The catheter tubes of medical silicon rubber were dipped in ethanol. The effluents were fractionated by thin-layer chromatography (TLC), and their fractions were analyzed by ion trap electrospray ionization mass spectrometry (ESI-MS). The ESI mass spectra resulting from the main TLC fraction, R1=0.5 showed that the effluents were determined to be poly(dimethyl siloxane) (8 to 20 mer) that is a main part of a silicon rubber. The spectra for the origin in TLC showed that poly(ethylene glycol) (4 to 10 mer and 14 to 18 mer) and poly- (propylene glycol) (19 to 36 mer) as an antistatic agent were identified
