lsmith wrote:
mathiue and 70ev- Thanks for your input. I have removed the analyzer at least 5 times to change filaments and multipliers and every time I let it pump down for at least 1-2 days before making an initial test. It was then left on for 2 - 3 weeks before shutting off and the baselines were consistent - even when the peaks were in the 300 height range baseline is good. I also make ion guage readings each time.
I pulled off a valve from a junk analyzer and upon observation was surprised how small the restricted side is. You will need a dissecting microscope to really examine it.
Introducing a test solvent from a column is a good idea. I will have to order more supplies (column nuts, gold seal, ect.) Right now the GC has only been
used to provide the connection to the transfer line DET B set to 280C. The GC temperature readings communicate perfectly with Chemstation.
I will start to order supplies and will try to find a new valve.
The orifice will be very small, it is there to prevent the liquid from being drawn into the analyzer, only the headspace gas should enter and in very small amounts, so that is probably good.
Another test you could try would be to loosen the inlet cap with blank ferrule and allow a small amount of air to enter, then retighten it and after 5-10 seconds scan and see if the air and water peaks are present.
The only problem with some of these very old MS would be the condition of the capacitors on the boards. If you can pull the boards and look at the ends of the cylindrical capacitors, look to see that the ends are flat and not swelling outward.
When you get the low response with the PFTBA open, does it give sharp peaks with low heights or just noisy grass peaks where the peaks should be?