Thermal probe based analytical microscopy: Thermal analysis and photothermal Fourier-transform infrared microspectroscopy together with thermally assisted nanosampling coupled with capillary electrophoresis

In this study, we have demonstrated that a scanning probe microscope (SPM) can be used for thermally assisted nanosampling (TAN) with subsequent analysis by capillary electrophoresis (CE). Localized thermomechanical analysis (L-TMA) and photothermal Fourier-transform infrared (PT-FTIR) microspectroscopy can also be employed using the same probe, thus illustrating how a single instrument can carry out a number of different complementary analytical measurements. Benzoic acid and 4-hydroxybenzoic acid were manipulated with a heated Wollaston wire probe and successfully deposited onto the surface of a piece of CE capillary tubing. The deposited samples were then separated with CE. L-TMA and PT-FTIR were also used to characterize these materials. We have also demonstrated how a nanosample of a nonparticulate material can be taken and then deposited onto the surface of an inert matrix. TAN of a nonparticulate material was explored using polyethylene as the analyte and fluorene as the matrix. These examples show that thermal probe techniques provide a versatile “tool box” of modes of analysis with the potential to analyze a wide range of samples in a spatially resolved way.