ASTM 2668 and IEC 60666 are the standard test methods, using infrared spectroscopy (IR) technology to monitor the concentrations of DBPC and DBP in electrical insulating oil. These test methods are used to determine if the new electrical insulating oil meets the specification for oxidation inhibitor initial concentration levels. They also monitor the concentration of inhibitors in the used oil. If the inhibitors have been depleted to a critical level, additional inhibitor can be added. Therefore, the standard test methods are essential for manufacturing control, specification acceptance, and to periodically monitor the level of inhibitors in used oils. Agilent Cary630 傅里葉變換紅外光譜儀