When analyzing the heavy metal content of various substances, it is important know the total metal concentration, but also the oxidation state of the metals.  Some forms of metals are toxic while others are considered nutrients.  Atomic absorption spectroscopy is a valuable tool for determining total metal content but cannot differentiate between different oxidation states. This presentation describes several undergraduate research projects that have analyzed the heavy metal content in everyday items such as drinks and cosmetics.  Recent news articles have questioned the safety of consuming a Moscow mule, a popular drink traditionally served in a copper mug, claiming that toxic copper leaches from the mug into the drink.  The articles led us to many questions: how much copper dissolves in a drink from a copper mug? How long does it take for a significant amount of copper to dissolve? What affects the amount of copper dissolved? What is the oxidation state of the copper?  How does the amount and form of dissolved copper compare to levels considered toxic.  Using atomic absorption spectroscopy, the amount of copper dissolved from a copper mug is determined as well as variables that affect the dissolution (pH, alcohol concentration, temperature, time).  Additionally, experiments were performed to determine whether the primary copper content was copper (I) or copper (II).  Another metal whose oxidation state affects toxicity is chromium, in which trivalent chromium is a nutrient but hexavalent chromium is toxic.  A variety of lipstick samples were analyzed using atomic absorption spectroscopy for heavy metals, specifically chromium and lead.  Multiple lipsticks were found to contain elevated levels of chromium.  However, the oxidation state of chromium was unknown.  Using a colorimetric assay, the form of chromium in the lipstick samples was characterized.

Toxic Moscow mules? Dangerous lipsticks? Analyzing the metal content in everyday items

255th National Meeting (2018)

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