Electrodeposition is an electrolytic technique for determining precise copper content when the copper’s purity is between 99.75% and 99.95%. Electrodeposition is effective for testing fire, electrolytic, and chemically refined copper, as well as copper in copper-tellurium alloys. ASTM E53 serves as a general guide for this test. Chemists dissolve the sample into a sulfuric-nitric acid mixture, then apply a current to the mixture. The copper separates and deposits onto a tared platinum cathode. When the solution turns clear, chemists use atomic absorption techniques to verify the amount of copper that did not plate. Our experts combine this amount with the volume of plated copper to determine the sample’s total copper content. ASTM E121 outlines a similar technique for copper-tellurium alloys.