Development of a quality assurance program for determination of ultratrace background levels of lead and cadmium in raw agricultural crops by differential pulse anodic stripping voltammetry.

Data on the background levels of lead and cadmium in the food supply are essential in order to establish a baseline from which to evaluate the extent of contamination in transport, processing, industrial atmospheric particulate fallout, and soil treatment (e.g., fertilizers, sewage sludge, etc.). This requires the establishment of site selection and sampling criteria as well as the development of a rigorous analytical method capable of performing routine analyses of Pb and Cd at ultratrace levels. The method used in this study, which was published previously, was designed to provide high sample throughput with minimal contamination. This involved control and measurement of blank levels and the establishment of quality control procedures to maintain confidence in the accuracy and precision of the method.