Deuterium Exchange
2
9. The tuning procedure calibrates the mass axis. Choose the “FC-43 mass calibration” tuning
mode in the pull-down list box in the middle of the window. Make sure the check box to the left
of the pull-down list box is checked, and the other three check boxes are cleared. Click on Start
Auto Tune. The system will open the calibration valve on the MS. This valve allows the vapor
from a fluorinated organic liquid, FC-43, to enter the MS. The text box across the bottom the
screen shows the progress of the Auto Tune procedure. After the procedure is complete, check to
see that “Multipoint mass cal: completed” has been printed in the text box.
10. Click on the Acquisition button, at the far right of the MS control window.
RUNNING A SAMPLE
1. The status indicators should both be green and be labeled Ready and No Faults.
2. The system is ready to begin. The start of data acquisition is signaled by the mechanical
switch on the top of the injection port. When you press down on this switch with the syringe,
data acquisition will begin.
3. Remember to use only a blunt tipped, conical needle syringe, to avoid destroying the Merlin
GC inlet. Before the first use, flush out a syringe with methylene chloride. Be sure to eject the
cleaning solvent into a waste container. Do not eject back into the source bottle as it will
contaminate the entire bottle. Flush out the syringe at least 50 times with air to remove traces of
solvent.
4. Head Space Analysis: If you are doing head-space analysis flush out the syringe with your
sample vapor at least three times. Inject 2-3 uL of your sample by gently pushing the syringe
needle into the injection port on the top of the GC. Be sure to push straight down and guide the
needle in as it is very fragile and easily bent. Remove the syringe immediately after injection.
5. Solution Analysis: Inject 0.2-0.3 uL of your sample by gently pushing the syringe needle into
the injection port on the top of the GC. That’s correct—the syringe has just a tiny amount of
solution in it. Be sure to push straight down and guide the needle in as it is very fragile and
easily bent. Remove the syringe immediately after injection.
6. Note the data file name. This name will be listed in the upper-right corner of the acquisition
dialog window. It will be in a form such as “2000.40012.SMS.”
Ion Trap Mass specs are very sensitive. You must
be very careful not to overload the instrument.
If you are injecting just gases, no liquids, use step 4.
If you are injecting liquids skip to step 5.
