This method is for determining trace concentrations ofnon-volatile, hydrocarbon soluble forms of copper present ingasoline, naphtha, kerosene and similar distillates by eitherFlame-Atomic Absorption Spectrometry (Flame-AAS) or InductivelyCoupled Plasma-Atomic Emission Spectrometry (ICP-AES). It isparticularly useful on products that have been copper sweetened.The lower limit of quantitation is 5mg/kg (mass-ppb) copper. Themethod can be extended to other organic materials and concentrationranges. This method can be used in place of UOP Method 144.