To achieve a better understanding of the "vinegar syndrome" phenomenon, which has caused serious damage to triacetyl cellulose-based motion picture films, the white powder obtained from damaged film surfaces was analysed in this study. The powder was found to be soluble in acetone, diethyl ether, dimethylformamide, and chloroform, but insoluble in water. From the results of 1H, 13C and 31P nuclear magnetic resonance spectroscopy, mass spectrometry, and X-ray fluorescence measurements, it was concluded that the white precipitate had a molecular weight of 326 amu and was composed of triphenyl phosphate (C18H15O4P).