Multi-elemental analyses

Multi-element analyses involving solvent extraction and high performance liquid chromatography (HPLC) have also been described. The extracts, containing metal-chelate complexes with sulphur-containing reagents, such as dithizone and diethyldithiocarbamate, were used directly for determination of the metals by HPLC.14... 

PXRFs provide rapid, low cost, nondestructive, quantitative and/or qualitative multi-element analyses of many different sample media that require little or no sample preparation and instrument calibration for many applications. The two example presented here illustrate the use of PXRF in mapping rock units and mineralized zones, and this can empower the user to make on-the-fly decisions to optimize sampling strategy in order to... 

In a search for sources of alkaline materials in rural air and rain, we have sampled and performed multi-element analyses on ambient particulate matter and potential source materials. Ambient aerosols were sampled daily using single Nuclepore filters or Florida State University "streakers." Samples of soil and unpaved road materials were also collected and analyzed. The samples were analyzed by various multi-element methods, including ion-and proton-induced X-ray emission and X-ray fluorescence, as well as by atomic absorption spectrophotometry. Visual observations, as well as airborne elemental concentration distributions with wind direction and elemental abundances in aerosols and source materials, suggested that soil and road dust both contribute to airborne Ca. Factor analysis was able to identify only a "crustal" source, but a simple mass balance suggested that roads are the major source of Ca in rural central Illinois in summer. 

This short chapter finishes with multi-collector devices for true simultaneous multi-element analyses. 

Present atomic emission spectrophotometers allow multi-element analyses to be performed either simultaneously or sequentially. This ability is the result of progress made in optics, excitation sources, detectors and microcomputers. Atomic emission, which was initially used in the metallurgical industry, has now expanded into many areas and competes with atomic absorption. 

F. Laborda, M. J. Baxter, H. M. Crew, J. Dennis, Reduction of polyatomic interferences in inductively coupled plasma mass spectrometry by selection of instrumental parameters and using an argon-nitrogen plasma effect on multi-element analyses, J. Anal. Atom. Spectrom., 9 (1994), 727-736. 

Element- and group-specific separations have been achieved for multi-element analyses with chelating materials (, ) Using this approach chemical separations can be tailored for certain... 

Because such chemical studies of pots are so numerous, there now exist quite large databases of ceramic analyses against which new multi-element analyses can be compared, providing that the chosen elements and the precision and accuracy of their measurements are comparable. Some analysts, particularly those at the Missouri University Research Reactor (MURR), have decomposed some of these databases into regional groups known as compositional paste reference units (CPU) against which new data can be compared. 

Sodium silicate is somev at more difficult to analyze than many other materials because of the formation of the relatively long lived radionuclide Na whose emissions interfere with the detection of other elements. Nevertheless we were able to determine, in a sample of sodium silicate, that many heavy elements of toxicological concern were undetectable down to the ppm to ppb level in the undiluted silicate (13), An XRF spectrometer can be configured to perform sequential multi-elemental analyses. It is less sensitive to the elements of lower atomic number. Also, since the X-rays penetrate only to a depth of about 10 urn, the sample must be homogeneous. Solid samples must be presented to the X-ray beam with a flat surface. However, the relative ease of sample preparation and the ability to run glasses and solutions with only minor dilution make X-ray fluorescence a useful technique where analysis for a wide range of impurities is required,... 

Frequently, samples collected during environmental studies are small and contain low concentrations of metals. Preparation of such samples for residue analysis should include few sample transfers and reagents and should result in the smallest possible volume in order to minimize metal dilution and contamination. Many methods in the literature do not accommodate both small sample volumes and low metal concentrations. Therefore, it has become increasingly important to develop methods to analyze environmental samples at relevant concentrations 81). Graphite furnace atomic absorption (GFAA) can provide the requisite detection limits, but multi-element analyses are quite time... 

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