I've spent a lot of time under the hood as they say, tearing what little hair I have left out trying to troubleshoot weird, bizarre and downright impossible problems on GCMS equipment. GCMS equiment is some of most complicated commercially sold devices a person can deal with. Going down the wrong path can not only be costly but effect you lab productivity.
So, what have I learned over the years? Here's a general list of troubleshooting tips.
Rule 1: “Look for what has been changed.”
Many problems are introduced accidentally by human actions. Every time any
system is disturbed, there is a chance of introducing a new problem.
• If the MSD was just pumped down after maintenance, suspect air leaks or
incorrect assembly.
• If the reagent gas bottle or gas purifier were just changed, suspect leaks or
contaminated or incorrect gas.
• If the GC column was just replaced, suspect air leaks or contaminated or
bleeding column.
• If you have just switched ion polarity or reagent gas, suspect the tune file
you have loaded in memory. Is it the appropriate file for your mode of
operation?
Rule 2: “If complex isn’t working, go back to simple.”
A complex task is not only more difficult to perform, but also more difficult to
troubleshoot as well. For example, CI requires more parts to work correctly
than EI does.
• If you’re having trouble with NCI, verify that PCI still works.
• If you’re having trouble with other reagent gases, verify that methane still
works.
• If you’re having trouble with CI, verify that EI still works.
Rule 3: “Divide and conquer.”
This technique is known as “half-split” troubleshooting. If you can isolate the
problem to only part of the system, it is much easier to locate.
• To isolate an air leak, select Shutoff valve. If abundance of m/z 32 decreases,
the problem is not in the flow module.