PHOTOACOUSTIC INVESTIGATIONS OF SECONDARY CHROMATOGRAPHIC EFFECTS ON TLC PLATES

Photoacoustic spectroscopy (PAS) was used to study the vertical concen tration distribution of compounds on TLC plates. The results suggest t hat under the given experimental conditions compounds exhibit irregula r concentration profiles in vertical direction and tend to concentrate in the uppermost 61 mu m thick layer. This irregularity was accounted for by photoacoustic probing of thicker sorbent layers what lead to a n improved linearity of calibration curves compared to those obtained by reflectance densitometry.