Chromatography Forum

Hi everyone,

We're setting up a lab and I wanted to see if we could hire someone here who can provide some general guidance. Thus far this forum has been one of the best resources and there are some really knowledgeable people here (eg. James_Ball, Consumer Products Guy, etc) so I figured this would be the best place to start.

At this point we're at final stages and now gathering our gas requirements for our HP 5890 GC-FID and 5890/5972 GC-MS.

I essentially need some guidance on deciding on best carrier gas to use, choosing H2 generators (vendor), etc. This will likely only be 1-2 hrs of phone support and it can be done remotely (ie. not on-site). Please contact me if your interested in this small newbie project at: fdscientist at outlook.com

Thanks so much.

Hi Lespaul

I feel sure that you can get all the support that you need from the forum members by posting specific queries and by looking back at previous posts on the same subject. - and it will be free

Details of your proposed analyses would also be helpful.

Kind regards
Ralph

Thanks GOM, I appreciate the input.

I know I can run queries all day on forums, but I feel it will take me 10x longer to find all the answers I need.

Also, as much as I love figuring out things out on my own by diving deep into technical books/manuals, their is imply no substitute for real world experience when speaking with a professional.

Are you planning to use H2 on the mass spec? If yes, you can't simply run H2 into your mass spectrometer without some modifications to the MS. I've never done it but I did listen to a webinar once that discussed it.

If I'm you, I'd just go with helium. Much easier.

Agree with banjo: while it can be done and people do it, I would not use H2 with a MS.

Thanks Jake and rb6banjo for your input.

I think I will go with Helium instead, as much as I like the idea of using H2 the risks out weight the convenience considering my lack of experience in this area.

If it were a 5973 it would not be a problem, just not sure about the 5972. I did try it once with a 5971, but was running volatiles and the BFB tune would not pass. 5975 has to have the correct magnet material to be compatible but it is possible. I run H2 a lot on my 7000 with no problems.

James, do you know how the sensitivity you get with H2 carrier gas compares to what you get using helium?

Depends on the application. You can't use the increased efficiency of H2 chromatographically since you can't increase the carrier flow as you would on a regular GC detector, you have to actually decrease the flow rate, or keep it equal to Helium. The vacuum gauge will read much higher pressures in the analyzer but some of that is due to the fact that most ion gauge tubes are calibrated for N2 and each gas will give a different value regardless of the actual pressure in the analyzer.

I was able to increase the sensitivity doing MRM since I can eliminate the Helium Quench gas when running Hydrogen carrier, which improves the vacuum. Tradeoffs are you have to watch to be sure you are not getting reactions with unstable analytes, but with things like PAHs and PCBs you shouldn't have to worry about it.

The new Self Cleaning Source(Jetclean) that Agilent is pushing now is simply a 0.1 to 0.3ml/minute hydrogen flow mixing with the column effluent just before it enters the analyzer, which works to scrub the source on a continual basis or as a flush at the end of the run. They even say it can be implemented on 5975s using a CI setup to introduce the H2.

The only application I have not been able to use H2 on is volatiles, since the H2 interferes with the BFB tune check by reaction which causes a high mass 96 value versus mass 95. DFTPP for semi volatile analysis I have had success with. You do have to let it system bake out for several days before the background will be low enough. The H2 scrubs out a lot of hydrocarbon and siloxane contamination that is left behind when running Helium.

Depends on the application. You can't use the increased efficiency of H2 chromatographically since you can't increase the carrier flow as you would on a regular GC detector, you have to actually decrease the flow rate, or keep it equal to Helium. The vacuum gauge will read much higher pressures in the analyzer but some of that is due to the fact that most ion gauge tubes are calibrated for N2 and each gas will give a different value regardless of the actual pressure in the analyzer.

I was able to increase the sensitivity doing MRM since I can eliminate the Helium Quench gas when running Hydrogen carrier, which improves the vacuum. Tradeoffs are you have to watch to be sure you are not getting reactions with unstable analytes, but with things like PAHs and PCBs you shouldn't have to worry about it.

The new Self Cleaning Source(Jetclean) that Agilent is pushing now is simply a 0.1 to 0.3ml/minute hydrogen flow mixing with the column effluent just before it enters the analyzer, which works to scrub the source on a continual basis or as a flush at the end of the run. They even say it can be implemented on 5975s using a CI setup to introduce the H2.

The only application I have not been able to use H2 on is volatiles, since the H2 interferes with the BFB tune check by reaction which causes a high mass 96 value versus mass 95. DFTPP for semi volatile analysis I have had success with. You do have to let it system bake out for several days before the background will be low enough. The H2 scrubs out a lot of hydrocarbon and siloxane contamination that is left behind when running Helium.

Hello James, do you think i could run H2 on a 7000 for PCDD/F MRM?
I'm actually using helium and a 2x injector, 2x column. They both go into a 2 holes ferrule to source and i keep 1ml/min the main column and 0.6 ml/min the other column.

Thank you for sharing your experiences.

I currently have a similar setup on my 7000 but using a Y connector and transfer line going into the analyzer. I set flow to 1-1.2ml/min on the active column and 0.4-0.5ml/min on the column I am not using. It works great.

If H2 doesn't react with the dioxins/furans, then it should work. If you just want to use the cleaning properties of H2, you can use it on the inactive column with low flow while using He on the main column at the same time.

I actually used two way switching valves that have a two in/one out configuration, were He is plumbed to one side and H2 is plumbed to the other side and I can turn the valve to choose the carrier gas I want. It is my research instrument so with that setup I can explore just about any combination of parameters for method development. When not in use I can set it to H2 with low flows to save on He and keep it clean.

I currently have a similar setup on my 7000 but using a Y connector and transfer line going into the analyzer. I set flow to 1-1.2ml/min on the active column and 0.4-0.5ml/min on the column I am not using. It works great.

If H2 doesn't react with the dioxins/furans, then it should work. If you just want to use the cleaning properties of H2, you can use it on the inactive column with low flow while using He on the main column at the same time.

I actually used two way switching valves that have a two in/one out configuration, were He is plumbed to one side and H2 is plumbed to the other side and I can turn the valve to choose the carrier gas I want. It is my research instrument so with that setup I can explore just about any combination of parameters for method development. When not in use I can set it to H2 with low flows to save on He and keep it clean.

Thank you, much appreciated. I'll give it a try.