Our lab has a HP1100 LC/MS fitted with a Whatman75-72 (Parker Hannifen)Nitrogen generator. The generator is supplied with clean dry air from and oiless compressor system. Our system has been operating for 3.5 year. I am looking for experienced LCMS chromatographers to recommend an improvement over our our current system...or a system that has worked well for them. We replaced the membrane 1 year ago and are on our 3rd compressor for our pump. Can anyone recommend vendors of pumps that can supply lots of air to satisfy the nitrogen needs of LC/MS.
Our building does not have a satisfactory house air supply so I currently keep the "quiet" pump in the same lab space as the LC/MS.

We formerly had a 75-72 operating with house air from an oil-less compressor (about 100 R&D employees). Then apparently that compressor needed replacement and our building services dufi (plural of dufusses) didn't ask any users for any input and purchased a standard-type compressor with an oil separator to save $$$ and installed it. Well, guess what, due to inadequate staffing, maintenance neglected to drain the oil separator, and the entire building's air lines are now contaminated with oil. Of course the oil ruined the 75-72 membrane as well, great cost savings for the company, and we had to purchase our own separate oil-free compressor and have it plumbed in. Whatman engineer came in and detailed which compressor we would need, but when that arrived, it couldn't supply the constant volumes needed for 75-72 and 1100, so that was shipped back for a significantly larger one. It crapped out during the warranty period so it was replaced. We pay about $1300 per year for quarterly maintenance from a local company now. Get a large air compressor, and higher pressures deliver higher purity nitrogen with the 75-72. We purchased oil separators for all our department air outlets, such as those feeding 1050 HPLC samplers, 5840 GC, 7671 GC samplers. Great company cost savings, huh?

Waters UK/Micromass recommended Peak Scientific [http://www.peakscientific.com] to us.

We have good experiences with Peak Scientific and a Micromass LC-MS/MS.

We use a Dmnick Hunter one in the lab to supply 6 different LC/MS systems. We have it in the lab for one year now and the quality as well as the reliability seems to be very high. I do have experience with the Whatman as well, but personally I prefer domnick hunter.
For the peak nitrogen generator I have to say that I would never again buy one. We had one for test purposes in the lab - it did not reach the promised flow rate - when opening this one (compressor included) I saw all the mess in front of me. The motor of the compressor was getting very hot (burnt my hand) - the compressor was just time controlled and not mass controlled. The flow (and with this nitrogen purity) was controlled by a hole with fixed diameter. For me that was enough.

regards

Stephan

Thank you all for your feedback. You have greatly increased my learning curve and introduced me to some other vendors that hopefully will ease my search for a better source of nitrogen!