ABSTRACT
Thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) are widely used for separations involving nonvolatile organic molecules. HPLC is usually considered the method of choice for nonvolatile mixture-component separations. However, there are a number of commonly overlooked advantages of TLC for these applications. Separated species can be detected visually after spraying the TLC plate with a substance that reacts with components to form colored spots. The automated sample transfer interface constructed by Shafer et al. represents a significant advance in TLC/Fourier transform infrared spectroscopy (FT-IR) technology. FT-IR/Photoacoustic spectra for TLC eluents are obtained by measuring the spectrum of the eluent adsorbed on the stationary phase and subtracting spectral features corresponding to the stationary phase. TLC eluent locations must be known in order to employ these selective extraction techniques. Diffuse reflectance FT-IR is well suited to the highly scattering nature of stationary phases commonly employed for TLC.
