Chromatography Forum

How soon after pump down is completed can you heat up the MSD on agilent 5973N?

How soon after pump down is completed can you heat up the MSD on agilent 5973N?

Immediately

thanks.
I am experiencing high air/water leak, ~6.03% & 18.87% respectively. I isolated the MS and re-check the a/w. It was about 7 & 10%. With the column re-attached the a/w was about 6, 12%. I baked out the MS via bake out program in chemstation, the a/w was about the same, 6 & 15%. However, the instrument I baked out the gc at 260 degrees C for ~1 hr. Roughly the same results for a/w. I checked for leaks at the door to the ms, between the ms and gc, at the x-fer line nut, the connection between the x-fer line and analytical column, the connection between the guard column and analytical column, the column nut and the retainer nut at the end of the end of the inlet body (which keeps loosening up). No leaks indicated.
If I have run the instrument with the leak, I get a few shots before I have to open up the ms to change the filament.
I refilled the calibrant vial recently, however the leak was present before but not as bad. Could that be a factor? Are there other problems that give a high a/w check, that may not truly be a leak? Is there another place in the system I should be looking for a leak?

I had a similar issue not that long ago and it was the O-ring thet seals the transfer line assembly to the MS box. It's kind of a pain to get to.

Thanks bigbear. I will look into that.

Also check the screws on the end plates, I have had to tighten those before. The four big Torx head ones at the front and back.