Sequential Multi-element Analysis Research Articles

Simultaneous Or Sequential Multi-Element Graphite Furnace Atomic Absorption Spectrometry Techniques: Advances Within The Last 20 Years

Electrothermal or graphite furnace atomic absorption spectrometry (ETAAS or GFAAS) is one of the most widely used techniques for determining elements in different matrices (e.g., foodstuffs, pharmaceuticals, biological specimens, nanomaterials, polymers, fuels and environmental media). Numerous elements can be simply and quickly determined with high precision and accuracy, low detection limits, and at moderate cost. The technique is also suitable for direct solid and slurry sample analysis. A crucial feature of this technique is that it can perform simultaneous or sequential multi-element analysis. Over the years, many instruments have come on the market for multi-elemental analysis using mostly line source (LS) GFAAS and high-resolution continuum source (HR-CS) GFAAS. This review covers publications from 2000 to 2020related to the simultaneous or sequential multi-elemental analysis by LS-GFAAS and HR-CS-GFAAS. Mainly the applications, the limits of detection, the use of internal standardization and other aspects regarding the matrix, pyrolysis and atomization temperatures and modifiers are discussed. Finally, a critical comparison is made between the LS-GFAAS and HR-CS-GFAAS techniques.

Analysis of Nanomaterials Based on Indium and Zinc Oxides by High Resolution Atomic Absorption Spectrometry with the Use of Continuous Spectral Source and Electrothermal Atomization

The properties of nanostructured materials based on zinc and indium oxides can be modified by adding alloying elements to obtain the necessary electrical or optical properties. For example, the specificity of the chemical properties of ZnO and In2O3 for the determination of toxic gases is achieved by immobilizing Au, Ag, etc., nanoparticles on their surface. Control of the material composition plays an important role in determining the dependence between the dopant content and functional properties of the materials. The study is aimed at the development of a methodical approach to the multielement determination of catalytic dopants (Ag, Au) and matrix elements in nanostructured tin and indium oxides using the method of high resolution atomic absorption spectrometry with electrothermal atomization (ETAAS) and continuous spectral source. The matrix of the synthesized nanostructured materials is the corresponding oxide with possible oxygen deficiency due to the temperature conditions of the synthesis (300–700°C), and the content of additives (Ag, Au) is varied from 1 to 3 wt %. Optimal conditions of pyrolysis and atomization for sequential multielement analysis by the ETAAS method are determined. The optimal pyrolysis temperatures for determining Ag and Au (for both oxides), In, and Zn are 1000, 1600, 1200, and 900°C, respectively. The optimal atomization temperatures for determining Ag and Au (for nanomaterial based on indium oxide), Au (for nanomaterial based on zinc oxide), In, and Zn are 1800, 2200, 2100, 2200, and 1500°C, respectively. The accuracy of analyte determination reaches 1–4% (rel.). The correctness of the results is confirmed by inductively coupled plasma mass spectrometry. The developed method provides control of the composition of synthesized nanostructured materials for their more efficient use in photovoltaics, as well as in production of chemical sensors for detection of harmful compounds like CO, NO2, and NH3.

2. Simultaneous and/or rapid sequential multi-element analysis of soils by X-ray fluorescence spectrometry

2. Simultaneous and/or rapid sequential multi-element analysis of soils by X-ray fluorescence spectrometry

Laser-excited atomic fluorescence spectrometry in a graphite furnace with an optical parametric oscillator laser for sequential multi-element determination of cadmium, cobalt, lead, manganese and thallium in Buffalo river sediment

It is demonstrated, for the first time, that solid-state lasers based on optical parametric oscillation (OPO) allow relatively rapid sequential multi-element analysis of samples by laser-excited atomic fluorescence spectrometry (LEAFS) in a graphite furnace. These lasers are tunable by facile computer keyboard control over the wavelength region 220–2000 nm. A method is described for the sequential multi-element determination of cadmium, cobalt, lead, manganese and thallium in a river sediment standard reference material (NIST SRM 2704) by graphite furnace LEAFS. With a slew rate of 0.125 nm s–1, the OPO laser could be tuned to cover the wavelength range needed for these elements, from 228 to 304 nm, in 15 min. This allowed each element to be determined sequentially with the analysis time determined primarily by the slow heating cycle of the furnace rather than the laser wavelength tuning. Detection limits in the multi-element mode were 545, 111, 28, 445 and 24 fg for cadmium, cobalt, lead, manganese and thallium, respectively, limited primarily by the low repetition rate of the laser (10 Hz). The multi-element detection limits were within a factor of 2–4 of those in the single element mode. Higher excitation energies, by a factor of 2–5, were required to optically saturate the transitions of the analytes in the sediment sample solution compared with aqueous standards. By use of several aliquots of one sample solution, and simple aqueous calibration, it was possible to analyze the sample, accurately, for the five elements over a concentration range between 1 ng ml–1 for thallium and 460 ng ml–1for manganese. Different dilutions were not necessary owing to the long calibration range of the technique. The high sensitivity of LEAFS allowed sufficient initial dilution to remove an interference on thallium that is normally irresolvable by atomic absorption measurements of the same sample in the same graphite furnace.

Sequential Multielement Analysis of Cd, Cr, Ni, and Pb in Human Tissues by Inductively Coupled Plasma Spectrometry

The role of trace metals in cancer has been the subject of conjecture, and reports of different authors are often conflicting and contradictory. Attention is focused primarily on (a) four metals (As, Cd, Cr, and Ni) that have been implicated as human carcinogens on the basis of epidemiological investigations, and (b) compounds of nine metals (Be, Cd, Co, Cr, Fe, Ni, Pb, Ti, and Zn) that have been reported to induce cancers in experimental animals. Most toxic elements affect multiple organ systems, with specific biochemical processes and (or) organelles as targets. Their toxic effect usually involves an interaction between the free metal ion and the specific target protein. Cells or organs involved in the transport of trace metals, i.e., muscle, liver, renal tubular, or gastrointestinal cells, are particularly susceptible to toxicity. Most of these elements are concentrated intracellulary; heavy metals deposit in tissue after exposure. There are three principal binding sites for metals on the nucleic acid molecules: the phosphate groups, the heterocyclic bases and the 2-OH groups in the case of RNA (Eichhorn et al 1979). It is generally accepted that a combination of environmental factors and life-style contribute to about 70-90% of cancer cases. The most important factorsmore » are smoking (about 30-40%) and food (30-50%), whereas environmental pollution contributes only a small percentage (1-3%). Augustin and Zejda found that geochemical factors in the environment such as radioactive elements and heavy metals were possible causes of the high incidence of cancers in some districts in Czechoslovakia. In view of conflicting reports in the literature, the concentrations of Cd, Cr, Ni and Pb were determined in the kidney and brain of Saudi patients with malignant or benign tumors. 20 refs., 8 tabs.« less

A computer controlled flame-CFS spectrometer with photon counting detection and multipass mirror configuration

An automated flame coherent forward-scattering (CFS) spectrometer with a xenon high-pressure lamp has been constructed for fast sequential multielement analysis. To improve detection limits an on-axis multipass mirror system is used and, in addition, the light intensity is detected by the photon counting technique. The spectrometer is operated by a menu oriented program. Computer controlled functions, interfacing, data acquisition, and handling as well as analytical modes are described. Nonlinear analytical curves are used for evaluation and for calculating the detection limits and the analytical working range. The detection limits of the analytical system are compared with those of other CFS, AAS, and AES spectrometers. Even with a continuum light source, which allows fast sequential multielement capability, the detection limits are lower than those reported for flame CFS before. Analytical results obtained for drinking water samples are compared to measurements with flame AAS.

Sequential multielement analysis of a single aerosol filter by different instrumental and wet-chemical methods

The direct instrumental methods X-ray fluorescence spectrometry (XRFS) and instrumental neutron activation analysis (INAA), and, after digestion of the sample, inductively coupled plasma mass spectrometry (ICP-MS) were applied in sequence to analyse small single aerosol filters. XRFS detected up to 19, INAA up to 22, and ICP-MS up to 33 elements. In total, up to 45 elements were determined, and, for a number of additional elements limits of detection could be given. For many elements, the data quality could be checked by cross-comparison of the results of two or all three methods. These methods very meaningfully complement each other and, in the manner used, allow the determination of all elements of interest in a small aerosol filter sample.

Use of an on-axis multipass system to improve the detection limits of coherent forward scattering spectroscopy and flame atomization

Sequential and simultaneous multielement analysis has been carried out using spectrometry of coherent optical forward scattering (CFS) in combination with a continuum light source and flame atomization. An improvement of the detection limits of CFS devices for simultaneous and sequential multielement analysis could be achieved using a multipass mirror configuration. Two on-axis spherical mirrors effect a multiple reflection of incident light through the flame. Thus the CFS intensity is increased by an extended effective path length. The improvement factors for the detection limits have been found in the range between 2.8 and 6.7 depending on the element to be determined. The experimental results for single element as well as simultaneous multielement analysis obtained with and without the multipass mirror system, are related to the estimated improvement factors.

Automated trace metal analyses of slurried solid samples by graphite furnace atomic absorption spectrometry with application to sediments and suspended matter collected in natural waters

The work described deals with the analysis of sediment and suspended particulate matter samples slurried in a glycerol medium. Automated sequential multi-element analysis was possible using the same modifier (i.e., palladium mixed with the main matrix elements) for all of the six analytes studied (Cu, Cd, Pb, Co, Cr and Ni). The reliability of the method was confirmed by analyses performed on standard reference soils and sediments supplied by NIST and IAEA. Representative sampling of the slurry is also discussed.

Sequential multi-element analysis of sediments and soils by inductively-coupled plasma/atomic emission spectrometry with a computer-controlled rapid-scanning echelle monochromator

A computer-controlled rapid-scanning echelle monochromator is used to determine the major, minor and trace elements in reference sediments and soils. The high resolving power of the echelle spectrometer effectively decreases line overlap interferences, and permits a wide selection of analytical lines to be used. The concentrations of 17 elements in five standard materials are determined by using a single set of analytical lines without any corrections for line overlap interferences. Averages of relative standard deviations and relative deviations from the certified values for the 17 elements range from 2.4 to 4.3% and from 1 to 5%, respectively.

A new look at sodium diethyldithiocarbamate in potentiotitrimetry

Potentiotitrimetric methods for the determination of some cations with sodium diethyldithiocarbamate (NaDDC) have been critically examined. Although single cations such as Cu 2+, Cd 2+, Pb 2+, Ni 2+, Ag +, Zn 2+, and In 3+ can be satisfactorily determined, we conclude that sequential multielement analysis of more than 2 elements does not yield accurate results. We have not been able to determine ZrO 2+. We report new quantitative data for Hg 2+, Sb 3+, Bi 3+, Se 4+, and Te 4+ vs NaDDC. Pd 2+, Fe 2+, and Fe 3+ can be determined only under rigidly controlled pH/buffer conditions and are thus not considered analytically useful.

A Computerized Research Microdensitometer for Spectrographic Data Analysis

A research grade microdensitometer has been modified and updated with a linear optical encoder to monitor and control accurately photographic plate position and digitized read out of density data. This measurement system is fully interfaced to a Data General time-shared computer network. Plate position is controlled to within ±0.0001 in. (0.0025 mm) via a closed-loop computer, stepper motor, and incremental linear optical encoder system. Plate movement and density sampling are under computer control with resulting data stored on disc memory for later analysis. Program techniques, including error analysis, have been developed to determine unknown wavelengths to within ±0.006 Å from spectral dispersion data fit to third-order polynomials. Analytical implications, especially relating to sequential multi-element analysis, are discussed. The completed instrument may be applied to a variety of spectroscopic and nonspectroscopic problems.

Inductively coupled plasma-BASIC programmable computer controlled double monochromator for sequential multielement analysis

Inductively coupled plasma-BASIC programmable computer controlled double monochromator for sequential multielement analysis

Sequential multi-element analysis using silver and copper ion-selective electrodes

A simple method is described for the rapid and accurate sequential determination of as little as 50 µg ml–1 of Ag+, Cu2+, Ni2+, Cd2+, Pb2+, Zn2+, Fe3+, Th4+ and V4+ ions in binary, tertiary and quaternary mixtures. The method involves direct titration with sodium diethyldithiocarbamate at pH 4–6 in 50%V/V ethanol using silver and copper ion-selective electrodes. Potentiometric curves with sharp consecutive inflection breaks at the equivalence points and a mean recovery of 99.6%(mean standard deviation 0.3%) are obtained. The method has been used satisfactorily for the determination of the major alloying elements in brass, motor-brass, silver-brazing and nickel-silver alloys by both direct and spiking titration techniques. The results agreed well with the certified values.

Sequential multi-element analysis of small fragments of glass by atomic-emission spectrometry using an inductively coupled radiofrequency argon plasma source

A method is described for the quantitative multi-element analysis of small fragments (200–500 µg) of glass using an inductively coupled radiofrequency argon plasma source. The glass samples are digested with a mixture of hydrofluoric and hydrochloric acids and chromium is added as an internal standard. An ultrasonic nebuliser is used in order to reduce to a minimum the volume of solution required for each analysis. A single monochromator and detection system is employed, and the wavelength regions of interest are examined sequentially by means of a specially constructed control unit. The results for aluminium, barium, iron, magnesium and manganese show that the analysis of glass fragments in the range 200–500 µg can be achieved with coefficients of variation of approximately 10%. Standard glasses were analysed to assess the accuracy of the method.