Abstract: A sample plate for a MALDI process is provided which comprises an electrically conductive substrate having a hydrophobic coating whose thickness and hydrophobic character can be modified by changing the coating substrate and/or the concentration of the substrate. Different coating substances that have provided optimal performance of the sample plate for reproducible deposition and analysis by MALDI-MS and MALDI-MS/MS processes of analyte mixtures include synthetic waxes such as paraffin compositions, lipids, organic acids, silicon-containing compounds, silica polymers and natural waxes. Metal polishes that have been used to clean and regenerate plate surfaces have also provided a sample plate that has optimal performance for reproducible deposition and analysis by MALDI-MS and MALDI-MS/MS processes of analyte mixtures.

Abstract: A sample plate for a MALDI process is provided which comprises an electrically conductive substrate having a hydrophobic coating whose thickness and hydrophobic character can be modified by changing the coating substrate and/or the concentration of the substrate. Different coating substances that have provided optimal performance of the sample plate for reproducible deposition and analysis by MALDI-MS and MALDI-MS/MS processes of analyte mixtures include synthetic waxes such as paraffin compositions, lipids, organic acids, silicon-containing compounds, silica polymers and natural waxes. Metal polishes that have been used to clean and regenerate plate surfaces have also provided a sample plate that has optimal performance for reproducible deposition and analysis by MALDI-MS and MALDI-MS/MS processes of analyte mixtures.

Abstract: A mass spectrometer instrument for determining the molecular weight of labile molecules of biological importance, in particular heavy molecules, such as proteins, peptides or DNA oligomers, is disclosed. The instrument includes a MALDI ion source that is enclosed in a chamber with an inlet for admitting a gas and an ion sampling aperture for limiting gas flow from the chamber. The elevated pressure of the source in the range from 0.1 to 10 torr causes low energy collisions between the gas and the ions that can cause rapid collisional cooling of the excited ions, thereby improving the stability of the produced ions. The formation of clusters of ions (e.g., protein ions) with matrix materials is broken without fragmenting the ions by increasing the downstream gas temperature to between 150 and 250° C.