This method is for determining low concentrations of copperpresent as a hydrocarbon-soluble form in gasoline, kerosine andsimilar distillates. It is particularly useful on products thathave been copper sweetened. The lower limit of detection is 5 μg ofcopper per liter of sample (approximately 6 parts per billion).Silver and bismuth may interfere. However, the presence of thesemetals in a sample of hydrocarbon is unlikely. The complexationwith ethylene-diaminetetraacetate (EDTA) and citrate preventsinterference from all other metals.