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Cadmium Levels in People. Matthew Marah CHEM 4101 Dec. 9 th , 2011. Analyte : Cadmium (Cd). MW=112.41 g/ mol Most common oxidation state is Cd 2 + Mostly used in Nickel-Cadmium Batteries and electroplating Often a by-product of Zinc & Copper smelting. Problem.
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Cadmium Levelsin People Matthew Marah CHEM 4101 Dec. 9th, 2011
Analyte: Cadmium (Cd) • MW=112.41 g/mol • Most common oxidation state is Cd2+ • Mostly used in Nickel-CadmiumBatteriesand electroplating • Often a by-product of Zinc& Copper smelting
Problem • Long-term and high Cd exposure have a negative impact on health. A Cadmium leak from a plant could cause great damage to people nearby. • Health Effects Include • Kidney and liver damage • Respiratory troubles • Fatal at high exposure
Hypothesis • People who live closer to an industrial plant, that uses Cd or produces it as a by-product, will have higher levels of Cd in their blood than people living further away.
Sampling & Standards • Collect blood from people within 100 miles and between 200-300 miles of an industrial plant • Common levels of Cd range from ppb to ppm • Acceptable daily intake of 1µg of Cd/kg of body weight • Permissible Exposure Limit (PEL) = 0.05mg/m3 • Prepare standards of Cadmium from 0.01-10 µg/L for calibration Curve
Chosen Method: AAS Procedure Select wavelength range and collect data • Cd absorbs at 228.8nm & use PMT to amplify Digest sample with HNO3 (Nitric Acid) Dilute with 2M ammonium acetate to pH of 5.5 Atomize sample Possible Interferences • Other resonant lines • Sample Matrix • Combustion Products • Low volatility components • Dissociation equilibria • Ionization equilibria
Equipment Used WFX-210 AAS Spectrometer • LOD ≤ 6 µg/L • LOQ ≈ 1 µg/L • Precision ≤ 3% for Cd • Flame & Graphite Furnace atomizer • Wavelength Range: 190-900nm • Photomultiplier Tube (PMT) • Autosampler built-in
Conclusion • Based on experiments done outside the U.S., the use of AAS for analysis of Cd in the blood appears to be a sound and common choice. • Higher levels of Cd are expected to be found in people living closer to the chosen industrial plants. However, the amounts are still expected to be in the µg/L range. • A few trial runs could be attempted using pure blood samples to test the necessity of sample preparation for the experiment.
References • Center for Disease Control: Agency for Toxic Substances & Disease Registry. http://www.atsdr.cdc.gov/toxprofiles/tp.asp?id=48&tid=15 • Crouch, Stanley R.; Holler, F. James; Skoog, Douglas A. Principles of Insrumental Analysis, 6th ed.; Brooks/Cole: Belmont, CA, 2007. • Energy Research Centre of the Netherlands. http://www.ecn.nl/docs/society/horizontal/hor20_AAS.pdf • Environmental Protection Agency. Technology Transfer Network: Air Toxics Web Site. http://www.epa.gov/ttnatw01/hlthef/cadmium.html#ref1 • Qualitest International Inc.: Atomic Absorption Spectrophotometers. http://www.worldoftest.com/wfx-210.htm • Weston, Andrea; Brown, Phyllis R.; Jandik, Pter; Jones, william R.; Heckenberg, Allan L. Factors affecting the separation of inorganic metal cations by capillary electrophoresis. Journal of Chromatography1992, 593, 289-295. • NSF International. NSF International Web Site. http://www.nsf.org/business/newsroom/pdf/DS_Metal_Contaminant_Acceptance_Levels.pdf • The Physical and Theoretical Chemistry Laboratory Oxford University. Chemical and Other Safety Information. http://msds.chem.ox.ac.uk/CA/cadmium