New interfaces for coupling TLC with TOF SIMS

Two interfaces have been tested for coupling thin-layer chromatography (TLC) with time-of-flight secondary-ion mass spectrometry (TOF SIMS). The first interface was formed by vacuum deposition of silver on to the chromatographic layer and on to a track formed by scraping the layer from the glass plate. The unmodified aluminum backing of a TLC plate (again formed by scraping adsorbent from the plate) was used as the second interface. TOF SIMS analysis of separated spot extracts on silver targets was performed for comparison of results. From TOF SIMS spectra it was found that although unmodified aluminum-backed plates result in a low background intensity the interface is not highly suitable because the analyte mass does not move suitably on to the interface. Transfer to the interface is irregular - the analyte spot becomes spread and does not occupy the same chromatographic position (R-F) on the interface as on the chromatographic layer. The positions of analytes tested on the silver-coated interface were regular, and three specific single ion intensities from the mass spectrum were obtained.