Used primarily for calibration and quality control in analytical testing of petroleum products. These standard samples ensure accurate measurement of physical and chemical properties such as viscosity, density, sulfur content, and distillation profiles in crude oil and refined fuels. They are essential in laboratories for validating instrument performance and maintaining compliance with international standards like ASTM, ISO, and EPA regulations. Widely applied in refineries, testing labs, and research facilities to monitor product quality, support regulatory reporting, and improve process efficiency.