Robert Clifford (1), Dan Davis (1), Keith Long (1); (1) Shimadzu Scientific Instruments, Columbia, MD, U.S.A.


Plants concentrate metals by absorbing them from the soil in which they are grown. Some metals are beneficial and essential for life, whereas other metals are highly toxic and have negative effects at even the lowest levels. Because of their toxicity, quantification of these elements is needed. This poster will investigate the preparation and analysis for the heavy metals arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg) in Cascade hops using graphite furnace atomic absorption (GFAA) and cold vapor mercury techniques. Spike and recovery tests are performed at or below the analysis target levels to ensure the accuracy and sensitivity of the technique. Pre-dried and ground hops were added to a closed vessel microwave digest system with nitric acid, hydrogen peroxide, water and a stabilizer added to ensure the metals remained in solution for analysis. Samples were analyzed in the low parts-per-billion (ppb) range.

Robert Clifford received his bachelor’s degree from Glassboro State College, now Rowan University, in New Jersey, his master’s degree from Villanova in Pennsylvania, and his Ph.D. degree from George Washington University in Washington, DC. He has published and presented over 100 papers in the fields of food, pharmaceutical, environmental, energy, geology, material science, photonics, and marijuana. However, his true love is foods and beverages. His first chemistry job was as a summer intern at the Campbell Soup Company, where he was hired as a full-time employee. After he went back to graduate school he took another job as an intern at the FDA, where he was also hired as a full-time employee. After graduating with his Ph.D. degree he left the FDA for Shimadzu, where he has worked for the last 25 years. His current title is marketing manager of food and consumer products.

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