Hydrophobic Treatment Enabling Analysis of Wettable Surfaces Using a Liquid Microjunction Surface Sampling Probe/Electrospray Ionization-Mass Spectrometry System

摘要

An aerosol application procedure involving one or morencommercially available silicone-based products was devel-noped to create hydrophobic surfaces that enable analysis ofnotherwise wettable, absorbent surfaces using a liquid mi-ncrojunction surface sampling probe/electrospray ionizationnmass spectrometry system. The treatment process resultednin a hydrophobic surface that enabled formation of thenrequisite probe-to-surface liquidmicrojunction for samplingnand allowed efficient extraction of the analytes from thensurface, but did not contribute significant chemical back-nground in the mass spectra. The utility of this treatmentnprocess was demonstrated with the treatment of wettablenhigh-performance thin layer chromatography plates, post-nplate development, and their subsequent analysis with thensampling probe. The surface treatment process for differentnsurface types was described and explained and the effective-nness of the treatment and subsequent analysis was il-nlustrated using alkaloids from goldenseal (Hydrastis ca-nnadensis) root separated on a normal phase silica gel 60nF254S plate and peptides from protein tryptic digestsnseparated on a ProteoChrom HPTLC Silica gel 60 F254Snplate and a ProteoChrom HPTLC Cellulose sheet. Thisnsimple surface treatment process significantly expandsnthe analytical surfaces that can be analyzed with the liquidnmicrojunction surface sampling probe, and therefore,nalso expands the analytical utility of this liquid extractionnbased surface sampling approach.