Improved online coupling of planar chromatography with electrospray mass spectrometry: extraction of zones from glass plates

A plunger-based extraction device for HPTLC/MS coupling, which was originally designed for extraction on TLC aluminum foils, was enhanced. The threefold modifications enabled extraction of analytes from glass-backed HPTLC/TLC plates after separation. A buffering of the plunger reduced the occurrence of leakage. The involvement of a torque screwdriver for the fixation resulted in a reproducible contact pressure and avoided breaking the glass plates. The employment of this device was also extended to plates with a layer thickness of 100 mu m by reducing the height of the plunger's cutting edge. Repeatability of the extraction from glass-backed plates, linearity of the signal obtained, and detection capability were shown to be comparable to the original device, which was only usable with aluminum foils. The influence of the elution solvent on the intensity of the MS signal was demonstrated to be a compromise between high elution power of the solvent and good solubility of the analyte in the elution solvent. The extraction device was employed for plates from different lots and for plates with different stationary phases thereby proving its general applicability in planar chromatography.