Agilent 5975T - first GC/MS purchase

Discussions about GC-MS, LC-MS, LC-FTIR, and other "coupled" analytical techniques.

35 posts Page 3 of 3
MSCHemist wrote:
the 73's and 75's have nearly identical EI sources and Restek and others sell those parts.


When you get right down to it, I'm not sure if there's much real world difference between a 5973N with a fast scan sideboard and something like a 5975C. The gap gets even narrower if you can put the 3-axis detector in the 73, although I haven't looked into whether or not that's possible.

The 75 looks newer/fancier and of course does have the nice glass window on the front so you can see if the filament is on, but that's probably the major difference in them. It's almost like Agilent finally decided that the 5973 had enough incremental upgrades that the could justify calling it a new model.

I love my 75, but honestly if I walked in to work on Monday and the department chair said "We need another GC-MS-go get us a good deal on one" I'd probably opt for an optioned-up refurb 6890/5973(which, the last time I asked back last summer, could be had for ~$35-40K) over a 7820/5975 or an 88xx/5977.
Can't put the triple axis detector on anything earlier than the 5975C.

The benefit of newer GCs is better support for capillary flow technology (backflush, splitters, etc.) Or fast chromatography with intuvo.

Not too much has changed with the design of the single quad MS because development work has been devoted to the TQ and QTOF. Main changes are the window (5975), TAD (5975C), some detector changes (5977), and newer source technologies -- extractor source (5977A) and high efficiency source (5977B.) The big benefit of these sources is more evident on a TQ than SQ, but they do have their place.

If you're running a method that doesnt have really demanding sensitivity requirements I would agree the 5973N is still very capable and if you can get a good price it makes a lot of sense.
While my 5975B was down to have the turbo rebuilt I transferred my main trace analysis (3-mcpd) to my 5973N (no SIM/Scan) and found no difference in sensitivity so I kept it on the 73 and devote the 75 to tricky flavor work. My 6890+ (jetdirect) 5973 diff is my solvent method workhorse.
Our oldest MS currently is a 1998 5973 Diff pump that had the electronics upgraded to use LAN instead of HPIB and that is the most stable instrument we have. It runs nonstop and never complains, and running drinking water volatiles we vent it about once every two years to replace filaments. Seems the newer models are more sensitive but give up a little stability to gain the sensitivity.

I have honestly yet to have any run as stable and as long as the old 5970 I began my career with.
The past is there to guide us into the future, not to dwell in.
I have someone at work who has a Thermo ISQ 7000. It's down now with a power supply board failure and a currently estimated lead time of 30 days to get it in. I have 3 department GC-MSs-my workhorse 7820-5975, the new Varian 3800-300TQ, and my "special project" 5890-5971.

The 7820-5975 is currently configured for a special project and has a somewhat temperamental wax column, so it's out. No one other than me wants to use the 300-MS until I get the autosampler working(that's another story).

So, with that in mind, until his ISQ gets fixed, he's going to be using the 5971. I spent today making sure it was in good shape and ready to go for him, and I was pleased that it tuned to 1400V without too much drift from the last time. It may frustrate me at times, but at the end of the day it just keeps trucking along.
35 posts Page 3 of 3

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