Phosphorous, sulfur and chlorine are commonly analyzed elements in liquids such as petroleum products and organic solvents. For example, phosphorous is added to lubricating oils to prevent wear of gears under high pressure. Sulfur content in automotive fuel oils are regulated by the US environmental protection agency (EPA) and directives such as EURO VI to minimize air pollution due to automotive vehicles. Chlorine, contained for example in crude oil, is an unwanted element known for corroding oil processing installations and liquid transmission pipelines. To better meet demands of such applications, the benchtop wavelength dispersive X-ray fluorescent (WDXRF) spectrometer Supermini200’s analyzing crystal set has been newly reconfigured to optimize performance for trace level analysis of P, S and Cl. XRF analysis allows rapid and precise elemental characterization of such samples with minimum sample preparation. Laborious sample treatment such as acid digestion or serial dilution are not required. Liquid samples are simply poured into a plastic cup covered with film for measurement and results can be obtained in minutes. This application note demonstrates Supermini200’s performance for low level P, S, Cl in oil samples for both short and long durations.