A method is described for measuring the infrared spectra of submicrogram quantities of materials separated by thin-layer chromatography (TLC) without removing the sample from the plate. The use of programmed multiple development for the chromatography concentrates each spot of sample on the TLC plate by approximately a factor of 4 compared to conventional TLC. A Fourier transform infrared spectrometer equipped with a mercury cadmium telluride detector enables recognizable spectra to be measured in less than 10 s.
