

Evaluation of tungsten coil electrothermal vaporization-Ar/H2 flame atomic fluorescence spectrometry for determination of eight traditional hydride-forming elements and cadmium without chemical vapor generation

A tungsten coil electrothermal vaporizer (W-coil ETV) was coupled to an Ar/H(2) flame atomic fluorescence spectrometer for the determination of eight traditional hydride-forming elements (i.e., As, Bi, Ge, Pb, Sb, Se, Sn, and Te) as well as cadmium without chemical vapor generation. A small sample volume, typically 20muL, was manually pipetted onto the W-coil and followed by a fixed electric heating program. During the vaporization step, analyte was vaporized off the coil surface and swept into the quartz tube atomizer of AFS for further atomization and excitation of atomic fluorescence by a flow of Ar/H(2) gas, which was ignited to produce the Ar/H(2) flame. The tungsten coil electrothermal vaporizer and Ar/H(2) flame formed a tandem atomizer to produce reliable atomic fluorescence signals. Under the optimal instrumental conditions, limits of detection (LODs) were found to be better than those by flame atomic absorption spectrometry (FAAS) or inductively coupled plasma optical emission spectrometry (ICP-OES) for all the nine elements investigated. The absolute LODs are better or equivalent to those by hydride generation atomic fluorescence spectrometry (HG-AFS). Possible scattering interferences were studied and preliminary application of the proposed method was also reported.     

Interferences of hydride forming elements and of mercury in the determination of antimony, arsenic, selenium and tin by hydride-generation AAS

Summary By means of the radiotracer technique supplemented by conventional absorption measurements, the interferences of As, Bi, Hg, Pb, Sb, Se, Sn and Te in amounts between 10 g and 1 mg with the determination of As, Sb, Se and Sn by hydride generation AAS using heated quartz tube were investigated during the hydride-generation and the atomization stages. Amounts up to 100 g of Hg and Pb do not cause any detectable interference. The interference of Bi and Te is dominant in the hydride-generation stage and that of As, Se, Sb and Sn in the atomization stage. Tin is retained to a considerable extent in the quartz tube and the resulting memory effect makes the determination of As, Sb, and Se impossible. In the absence of interfering elements, the efficiency of the formation of hydrides of As, Sb, Se and Sn was close to 100%. However, a reduction of Sb(V) to Sb(III) prior to the hydride-generation is necessary for which an improved procedure was developed.

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Störungen von Hydridbildnern und von Quecksilber bei der Bestimmung von Antimon, Arsen, Selen und Zinn durch die Hydrid-AAS

Zusammenfassung Mittels der Radiotracertechnik und Atomabsorptionsspektrometrie wurde der Störeinfluß unterschiedlicher Mengen (10–1000 g) von As, Bi, Hg, Pb, Sb, Se, Sn und Te auf die Bestimmung von As, Sb, Se und Sn mit der Hydrid-AAS untersucht. Durch diese Verfahrenskombination war es möglich, das Ausmaß der Störungen durch diese Elemente sowohl im Hydrierungs- als auch im Atomisierungsschritt zu bestimmen sowie zum großen Teil auch die Gründe für ihr Auftreten aufzuklären. Keine nachweisbare Störung verursachen Hg und Pb bis zu jeweils 100 g. Die Störung durch Bi und Te tritt hauptsächlich im Hydrierungsgefäß auf, hingegen die durch As, Sb, Se und Sn im wesentlichen in der Quarzabsorptionszelle. Bei Zinn wurde ein starker Memoryeffekt festgestellt, der aus der Ablagerung dieses Elements in der Quarzküvette resultiert und der die Bestimmung von As, Sb und Se völlig unmöglich macht. Ohne diese Störelemente liegen die Hydrierungsausbeuten für As, Sb, Se und Sn bei nahezu 100%. Bei Antimon ist allerdings eine vorherige Reduktion von Sb(V) zu Sb(III) notwendig, für die ein verbessertes Verfahren vorgeschlagen wurde. Denn durch die Radiotracertechnik konnte nachgewiesen werden, daß die während der Alterung von Sb(V)-Lösungen durch Kondensationsprozesse entstehenden Polysäuren nicht mehr hydriert werden können.

     

Photo-induced chemical-vapor generation for sample introduction in atomic spectrometry

Chemical-vapor generation (CVG) is widely used as a sample-introduction technique for atomic spectrometry, with the advantages of efficient matrix separation, high analyte-transport efficiency, and high selectivity and sensitivity. Recently, photo-induced CVG (photo-CVG) was demonstrated to be a powerful alternative to conventional CVG. In photo-CVG, volatile species (including hydrides, elemental, carbonylated and alkylated analytes) are generated from non-volatile precursors by ultraviolet irradiation in the presence of low-molecular-weight organic compounds. Photo-CVG is simple, fast and environmentally friendly with little interference from transition metals. Its analytical applications have been demonstrated in analysis of Hg, conventional hydride-forming elements (As, Bi, Sb, Se, Te), transition metals (Ni, Co, Fe) and non-metals (I). In addition, photo-CVG was developed as a simple, effective interface between high-performance liquid chromatography (HPLC) and atomic spectrometry. This review summarizes the applications of photo-CVG for various analytes and as a novel interface between HPLC and atomic spectrometry. We also discuss current research on the possible reaction mechanism of photo-CVG.     

Determination of Antimony in Brass by On-line Hydride Generation Atomic Fluorescence Spectrometry Alkaline Solution

The hydride generation(HG) technique combined with atomic spectrometry as a detection system has become one of the most powerful analytical tools for the determination of elements, such as As, Sb, Bi, Se, Te,Ge, Sn and Pb. Normally, the hydride is generated by the reaction between an acidic sample solution with tetrahydroborate. However, when some inorganic ions such as the transition metal ions are present in the reaction matrix, interference arise. Some approaches for minimizing the interference have been suggested, including the addition of various reagents such as thiourea and iron(III) solution. Interfering metals can also be removed by precipitation. The procedure involved filtration before the solution was acidified. In order to reduce the steps of the process, hydride generation from alkaline solution was described for the determination of selenium in copper and nickel materials.     

Behaviour of the dithiocarbamate complexes of arsenic, antimony, bismuth, mercury, lead, tin and selenium in methanol with a hydride generator

A study was carried out with a continuous hydride generator coupled to an atomic emission spectrometer with inductively-coupled plasma to determine whether hydrides of As, Bi, Pb, Sb, Sn and Se and mercury vapor could be generated in methanol solutions of their dithiocarbamate complexes. It was found that (with the exception of Pb) hydride generation with sufficient efficiency for simultaneous multi-element determination is achieved using 0.25% NaBH(4)-0.6 mol 1(-1) HCl as reaction medium. The detection limit was found to be 0.2 ng ml(-1) for As, 30 ng ml(-1) for Bi, 0.03 ng ml(-1) for Se, Sb and Sn.     

Study on the hydride generation atomic absorption spectrometry of As, Sb, Bi, Se, Sn, Te and Hg in the presence of cadmium and zinc salts

Summary HG-AAS of As, Sb, Bi, Se, Sn, Te and Hg in the presence of Cd or Zn salts has been studied. It has been found that there is an interference effect on the AAS signal in the presence of these salts. In each case the interference by Cd salts is stronger than that by Zn salts. The decrease of the Te signal in the presence of Cd salts is considerable.     

Mechanism of volatile hydride formation and their atomization in hydride generation atomic absorption spectrometry.

The mechanism of volatile hydride generation (HG) and the formation of analyte atoms in the quartz cell atomizer used in the determination of hydride-forming elements (As, Bi, Ge, Pb, Sb, Sn, Te etc.) by atomic absorption spectrometry (AAS), have been critically reviewed. The nascent hydrogen mechanism failed to explain hydride generation under different experimental conditions when tetrahydroborate (THB), amineboreanes (AB) and cyanotrihydroborate (CBH) were used as reductants. Various experimental evidence suggested a non-nascent hydrogen mechanism, in which the transfer of hydrogen directly bonded to boron to an analyte takes place. In electrochemical hydride generation (EcHG), the reduction of the analyte species and subsequent hydrogenation was proposed. The mechanism of analyte atom formation in a quartz tube atomizer has been explained by the following hypotheses: thermal decomposition, oxidation by 02 and collisions by hydrogen free radicals. The free-radical mechanism satisfactorily explains most of the analytical implications. The significant variation in the experimental conditions required to generate different analyte hydrides makes it difficult to arrive at a generalized mechanism of hydride formation.     

Comparison of tungsten coil electrothermal vaporization and thermospray sample introduction methods for flame furnace atomic absorption spectrometry

Flame furnace atomic absorption spectrometry (FF-AAS) is a newly developed flame atomic absorption spectrometric technique based on arranging a flame furnace onto the top of the flame burner head. In this fundamental investigation, 25 elements were carefully tested by using either thermospray FF-AAS or tungsten coil electrothermal vaporization FF-AAS, of which 15 volatile and semi-volatile elements (Cd, Tl, Ag, Pb, Zn, Hg, Cu, Sb, Bi, Te, In, As, Se, Sn and Au) exhibited better limits of detection compared to those by conventional FAAS; however, non-volatile or refractory elements (Fe, Co, Ni, Cr, Mn, Pd, Pt, Al, Be and V) showed inferior sensitivities by the proposed methods.     

Multiple microflame quartz tube atomizer: Study and minimization of interferences in quartz tube atomizers in hydride generation atomic absorption spectrometry

A systematic study was performed to evaluate the performance of a multiple microflame (MM) quartz tube atomizer (QTA) for minimizing interferences and to improve the extent of the calibration range using a batch system for hydride generation atomic absorption spectrometry (HG AAS). A comparison of the results with conventional QTA on the determination of antimony, arsenic, bismuth and selenium was performed. The interference of As, Bi, Se, Pb, Sn and Sb was investigated using QTA and MMQTA atomizers. Better performance was found for MMQTA, and no loss of linearity was observed up to 160 ng for Se and Sb and 80 ng for As, corresponding to an enhancement of two times for both analytes when compared to QTA (analyte mass refers to a volume of 200 μl). For Bi, the linear range was the same for QTA and MMQTA (140 ng). With the exception of Bi, the tolerance limits for hydride-forming elements were improved more than 50% in comparison to the conventional QTA system, especially for the interferences of As, Sb and Se. However, for Sn as an interferent, no difference was observed in the determination of Se and Sb using the MMQTA system. The use of MMQTA-HG AAS complied with the relatively high sensitivity of conventional QTA and also provided better performance for interferences and the linear range of calibration.     

Estimation of Uncertainty Budgets in Analysis of Nickel by ICP-MS and High-Resolution Mass Spectrometry with a Glow Discharge

Moscow University Chemistry Bulletin - This paper estimates uncertainty budgets in determining the content of impurities of 15 elements (P, Mn, Fe, Cu, Zn, As, Se, Ag, Cd, Sn, Sb, Te, Tl, Pb, Bi)...     

The Study of Determining As,Sb, Bi in Geological Samples With ICP-AES

The three elements,As,Sb,Bi, the same as Ag,Au,Cu, Hg, Mo, Pb, Sn, W,Zn,are important indicated elements in looking for gold mine, which are usually determined by atomic fluorescent spectrometer (AFS). Since the conditions of their hydride generation are different and the contents among them have no proportion relation, they can't be determined simultaneously. And because the dynamic range of AFS is narrow,the samples must be diluted or weighed again if the content of a certain element is too high or low.     

Some observations on the chemiluminescence of atoms in acetylene flames supported by air and argon-oxygen mixtures

A study has been made of the chemiluminescent emission of As, Bi, Cd, Ge, Hg, I, Mo, Pb, Sb, Se, Sn, Te, V and Zn in the primary combustion zones of air-acetylene and argon-oxygen-acetylene flames, supported at an open burner port during the aspiration of aqueous solutions of their salts. In general, elements having excitation, potentials greater than 4 eV show considerably greater atomic chemiluminescence in the primary zone than “thermal” atomic emission in the interconal region. Various mechanisms are suggested for the energy-transfer reactions between metal atoms and excited flame species, particularly carbon monoxide.     

Systematic investigations of the multi-element preconcentration from copper by precipitation of the matrix as copper(I) oxide and copper(I) thiocyanate

Two methods for multi-element preconcentration from copper by reductive matrix precipitation are presented. In systematic investigations on the coprecipitation behaviour of Ag, Al, Au, Bi, Cd, Co, Cr, Fe, Ga, In, Mn, Mo, NJ, Pb, Sb, Se, Sn, Te and Zn during precipitation of the copper matrix as Cu₂O or CuSCN, the separation parameters were optimized. By combination with a hexamethyleneammonium hexamethylenedithiocarbamate collector precipitation, a concentration of 8 elements (Cu₂O precipitation) or 13 elements (CuSCN precipitation) in a small volume was achieved. The limits of detection of the procedures are, depending on the element, 0.1–5 μg g^?1 for flame atomic absorption spectrometry (AAS) and 0.01–0.1 μg g^?1 for graphite furnace AAS. The relative standard deviations are about 3%. The analytical performance of the procedures is compared with that of an electrolytic copper separation.     

Certified sediment reference materials for trace element analysis from the National Metrology Institute of Japan (NMIJ)

Two types of sediment reference material (NMIJ 7302-a and 7303-a) for trace elements analysis have been prepared and certified by the National Metrology Institute of Japan in the National Institute of Advanced Industrial Science and Technology (NMIJ/AIST). The original materials were collected from a bay near industrial activity in Kyushu (NMIJ CRM 7302-a; marine sediment) and from Lake Biwa (NMIJ CRM 7303-a; lake sediment). The sediment materials were air-dried, sieved, homogenized, packaged in 1000 glass bottles (60 g each), and radiation sterilized. Certification of these CRM for trace elements was conducted by NMIJ, where each element was determined by at least two independent analytical techniques. Isotope-dilution inductively coupled plasma mass spectrometry (ICP–MS) was applied for certification of all the elements except mono-nuclide elements such as As and Co. Other techniques such as ICP–MS with quadrupole mass spectrometry and sector-field mass spectrometry, inductively coupled plasma atomic emission spectrometry (ICP–AES), and atomic absorption spectrometry (AAS), were also used. Certified values have been provided for 14 elements (Sb, As, Cd, Cr, Co, Cu, Pb, Hg, Mo, Ni, Se, Ag, Sn, and Zn) in both CRM.     

Improving the analytical performance of hydride generation non-dispersive atomic fluorescence spectrometry. Combined effect of additives and optical filters

The effects of tetrahydroborate and acid concentration and the presence of l-cysteine and thiourea were investigated in the determination of As, Bi and Sn using continuous flow hydride generation atomic fluorescence spectrometry (HG AFS). The aim was to find conditions allowing the control of those effects exerting negative influence on the analytical performance of the HG AFS apparatus. The effects taken into account were: (i) the radiation scattering generated by carryover of solution from the gas–liquid separator to the atomizer; (ii) the introduction of molecular species generated by tetrahydroborate decomposition into the atomizer; and (iii) interference effects arising from other elements in the sample matrix and from different acids. The effects (i) and (ii) could be controlled using mild reaction conditions in the HG stage. The effect of HG conditions on carryover was studied by radiation scattering experiments without hydride atomization. Compromised HG conditions were found by studying the effects of tetrahydroborate (0.1–20 g l⁻¹) and acid (0.01–7 mol l⁻¹) concentration, and the addition of l-cysteine (10 g l⁻¹) and thiourea (0.1 mol l⁻¹) on the HG AFS signals. The effect of optical filters was investigated with the aim of improving the signal-to-noise ratio. Optical filters with peak wavelengths of 190 and 220 nm provided an improvement of detection limits by factors of approximately 4 and 2 for As and Te, respectively. Under optimized conditions the detection limits were 6, 5, 3, 2, 2 and 9 ng l⁻¹ for As, Sb, Bi, Sn, Se and Te, respectively. Good tolerance to various acid compositions and sample matrices was obtained by using l-cysteine or thiourea as masking agents. Determination of arsenic in sediment and copper certified reference materials, and of bismuth in steel, sediment, soil and ore certified reference material is reported.     

Hydride generation – in-atomizer collection of Pb in a quartz trap-and-atomizer device for atomic absorption spectrometry – an interference study

Interferences of selected hydride forming elements (As, Sb, Bi, Se and Sn) on lead determination by hydride generation atomic absorption spectrometry were extensively studied in both on-line atomization and preconcentration (collection) modes. The commonly used on-line atomization mode was found free of significant interferences, whereas strong interference from Bi was observed when employing the preconcentration mode with plumbane collection in a quartz trap-and-atomizer device. Interference of Bi seems to take place in the preconcentration step. Interference of Bi in the collection mode cannot be reduced by increased hydrogen radical amount in the trap and/or the atomizer.