PHOTOTHERMAL CHARACTERIZATION OF THIN-LAYER CHROMATOGRAPHY PLATES

The potential of photothermal beam deflection spectrometry (PTDS), pho toacoustic spectroscopy (PAS) and photothermal radiometry (PTR) for th e characterization of thin-layer chromatography (TLC) plates with resp ect to the surface and in-depth distribution of different compounds in side the sorbent was investigated. Photothermal measurements of TLC ch romatograms of the Camag III test dye mixture demonstrate that accurat e and comparable values for thermal diffusivity of spots in chromatogr ams and of the sorbent can be obtained by PTDS and PAS. PAS has been d emonstrated to be the most reliable and least time-consuming among the three investigated techniques. Differences observed between the PAS s ignal and the phase-frequency scans obtained from the spots of the sam e compound on different TLC plates could be due to the irreproducibili ty of chromatogram development or the inhomogeneousness in different T LC plates. (C) 1997 Elsevier Science B.V.