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 investigated by analyzing the stabilizer content of microtomed slices cut parallel to the coating surface. The analytical technique consists of extracting the unbound light stabilizers from each microtomed slice and determining the stabilizer concentration of the extract, Extraction was carried out using supercritical fluid, which yielded efficiencies as high as 96% with relative standard deviation of 4%. Samples in the 1-3 mg weight range were extracted. The extracts were analyzed using gas chromatography/nitrogen thermionic detection and time-of-flight secondary ion mass spectroscopy (ToF SIMS). In addition to analyzing the extract, ToF SIMS is also capable of analyzing the microtomed slices directly. Good agreement between results obtained with the chromatographic and ToF SIMS techniques was observed.