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- Posts: 44
- Joined: Wed Jul 11, 2012 1:45 am
- Location: California
I've been experiencing a strange problem. One of my instruments has been having Chloromethane and Bromomethane contamination in the blanks at around .5ppb-1ppb. It only occurs only when MeOH is present, even the ~2ul present with the ISTD. If I turn off the ISTD there is no response for those two compounds.
I have directly inject the MeOH onto the GC with no contamination (we also run it on 12 other instruments). I have eliminated the autosampler by spiking MeOH into DI and injecting it into the sparge tube.
I have replaced the mount, spargetube, sample pathway lines, sonicated the union and the 6 port value and replaced the traps multiple times.
Any ideas would be appreciated, I am completely stumped.
I am using Tekmar stratum concentrator an Agilent 7890A GC and a 5975c msd.