Quantitative detection and impact evaluation of phthalate plasticizers in insulating oil

Phthalate is one kind of widely applied plasticizers, which can improve the plasticity of various materials. Phthalate plasticizers are also added in food, in which the content is strictly controlled. However, they were seldom investigated by electric power industry. Recently, phthalate plasticizers were found to be present in many in-service insulating oils of transformers during our daily supervision work. Herein, the determination and quantitative detection of phthalate plasticizers in insulating oil was performed by gas chromatography-mass spectrometer (GC-MS). Di-n-butyl phthalate (DBP) was detected to be the major plasticizer in in-service oil samples, and the undesirable effect of DBP on the function of insulating oil was further evaluated. Finally, the sources of these phthalates in insulating oil were explored.