All,
I like this guide (
https://cast.desu.edu/sites/cmnst/files/document/1/schlenk_line_safety-5.pdf) by Pat Frank at SLAC (although I think he just retired). It does discuss and describe mercury, but clearly states that they are not permitted. I'm more of an analytical chemist by training, though, with no Schlenk-line experience outside of lab classes, so I'm less likely to catch any faults than those with more experience.
Sincerely,
Jack Reidy (he/him)
Research Safety Specialist
Environmental Health & Safety
Stanford University
484 Oak Road, Stanford, CA, 94305
Tel: (650) 497-7614
I have to say that I was really excited when I saw and read through this guide that Neal alerted us to. Having done my graduate research using high vacuum and Schlenk line techniques and seeing so many others struggle to do the same I thought this was a great introduction to this tool that is accessible and in a form that many young scientists will appreciate.
Craig's comments about some of the missing detail and safety details struck me as correct, but misdirected. This is most definitely a guide and not a treatise on the subject -for that I would recommend The Manipulation of Air Sensitive Compounds" by Shriver and Drezdzon- Wiley 1986- with the side note that I believe Neal worked in Shriver's lab way back when. However, when I pulled my copy off the shelf last night- I noted that it also discussed use of mercury devices including mercury diffusion pumps (but it does have a paragraph of info on mercury hazards later in the book).
So my question to Craig and the group is- is there a better guide on this subject that is as accessible/available and has the appropriate safety information that we could recommend instead? I am not aware of one and would suggest not discounting this guide but rather reaching out to the author and providing him this safety information to supplement his already good guide and make it better.
Joe Pickel
This Schlenk line guide is a bit simplistic and old-school. For example:
"The inert gas is vented through a bubbler (either oil or mercury).-
". Really? mercury bubbler? We should only be recommending oil.
Rest of same sentence: "allowing the inert gas pressure to be monitored."
Not really. It does allow one to see the flow of inert gas, but not truly monitored. The function of the bubbler is to provide a small positive pressure so when one releases an evacuated flask to inert gas the system should not have negative pressure and suck in oil/air.
Missing from diagram - Since a taller column of oil is necessary to achieve the same positive pressure of inert gas, a trap should be placed between the inert gas manifold and the bubbler to catch oil moving towards the inert gas manifold.
Missing from diagram - An inert gas ballast should be connected to the inert gas manifold. My students use a 1 L flask so that when a larger evacuated flask is switched to inert gas the drop in inert gas manifold pressure is not so great as to suck oil back into the system. Too much pressure reduction and air could be sucked in after the oil.
The guide does not include information about usage, mainly just startup and shutdown. So maybe a starting point, but not a guide to usage.
Craig
Craig A. Merlic
Professor of Chemistry, UCLA Department of Chemistry and Biochemistry
Executive Director, UC Center for Laboratory Safety
Los Angeles, CA 90095-1569
ASYNT has updated its SCHLENK LINK SURVIVAL GUIDE. Very helpful for those new to vacuum techniques or as a sanity check for the pro.
Stay healthy and stay safe
Neal
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