This method is for determining low concentrations of copper present as a hydrocarbon-soluble form in gasoline, kerosine and similar distillates. It is particularly useful on products that have been copper sweetened. The lower limit of detection is 5 μg of copper per liter of sample (approximately 6 parts per billion). Silver and bismuth may interfere. However, the presence of these metals in a sample of hydrocarbon is unlikely. The complexation with ethylene-diaminetetraacetate (EDTA) and citrate prevents interference from all other metals.