Determination of Lead and Cadmium in Ceramicware Leach Solutions by Graphite Furnace Atomic Absorption Spectroscopy: Method Development and Interlaboratory Trial
Abstract:This method was developed to improve sensitivity and eliminate time consuming, evaporative pre-concentration in AOAC Method 973.82 and American Society for Testing and Materials method C738 for testing foodware. The method was developed using leach solutions obtained by leaching 9 differently decorated ceramic vessels with 4% acetic acid for 24 h at room temperature. Lead and cadmium concentrations in leach solutions were 0.005–17 600 and 0.0004–0.500 μg/mL, respectively. Concentrations were determined using peak area, phosphate chemical modifier (8.3 μg PO4 −3), and a standard curve for quantitation. Optimized pre-atomization and atomization temperatures were 1300 and 1800°C, respectively, for Pb and 1100 and 1700°C, respectively, for Cd. Characteristic masses (m o ) were 10 and 0.4 pg for Pb and Cd, respectively. Precision of repeated analyses of calibration solutions was ≤3% relative standard deviation. Precision of duplicate leach solution analyses on different days was 0–9% relative difference. Recovery from fortified leach solutions was 96–106%. Results obtained by this method agreed 92–110% with those of confirmatory analyses. Results of certified reference material solutions agreed 94–100% with certificate values. Pb and Cd limits of quantitation (LOQ) were 0.005 and 0.0005 μg/mL, respectively. Results from 3 trial laboratories for 4 leach solutions containing Pb and Cd concentrations of 0.017–1.47 and <0.0005–0.0864 μg/mL, respectively, agreed 89–102% with results of the author. Two attributes of this method were noteworthy: (1) Background absorbance due to organic matter was entirely absent from atomization profiles, making the use of short pre-atomization hold times (2 s) possible. (2) Instrument precision was excellent and only one determination per solution was needed. Acceptance criteria for quality control measurements and a practical procedure for estimating the method LOQ during routine regulatory analyses are described.
Document Type: Research Article
Affiliations: U.S. Food and Drug Administration, HFS 338, Center for Food Safety and Applied Nutrition, 200 C St, SW, Washington, DC 20204.
Publication date: May 1, 2001
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- The Journal of AOAC INTERNATIONAL publishes refereed papers and reviews in the fields of chemical, biological and toxicological analytical chemistry for the purpose of showcasing the most precise, accurate and sensitive methods for analysis of foods, food additives, supplements and contaminants, cosmetics, drugs, toxins, hazardous substances, pesticides, feeds, fertilizers and the environment available at that point in time. The scope of the Journal includes unpublished original research describing new analytical methods, techniques and applications; improved approaches to sampling, both in the field and the laboratory; better methods of preparing samples for analysis; collaborative studies substantiating the performance of a given method; statistical techniques for evaluating data. The Journal will also publish other articles of general interest to its audience, e.g., technical communications; cautionary notes; comments on techniques, apparatus, and reagents.
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