Presentation on theme: "XRF X-ray Fluorescence Spectrometry Tom Murphy Qualitative Screening or Quantitative Analysis."— Presentation transcript:
XRF X-ray Fluorescence Spectrometry Tom Murphy Qualitative Screening or Quantitative Analysis
Major Users of XRF Geoprospecting Alloy identification for safety and recycling Remediation of lead in paint, metals in soil Waste processing such as oil industry Forensics for legal analysis Consumer product analysis Art and Archeology Industrial hygiene
More powerful units have radioactive source, better detection levels, fewer interferences, but are not usually portable, and if portable require licensing
Hand-held XRF – Thermo Fisher Loan -analysis in ~1 minute -no extraction or other preparation of sample -detects ppm concentrations of many metals -non destructive -no cross contamination or fouling of sensor
Sample Preparation/Calibration The sample matrix can be important The best cases really suitable for XRF analysis is the ‘atomic mixing level’ that is found in: -All liquids (homogenous, one physical phase!) -Glass -Large crystals (used for “finger printing” gem origins) -Most alloys
Mixing varies from impossible to easy -results vary from qualitative to quantitative Oil in mineral precipitant “impossible” to mix Toxic skin cream can mix but will separate, “Cao Cap” This fish needs a better grinder but can shoot replicates
Interferences A few elements interfere, arsenic and lead can effect each other, especially in low energy XRFs -in samples with high lead, low arsenic results will be unreliable The Matrix can be an issue. If there is more than 10% water in a sample, it can either enhance or reduce the signal. Drying of the sample is required.
Geoprospecting – Pathfinder analysis -can’t see low concentrations of gold with XRF but can find co-occurring elements like platinum
Jewelry -XRF quickly detects Pb, Hg, Cd etc. -no sample preparation Found clasps with >40% Pb -ingestion has killed child in USA -chronic toxicity more common
Lead Amulets/Curse Tablets - oral very dangerous, dermal less dangerous but not well documented, no sample preparation needed for XRF - Khmer Beads 45% lead Thai Charm Roman Curse Tablet
Other Consumer Products? -cooking ware – old ceramics, poorly made metal ware -Degree of extractability is important -Cooking acidic foods is more dangerous -1/3 rd of toys here are toxic by EU regulations -a few times toys were removed from US Stores
http://www.environment.gov.au/atmosphere/airquality/publications/ceramics.html -Lead glazes are most commonly used on earthenware, and on older bone china and porcelain. -If they are not properly prepared and fired, lead may leach (i.e. move from the glaze) into food stored in or on the ceramic ware. -Acidic foods will accelerate any leaching. -Ceramic ware with a corroded glaze is extremely dangerous. -Reheating coffee in an old mug in the microwave is a particularly risky thing to do. Porcelain
Cooking Ware/Archeology Fall of Roman Empire – one theory of several The presence of lead in the drinking water leached in from the water pipes, glazes on containers that came in contact with food and beverages, and food preparation techniques could have contributed to heavy metal poisoning. It was also absorbed through the pores, since it was used in cosmetics.
Roman use of leadRoman use of lead - as cosmetics, pipes, jewelry, curse tablets, utensils and cooking pots, and, of course sapa and defrutum (wine boiled down in lead pots) sapa and defrutum Roman use of leadsapa and defrutum
Lead levels in bones from the Imperial Roman period had up to 30 mg/kg, which is three times higher than the level the WHO considers "very severe lead poisoning."
Paint -lead in paint only found now in developing countries -essential and easy to mix can of paint -to process dried paint on a surface requires a more powerful XRF and results are qualitative Thai Paint with up to 5% lead Problem? Small children put pieces of old paint in their mouths. -price of renovation in USA
Previous Thermo Collaboration -processed 675 skin creams -33% of samples from beauty shops exceeded guidelines -up to 3%Hg Murphy, T.P., S. Lim, S.P. Huong, K. Irvine, S. Bayen, B, Kelly and K. Wilson. 2012. Application of Handheld X-Ray Fluorescence Analyzers to Identify Mercury in Skin Whitening Creams in Cambodia. J Health Pollut. 3:21-31
The spiked recovery used DMSO for good mixing. Quantitative for <2000 ppm Hg A reduced response for >2000 Hg but still useful. No certified reference materials available for this analysis. Skin Cream Validation -1
XRF Validation -2 Comparison of XRF and ICP-OES is fine Again, there were no certified reference materials for skin creams. There are several standard reference materials for fish etc. When possible use certified reference materials.
Other cosmetics warrant analysis, management -a blush containing 878 ppm of cadmium -users all reacted to it and passed to their friends
EnvironmentCanadaEnvironnementCanada Waste disposal - PVC pipe has 7000 to 9000 ppm of lead - Should not be burned without emission treatment - Similar concerns about future oil and gas industry wastes
Other Hydrocarbons, Thermal Thermal power plants to be fired by Khmer coal -Sulphur, Arsenic, mercury content? -risk of acidification in soft water environment -Mercury in natural gas?
Khmer Coal Units ppm, Khmer coal formed in freshwater, low Sulphur SourceMean SulphurArsenicMercury Preah Vihear, Cam. 841930ND Springfield USA 1 320009.80.12 Appalachian 1 USA28000 2 35 1 0.21 1 Wyoming USA 3 63002.60.13
Concerns with Coal The Cardamom mountains are granitic and thus they have little buffering capacity. Burning coal produces sulphuric acid. Without emission treatment acid rain from burning coal in such an environment could kill most plants and water life At least the sulphur content is not high
Fish Anemia Study -Some fish have more iron content than beef and could be used to treat anemia. -so far <30 species processed for [Fe]
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