MALDI-TOF Mass Spectrometry (using the MALDI-TOF instrument)

Sample prep

1. Pipette 1 uL of appropriate matrix onto MALDI plate. Allow to air dry for ~5 minutes.
2. Pipette 0.5 uL of protein, then 0.5 uL of matrix onto dried matrix spot from step 1. Pipette up and down to mix (gently, avoiding disrupting spot).
3. If your concentration is low, you can repeat step #2 several times to increase the total amount of protein on the spot.

Data collection

1. Turn on MALDI computer (MALDI instrument itself should be left on at all times to maintain vacuum. If it is off please contact Dan Graham). Also turn on the view screen for the plate viewer (the old cathode ray tube monitor with a circle drawn on it). 
2. Open Voyager software program
3. Hit eject/open (hand symbol)
4. Put the MALDI plate in holder (letters upside down, slide in from the right)
5. Select a plate template (i.e. DRG-plate2) then click the eject (hand) symbol. Machine will retract plate, be patient while it finds its place. 
6. Allow vacuum to reach 2e-6 Torr maximum. Make sure the vacuum is stable before proceeding further. 
7. Turn on the high voltage (lightning bolt symbol)
8. Load settings file (Harms-lab-default). Change settings as necessary for your experiment. 
9. Move to desired spot on plate and fire using the “fire” button (to the left of joy stick on control interface)
10. Save spectrum file to appropriate directory. 
11. Turn off the high voltage (click the lightning symbol again). 
12. Eject the plate (hand symbol). Again, be patient while the machine ejects. 
13. Retract the plate holder (use the hand symbol again). Then turn off the Voyager control software. 
14. Open spectra files in data explorer software and export as open-format ASCII files. The proprietary voyager files aren’t readable in any other software.
15. Copy data files onto an appropriate flash drive (newer flash drives may not be compatible with this ancient beast of a computer). 
16. Turn off the MALDI computer and view screen.