DEPTH DISTRIBUTION OF LIGHT STABILIZERS IN COATINGS ANALYZED BY SUPERCRITICAL-FLUID EXTRACTION GAS-CHROMATOGRAPHY AND TIME-OF-FLIGHT SECONDARY-ION MASS-SPECTROMETRY

The depth distribution of light stabilizers in coatings has been inves tigated by analyzing the stabilizer content of microtomed slices cut p arallel to the coating surface. The analytical technique consists of e xtracting the unbound light stabilizers from each microtomed slice and determining the stabilizer concentration of the extract, Extraction w as carried out using supercritical fluid, which yielded efficiencies a s high as 96% with relative standard deviation of 4%. Samples in the 1 -3 mg weight range were extracted. The extracts were analyzed using ga s chromatography/nitrogen thermionic detection and time-of-flight seco ndary ion mass spectroscopy (ToF SIMS). In addition to analyzing the e xtract, ToF SIMS is also capable of analyzing the microtomed slices di rectly. Good agreement between results obtained with the chromatograph ic and ToF SIMS techniques was observed.