Close-up view of a Perkin-Elmer Model 503 Atomic Absorption Spectrophotometer in use at the Kellogg Company Quality Assurance laboratory located in Battle Creek, Michigan. At the laboratory, atomic absorption spectroscopy was commonly used to analyze food samples for heavy metal content, part of Kellogg's efforts to maintain standards for purity and nutritive levels in its food products, as well as satisfy governmental nutritional labeling requirements.