Best practices for single-laboratory validation of chemical methods for trace elements in foods. Part I--background and general considerations.

The metals subgroup of AOAC INTERNATIONAL's Community on Chemical Contaminants and Residues in Food has been engaged for the past several years in discussions concerning the requirements for the single-laboratory validation (SLV) of methods for the determination of trace elements in foods. This paper reviews the general guidance currently available related to validation of chemical analytical methods and current typical validation practices found in publications on the analysis of elements in food and other matrixes, such as environmental and clinical samples. Based on the available guidance on SLV requirements and a review of current practices in elemental analysis, a general approach based on best practices is proposed for SLV of a method for elements in food to demonstrate the method as "fit-for-purpose.

Analysis of food for toxic elements.

The levels of the toxic elements Al, As, Cd, Hg, Pb and Sn are routinely monitored in food to protect the consumer. Increasingly, the chemical forms of As and Hg are also monitored. Analyses are performed to enforce regulatory standards and to accumulate background levels for assessing long-term exposure.

Preparation and characterization of a suite of ephedra-containing standard reference materials.

The National Institute of Standards and Technology, the U.S. Food and Drug Administration, Center for Drug Evaluation and Research and Center for Food Safety and Applied Nutrition, and the National Institutes of Health, Office of Dietary Supplements, are collaborating to produce a series of Standard Reference Materials (SRMs) for dietary supplements.

Analysis of dietary supplements for arsenic, cadmium, mercury, and lead using inductively coupled plasma mass spectrometry.

The arsenic, cadmium, mercury, and lead contents of 95 dietary supplement products were determined using microwave digestion and high-resolution inductively coupled plasma mass spectrometry. Precision and accuracy were demonstrated by element recovery from 17 dietary supplements and replicates of 8 reference materials. The concentration ranges were as follows: arsenic, <5-3770 microg/kg; cadmium, <10-368 microg/kg; mercury, <80-16800 microg/kg; and lead, <20-48600 microg/kg.