Analysis of thin-layer chromatographic adsorbates by Fourier transform infrared photoacoustic spectroscopy

Abstract

Fourier transform Infrared photoacoustic spectroscopy (FTIR-PAS) Is used to analyze substances deposited on thin-layer chromatographic (TLC) silica gel plates. In spectral regions of high silica gel absorption, little structural Information Is derived. Regions of lesser absorption provide Infrared spectral Information of the adsorbate and Interactions between adsorbed species and the silica gel substrate. Detection limits of 1 ¿tg are reported for photoacoustic analysis of caffeine deposited on silica gel. The total time required for sample preparation and photoacoustic analysis was less than 5 min per sample.

Micro‐HPLC/TLC/FTIR

“…Although this problem isfairlyserious, there is nodoubt that this method offers an effective means of identifying the components of complex mixtures. The sample size used in this experiment, i.e., 2-1 6 pg/component, is comparable to those previously reported for DR and photoacoustic [22] measurements inTLCIFTIR. It has been found that one thousand scans are required to be coadded before a high-quality spectrum is obtained from sub- Filespectraofthecomponentsof thetest mixtureinFigure6.Spectraare numbered to correspond with the peak no.…”

Pharmaceuticals and Drugs

“…Analysis of TLC spots by photoacoustic spectrometry (TLC/PAS) has been preferred over DRIFT analysis of strongly IR-absorbing samples (123). The spot containing 1-50 /Jig of the sample must be removed from the chromatoplate.…”

Analysis of a Benzamide/Cholesterol Mixture by Using TLC/FTIR Technique

“…This approach is quick, convenient, and free of the risk of sample loss, since FTIR spectrum is directly obtained from the separated sample spot on a TLC plate. Subsequently, Griffiths et al [9,10], Zuber et al [11], Lloyd et al [12], and White [13] adopted various spectral techniques to develop a more practical in situ TLC/IR technique. However, the biggest problem of the in situ TLC/FTIR is that traditional TLC stationary phases, such as silica and alumina, exhibit strong background absorption that can bring about significant interference to sample identification.…”