Thesis Title

Metal Dissolution From Silver Plated Flatware By Organic Acids

Author

Chad Ziegler

Date of Graduation

Summer 2003

Degree

Master of Science in Chemistry

Department

Chemistery

Committee Chair

Ralph Sheets

Subject Categories

Chemistry

Abstract

Many pieces of heirloom dishware and flatware continue to see occasional use. Because most flatware items are made of metal and ingestion of certain metals can cause serious health effects, the safety of using heirloom items must be examined. The goal of this effort is to determine the character and amount of matter that is extracted from silver plated flatware pieces when they are exposed to organic acids of the type and concentration commonly found in foods. Examples of heirloom flatware, including those composed of the nickel silver class of alloys, were exposed to 0.1M and 1.0M acetic, citric, and lactic acid at room temperature and 100°C. The resulting solutions were analyzed for metal ion content using a Varian Liberty 150 AX Turbo Inductively Coupled Plasma-Atomic Emission spectrophotometer with a PMT detector. Additional samples were exposed to 1.0M acetic acid before and after removing a portion of the plating, and a set of 4 samples was immersed in acid to determine variability of the resulting solutions within a single flatware pattern. Investigations were carried out to determine the effect on solution composition when aluminum anodes were in contact with the samples while submerged in acid. Flatware was also exposed to deaerated acid to examine the effect of oxygen on leachate solution composition. A small portion of several representative samples was dissolved in concentrated HNO₃ to determine the base alloy composition. All measurements were performed in a 0.1M acid matrix to minimize matrix effects. Representative samples were also analyzed using a Shimadzu AA680U Flame AA spectrphotometer for comparison to ICP data. Some of the samples examined yielded significant levels of Pb or Cd heavy metal ions in the acids and concentrations investigated.

Copyright

© Chad Ziegler

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