agilent GC6890 MS5973 troubleshooting and grob mix

[calston]

im currently running in NCI and i test pesticides in a tobacco. the method i use is kinda dirty and i have alot of problems with my instrument. everytime theres a problem i have to completely clean instrument and MS source. this shuts down testing at least a day or two. got any suggestions to a grob mix that i can run to help pin point the problem or at least give me a idea.

ex. air leaks, water, etc?

[giacomo56]

Use a 5 meter retention gap before your analytical column.....it should help some.

[calston]

appreciate it.

[aldehyde]

Here is another thread where someone was having similar problems: viewtopic.php?f=3&t=13498

Of your analytes what is the highest level of concentration? What about sample clean up, do you filter/centrifuge etc?

Also, water and air will cause an NCI source to dirty up very quickly. After cleaning source and before tuning you should run methane pretune and check for peak 32 (air leak) and make sure that peak 19 (water that has been protenated by the methane) is small (at least no more than like 10% of 17). Once you're sure the vacuum is as free as possible of air and water then you should tune.

[calston]

appreciate the suggestions