Glass heavy element analysis

The potential of ultrasonic extraction for field-based extractions has been put into use in the industrial hygiene and environmental single-element analysis of, for example, lead from glass fibre filter ambient air samples [13,14] or from lead-based paint, urban dust and river sediment [15] hexavalent chromium from coal fly ash and paint chips [16] and strontium from river sediment [17]. Ultrasonic extraction has also proved effective as a prior step in multi-element determinations of heavy metals. 

Examples of applications of X-ray spectrometric analytical techniques to elemental determinations in a variety of materials are presented in Table 2.12. Some recent applications papers may be mentioned. Total reflection XRF has been applied by Xie et al. (1998) to the multielement analysis of Chinese tea (Camellia sinensis), and by Pet-tersson and Olsson (1998) to the trace element analysis of milligram amounts of plankton and periphyton. The review by Morita etal. (1998) on the determination of mercury species in environmental and biological samples includes XRF methods. Alvarez et al. (2000) determined heavy metals in rainwaters by APDC precipitation and energy dispersive X-ray fluorescence. Other papers report on the trace element content of colostrum milk in Brazil by XRF (da Costa etal. 2002) and on the micro-heterogeneity study of trace elements in uses, MPI-DING and NIST glass reference materials by means of synchrotron micro-XRF (Kempenaers etal. 2003). 

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,... 

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