2.2.2. Paper Spray MS

Paper spray mass spectrometry (PS-MS) was carried out using a home-built ion source consisting of an alligator clip and filter paper (Whatman No. 4, from laboratory stocks) electrode that was powered by the AccuTOF electrospray port. For the PS-MS, +3500 V was applied to the paper electrode, with the Orifice 1 and ring lens voltages set to +80 V and +10 V, respectively. The tip of the paper electrode was positioned in front of Orifice 1 on the AccuTOF. A 3 μL aliquot of the extract was placed on the paper electrode for analysis. PS-MS was chosen for analysis as the electrospray ionization source available in the EMU Chemistry Department required large volumes (20–50 μL) of sample.

Calibration of each data file collected on the AccuTOF from both DART and PS-MS was carried out with PEG-600 in methanol, and files were processed using TSS Pro 3.0 software (Shrader Analytical and Consulting Laboratories, Detroit, MI, USA). Further data analysis was undertaken with Mass Mountaineer software (various versions, RBC Software, provided by R. B. Cody).
