Portable x-ray fluorescence spectrometry for measuring multiple airborne metals: a NIOSH screening method under development
Lawryk, N. and Chen, B.
2002
American Industrial Hygiene Conference, AIHce PDCs - San Diego, June 1 - 2, paper 84
Lawryk, N. and Chen, B., (2002), "Portable x-ray fluorescence spectrometry for measuring multiple airborne metals: a NIOSH screening method under development", American Industrial Hygiene Conference, AIHce PDCs - San Diego, June 1 - 2, paper 84.
| Abstract: |
| In welding and other metalworking operations, illnesses can result from excessive inhalation exposures to metals such as chromium, nickel, and zinc. Portable XRF can help determine airborne metal concentrations within minutes of sample collection, thereby facilitating exposure assessment and control strategies. A set of 128 experimentally generated welding fume samples were collected on 37 mm diameter filters of four different media (cellulose ester, polypropylene, Teflon, and PVC). All filters were analysed by portable XRF for iron, chromium, nickel, zinc, copper, and manganese. Four welding procedures were sampled: gas metal arc welding and flux core arc welding on mild and stainless steel substrates. Fume deposit masses ranged from less than 0.5 to 60 milligrams, equivalent to a range from less than 0.3 to greater than 10 times the occupational exposure limit (OEL) for most metals of concern. XRF calibration was verified using Mylar backed thin film standards. Elemental concentrations were directly proportional to total fume mass (correlation coefficient > 0.98) for total fume deposits less than 30 milligrams. To simulate workplace dust in the samples, Arizona road dust (1-80 micrometer particle diameter) deposited on the filters at a mass equivalent of 0.5 times the OEL did not change the spectra reported by the instrument when compared to samples without dust deposits that were collected under identical conditions. Teflon filter media had the lowest metal contamination and therefore lower limits of detection and quantitation than cellulose ester. Further testing of the XRF on location at workplaces is planned. Field portable XRF spectrometry continues to show promise as a fast, reliable, and comparatively inexpensive screening technology for assessing airborne metal exposures. |
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