GB/T 18608-2012 specifies a method for the determination of nickel, vanadium, iron and sodium in crude oil and residue by flame atomic absorption spectroscopy (AAS). The content of these metal elements in crude oil and residue has a significant impact on the refining process and product mass. Excessive levels can lead to equipment corrosion, catalyst poisoning and other problems. The standard provides an accurate detection process for the petroleum industry, helping practitioners to accurately grasp the element content, so as to optimize the production process, ensure equipment safety, and play a key role in the mass control and production of petroleum refining.