Hey guys! My name is Lígia and I work with GasBench II/IRMS (Delta V Advantage). We have a problem with our instrument. The water recorded by m/z 18 is around 20V. We checked the Nafions and they appeared to be fine, we heated the GC column to 100oC overnight, kept the heaters (Src heater and Inlet valve heater) on and it didn't improve. The instrument was turned off for almost a month and we have been trying to reduce this water for three weeks and nothing has worked. We make the peak center of the masses 18/32/40 before and after the ON/OFF standard test. We don't know what else we could do to reduce water in the system. Would anyone have a suggestion? Thanks
I suppose that you checked for leaks, without any GC gas entering the ion source ?
Yes, I checked for possible leaks and everything is fine in that regard. Only m/z 18 shows an intensity of 20V. Some users suggest running several standard ON/OFF tests, but doing this increases m/z 18 even more. The procedure I follow is to perform a peak center of the masses, conduct the standard ON/OFF test (40 runs), and then perform another peak center of the masses (18/32/40). Additionally, I keep the heaters on (src heater and inlet valve heater) after the standard ON/OFF test. The instrument has been showing this condition since 03 june 24. Before that day, I worked with carbonate samples.
I don't know this specific instrument so I can only suggest general checks. It also come to mind to check the pumping systems. If some pollution occurred to oil if mechanical primary pumps are used ?
The vacuum pump has recently undergone maintenance, which included an oil change, so I believe that is not the problem. But I really appreciate your suggestions, Dr. Jean-François.
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