Non-dispersive systems in atomic fluorescence spectroscopy—III : Scattering by particles and its correction in practical analysis

In the determination of trace metals in sample solutions containing high concentrations of matrix material, the usefulness of the atomic fluorescence technique may be limited by the scatter signal from particulate matter in the flame. The nature and extent of this phenomenon are investigated and various methods of correction for it are discussed. These methods are applied in several practical analyses of high-purity metals, plant materials and soil samples.     

Analysis of heavy metals in atmospheric particulate by ion chromatography

Cu, Ni, Zn, Co, Fe+2, Mn, Cd, Fe+3 and Pb are easily separated and detected in isocratic mode by ion chromatography with post-column derivatization using a bifunctional ion-exchange column and an eluent formed by oxalic acid (28 mM) and sodium nitrate (250 mM). The separation is optimised by using a suggested sample solution containing a given concentration of chloride. Detection limits were 10-15 ppb for all the metals except for cadmium and lead, for which detection limits of 30 and 60 ppb were found, respectively. The method was tested on an atmospheric particulate certified sample. The measured values were in good agreement with certified values. Real samples of atmospheric particulate from industrial and urban sites were analysed and the results are discussed.     

Analysis of leachable and total trace metals in air particulate matters by capillary electrophoresis

A new analytical procedure was developed for simultaneous determination of ammonium, leachable and total metals in fine and coarse air particulate matters using a new capillary electrophoresis (CE) procedure, with a new buffer system containing 10 mM histidine, 2 mM 18-crown-6 and 8 mM lactic acids with pH adjusted to 4.0. A two complexes system, 18-crown-6 ether and lactic acid, was developed to solve the co-migration problem of NH(4)(+) and K(+) and to give satisfactory separation of transition metals. Satisfactory separation and quantitation of NH(4)(+), K(+), Ca(2+), Na(+) , Mg(2+) and Zn(2+) were obtained using the CE procedure developed for both leachable and total metals in coarse (10-3 mum) and fine (<3 mum) air particulate matters. Wide working ranges (ppb to ppm range) and sensitive detection limits (ppb) were obtained for the cations investigated. The reliability was established by parallel method comparison with the ICP-AES method. The analytical procedure developed is shown to provide a quick, sensitive, precise and economic method for simultaneous determination of ammonium, leachable and total metals in air particulate matters.     

Semi-Automated Determination of Heavy Metals in Autopsy Tissue Using Robot-Assisted Sample Preparation and ICP-MS

The endoprosthetic care of hip and knee joints introduces multiple materials into the human body. Metal containing implant surfaces release degradation products such as particulate wear and corrosion debris, metal-protein complexes, free metallic ions, inorganic metal salts or oxides. Depending on the material composition of the prostheses, a systemic exposure occurs and may result in increasing metal concentrations in body fluids and tissues especially in the case of malfunctions of the arthroplasty components. High concentrations of Cr, Co, Ni, Ti and Al affect multiple organs such as thyroid, heart, lung and cranial nerves and may lead to metallosis, intoxications, poly-neuropathy, retinopathy, cardiomyopathy and the formation of localized pseudo tumors. The determination of the concentration of metals in body fluids and tissues can be used for predicting failure of hip or knee replacements to prevent subsequent severe intoxications. A semi-automated robot-assisted measurement system is presented for the determination of heavy metals in human tissue samples using inductively coupled plasma mass spectrometry (ICP-MS). The manual and automated measurement processes were similarly validated using certified reference material and the results are compared and discussed. The automation system was successfully applied in the determination of heavy metals in human tissue; the first results are presented.     

Emission spectrographic determination of trace elements in atmospheric particulate matter

Air containing particulate material was passed continuously for one month through a low-volume air sampler equipped with a cyclone to exclude particulates greater than 10 μm in diameter. The samples and filters were ashed in a low-temperature plasma and, after addition of In₂O₃ support, palladium internal standard and graphite buffer, the ashes were analyzed by a.c. are emission spectrometry. Standard samples were prepared from a commercial standard containing 49 elements. The procedure allows the determination of 14 trace metals (Ag, Al, Cr, Cu, Fe, Ga, Mn, Mo, Ni, Pb, Sn, Ti, V, Zn) with relative standard deviations of 1.4–15.1%. The procedure has been applied successfully to monthly determinations of the average atmospheric concentrations of these elements in Kobe City for the past three years.     

Analysis of voltammetric data for the evaluation of seasonal changes of the Ni, Cd, Pb and Cu content in atmospheric particulate PM2.5

In this paper, the preliminary results of a study on concentration of heavy metals in PM2.5 (atmospheric particles with aerodynamic diameter less than 2.5 microm) fractions of atmospheric particulate matter, sampled in Milan, are presented. This work aims to develop an electroanalytical method to analyse Pb, Cu, Cd and Ni in PM2.5 and to investigate seasonal and weekly trends in the amount of PM2.5 and its composition for considered metals. The samples have been selected within the seasons ranging from September 2002 to November 2003 so that they represent the possible seasonal changes; the samples within this period have been chosen in order to have data relevant to both working days and holidays. The determination of Cd, Pb and Cu has been carried out by Differential Pulse Anodic Stripping Voltammetry, whereas the concentration of Ni has been determined by Differential Pulse Adsorptive Cathodic Stripping Voltammetry. The concentrations of the metals in the sampled atmosphere and in the PM2.5 have been evaluated; through ANOVA possible seasonal or weekly variations in the above cited concentrations have been investigated.     

Referee analysis of precious metal sweeps and related materials

Sweeps samples are often complex mixtures containing from trace amounts to 20% of one or more precious metals distributed in matrices consisting of widely varying mixtures of base metals or their oxides. Three collection procedures are described that are suitable for the isolation of precious metals from base substances. One is based on direct fusion of the sample (high-grade sweeps) with sodium peroxide, and the others on collection of the precious metals by fire-assay techniques using either nickel sulphide or silver. The precious metals are then determined either gravimetrically or by atomic-absorption or plasma-emission spectrometry.     

Online monitoring of aerosols with an energy-dispersive X-ray spectrometer

A continuously working sampling and analyzing device was developed and tested. It is suitable for monitoring of metals bound to particulate matter in emissions of stack gases. The samples were precipitated on a pure quartz fiber filter tape and analyzed shortly afterwards non-destructively by an energy dispersive X-ray spectrometer (EDXRS). By using this method a wide range of elements with atomic numbers from 19 (K) to 82 (Pb) can be analyzed. New experiments have shown that the novel combined particle sampling and analysis system (X-DUST) could also successfully be used for the monitoring of toxic elements in ambient air.     

Online monitoring of aerosols with an energy-dispersive X-ray spectrometer

A continuously working sampling and analyzing device was developed and tested. It is suitable for monitoring of metals bound to particulate matter in emissions of stack gases. The samples were precipitated on a pure quartz fiber filter tape and analyzed shortly afterwards non-destructively by an energy dispersive X-ray spectrometer (EDXRS). By using this method a wide range of elements with atomic numbers from 19 (K) ¶to 82 (Pb) can be analyzed. New experiments have shown that the novel combined particle sampling and analysis system ¶(X-DUST) could also successfully be used for the monitoring of toxic elements in ambient air.     

Performance of radar absorbing materials by waveguide measurements for X- and Ku-band frequencies

In this work, samples consisting of an elastomeric matrix containing different kinds of active materials in particulate form were prepared for reflectivity measurements. The materials individually used in weight contents of 80% in polychloroprene matrix were: carbonyl-iron (CI) and doped ferrite powders. The microwave reflectivity levels were determined from the magnetic and dielectric properties of the elastomeric composites obtained from scattering data, by fitting the samples in a waveguide, for measurements in the frequency range from 8 to 16 GHz. Better microwave absorption for X-band was obtained for CI while doped ferrite absorbed at higher frequencies (Ku-band).     

Bioaccessibility of selected trace metals in urban PM<Subscript>2.5</Subscript> and PM<Subscript>10</Subscript> samples: a model study

Bioaccessibility of trace metals originating from urban particulate matter was assessed in a worst case scenario to evaluate the uptake and thus the hazardous potential of these metals via gastric juice. Sampling was performed over a period of about two months at the Getreidemarkt in downtown Vienna. Concentrations of the assayed trace metals (Ti, Cr, Mn, Co, Ni, Cu, Zn, Mo, Ag, Cd, Sn, Sb, Tl and Pb) were determined in PM_2.5 and PM₁₀ samples by ICP-MS. The metal concentrations in sampled air were in the low picogram to high nanogram per cubic metre range. The concentrations in PM_2.5 samples were generally lower than those in PM₁₀ samples. The average daily intake of these metals by inhalation for a healthy adult was estimated to be in the range of <1 ng (Tl) to >1,000 ng (Zn). To estimate the accessibility of the inhaled and subsequently ingested metals (i.e. after lung clearance had taken place) in the size range from 2.5- to 10-μm aerodynamic equivalent diameter, a batch-extraction with synthetic gastric juice was performed. The data were used to calculate the bioaccessibility of the investigated trace metals. Extractable fractions ranged from 2.10% (Ti in PM_2.5) to 91.0% (Cd in PM_2.5), thus yielding bioaccessible fractions (PM_2.5–10) from 0.16 ng (Ag) to 178 ng (Cu).     

Determination of heavy metals by isotachophoresis

The suitability of isotachophoresis for the analysis of metals in, e.g., environmental samples was studied. In a cationic operational system the heavy metals Fe, Cu, Ni, Cd, Co, Zn, Pb and Mn were simultaneously determined. The separation was achieved through complex formation with one of the counter ions, hydroxyisobutyric acid. The other counter ion was acetic acid, the leading ion was 0.02 M potassium or sodium (pH 4.1) and the terminator was H+. The analysis time was 15 min at 60 microA in a 0.2 mm I.D. capillary. Aqueous samples containing ppm and ppb amounts were enriched on a cation exchanger with an extremely low affinity for sodium (Chelex 100). Good recovery, linearity, precision and accuracy were obtained even down to the ppb range. Although the sensitivity of the method is not greater than that of some of the more established methods for the individual metals, a great advantage of isotachophoresis is the simultaneous determination of the metals, with equal response factors. An example is given of the determination of metals, including aluminium, in serum.     

Determination of trace cadmium in environmental water samples using ion-interaction reversed-phase liquid chromatography with fluorescence detection

An ion-interaction reversed-phase liquid chromatographic method has been developed for the determination of cadmium at low microg/l concentrations in environmental water samples. Cadmium and other matrix metals were separated through on-column complexation with 8-hydroxyquinoline sulphonate, using an octadecylsilica column and a mobile phase containing 15% acetonitrile, 10-13 mM tetrabutylammonium hydroxide, 5 mM 8-hydroxyquinoline 5-sulphonic acid and 10 mM acetic acid-acetate buffer (pH 4.8-5.4). Under the above conditions Cd(II) could be easily resolved from excess concentrations of matrix metals and could be detected at concentrations as low as 2 microg/l using fluorescence detection at 500 nm (based upon a 100-microl injection). The method showed a slightly curved detector response over the range of interest [up to 1 mg/l Cd(II)] and was successfully applied to the determination of trace Cd(II) in water samples containing large excesses of Mg(II) and Zn(II) and other matrix metals.     

Condensation of analyte vapor species in graphite furnace atomic absorption spectrometry

A shadow spectral digital imaging technique (SSDI) with charge coupled device (CCD) camera detection was used to investigate the spatial and temporal distribution of condensation clouds of analyte species generated in a graphite furnace during the atomization of 5–40-μg masses of metals. Complex, non-uniform structures of aerosol species located away from both the graphite tube axis and walls are prevalent. Species giving rise to observed signals are likely clusters of metals in the case of Ag, Au and Pd, and oxide aerosols for elements such as Al, Ca and Mg. Source scatter often arises during the atomization of relatively large masses of analytes (or during the atomization of real samples containing high concentrations of concomitant matrix species) in the graphite furnace due to such aerosol formation. The SSDI technique is an extremely useful aid to the elucidation of this phenomenon and imaging at several wavelengths using both line and continuum sources in combination with (thermal, incandescent) emission from these structures permits a more complete picture to be developed.     

Analysis of water-soluble fraction of metals in atmospheric aerosols using aerosol counterflow two-jets unit and chemiluminescent detection

A new analytical system for a semi-continuous analysis of water-soluble fraction of particulate metals is described. The system combines the continuous sampling of atmospheric aerosols into deionized water using the Aerosol Counterflow Two-Jets Unit and on-line chemiluminescent detection of water soluble fraction of metals in collected aerosols. The potential of analytical system was studied using Fe³⁺, Cu²⁺ and Co²⁺ as model metals in atmospheric aerosols. The detection limits of particulate Fe³⁺, Cu²⁺ and Co²⁺ (S/N?=?3) are 24, 41 and 0.4?ng?m^?3, respectively. The presented set-up allows the determination of concentration of water-soluble fraction of particulate metals in ‘real time’ with time resolution of 30?min. The system is sufficiently robust for the field application. The method has been applied to the measurement of selected metals in urban TSP (Total Suspended Particles) aerosols in Brno in the Czech Republic. The concentrations of particulate water-soluble Fe³⁺, Cu²⁺ and Co²⁺ were found in the range of 35 to 290, 42 to 462 and 0.5 to 9?ng?m^?3, respectively.     

Chemical fractionation of elements in airborne particulate matter: primary results on PM10 and PM2.5 samples in the Lazio region (central Italy)

This paper describes how a two-step chemical fractionation method that allows the determination of 17 elements in airborne particulate matter, has been applied to a monitoring campaign of PM10 and PM2.5 in the Lazio region (Italy). This method involved an extraction in a pH buffered aqueous solution followed by a microwave-assisted acid digestion of the residue. With respect to the determination of the total elemental contents, the evaluation of a soluble fraction provides more reliable information on the presence and of the destiny of heavy metals in the environment. Furthermore, the pH buffered extraction conditions chosen, rendered the results independent of the intrinsic acidity of the collected samples and, although the chemical fractionation has a purely operational function, it facilitates the study of the relationship between the distribution of solubility and the different emission sources. Results are discussed in relation to the different concentration and the different degrees of solubility of the elements observed in two sampling sites; one in an urban and one in a rural environment. Since in-parallel sampling of PM2.5 and PM10 were performed in both sites, the influence of particle size is also discussed. Behaviour of some tracers deriving from both vehicular traffic, with particular attention to re-suspended road dusts, and naturally generated particulate matter, such as marine aerosol and Saharian dust, are discussed.     

Surface analysis of particulates from laboratory hood exhaust manifold

Particulate samples collected from a laboratory ventilation manifold during routine maintenance were analyzed to determine if particulate composition had changed as a result of changes in the laboratory's atmosphere. This ventilation manifold exhausts more than 100 fume hoods. The particulate samples were analyzed using static secondary ion mass spectrometry (SIMS). The negative SIMS spectra showed abundant Cl^?, NO₃^?, and HSO₄^?, consistent with the use of mineral acids in the laboratory. Cluster anions containing primarily Zn (but also other transition metals) were detected, which signaled corrosion of the manifold's galvanized steel by the volatilized acids. The most abundant ions in the cation SIMS spectra were derived from cyclohexylamine (CHA), which had been used as an antiscaling agent in the facility's boiler. Steam from the boiler, which contained CHA, was used to humidify the building air; this practice stopped in 1997. The abundances of the CHA‐derived ions were significantly lower in the samples collected in 2004 and 2006 than in the 1992 samples, indicating that the CHA is being slowly depleted. Changes in the relative abundances suggest exponential depletion from the manifold with rate constants that are on the order of 0.01 to 0.04 month^?1. Published in 2007 John Wiley & Sons, Ltd.     

Performance evaluation of two chelating ion-exchange sorbents for the fractionation of labile and inert metal species from aquatic media

The performance of two iminodiacetate chelating resins, applied in an element fractionation scheme, was investigated for the characterization of marine and stream water samples collected in potentially contaminated harbor and industrial zones. The comparison involved an evaluation of the sorption/desorption behavior of Cd, Cu, Pb and Zn on Chelex-100, a sorbent extensively employed for metal speciation studies, and on Lewatit TP-207, a material with similar chelating characteristics for which no applications for fractionation studies are reported. A characterization of the latter resin in terms of the influence of sample pH on the uptake of metals from aqueous solutions and their subsequent acid elution was carried out. Fractionation studies were performed on natural water samples and model solutions resembling their composition, spiked with micromolar concentrations of the metals. The operationally defined fractionation scheme is based on dynamic adsorption of the resin-labile fractions of metals on microcolumns made of the sorbents. This stage is followed by a batch procedure in which the eluent from the column is contacted with fresh resin to discriminate between the relatively stable species unable to react with the resin during the column interaction time, and the strongly complexed metals that do not interact with the sorbent even for periods of several hours. Results were obtained from coarsely filtered sub-samples and from specimens passed through membrane filters of pore size 0.45 and 0.22 µm. The method was also assessed with model solutions of the metals containing variable concentrations (in the 10^-3–10^-7 molar range) of complex forming agents such as nitrilotriacetic acid and trans-1,2-diaminocyclohexane-N,N,N,N-tetraacetic acid. An additional batch method, in which a fixed amount of resin was contacted with sample solution for increasing periods of time and the amount of metal remaining in solution measured as a function of the elapsed time, was used to obtain information on the kinetics of dissociation of species formed in the presence of added complexants. The behavior of both resins was similar, demonstrating that the discrimination of species derived from experiments with Chelex-100 may be properly validated by independent fractionation tests carried out with Lewatit TP-207. The behavior of the sorbents is also discussed in terms of the possible influence of particulate or colloidal materials and of kinetic effects related to the presence of complexing agents.     

Trace Metal Speciation and Research in Marine Geochemistry

Abstract

In order to precise the origin and behaviour of trace metals associated with coastal marine sediments, marine geochemists frequently utilize various methods of sequential extraction. The main objective is to test the potential mobility / stability of particulate metals in the natural environments. Several examples are presented in the article, namely: i/ Exchangeable Pb from podzolic soils of the drainage basin of a lagoon which sediments and phreatic waters are for a large part inherited from the surrounding soils; ii/ Evolution of particulate metals in an estuary; iii/ Mobility of metals at the sea bottom interface; iv/ Role of amorphous components of estuarine sediments and suspended matter; v/ Effects of dredging activities on solubility of metals in an estuary; vi/ Behaviour of heavy metals in lagoons.

Main results obtained from the extraction procedures are described, as well as particular difficulties encountered when applying some classical methods.