I have just been having a discussion with a colleague who claims that dissolving samples in acetone will destroy the column and it is dangerous, also that acetone should not be used for solvent blanks.
As I need to use acetone (or a polar solvent) for dissolution of my solutions, should I now not run my samples? Is it wrong to use Acetone on a GC?
By Anonymous on Tuesday, July 15, 2003 - 06:17 am:
As long as you are using a bonded phase there is nothing wrong with using acetone as a sample solvent in GC. The only concerns are its extreme volatility, possible sample concentration from evaporation but no real good reason not to use it. Personally I would see if the sample is solublwe in other less volatile solvents.
By Anonymous on Tuesday, July 15, 2003 - 06:37 am:
If you are using a packed column it is not a problem either.
You can dissolve phase and redeposit it further down the column if your phase is soluble in acetone. Is this a problem, no, not really.
Hexane and methylene chloride have been used with packed methyl silicone columns for a sample carrier solvent and what is PDMS soluble in? the same of course.
If you are using an unbonded capillary column then any solvent you use may strip the phase from the front of the column and redeposit it downstream.
Acetone can dissolve a great number of usually insoluble substances and can deposit them in your column when it vaporizes. That can be problem.
I would use another less likely problematic solvent if possible.
By Anonymous on Tuesday, July 15, 2003 - 06:59 am:
The column I have is a capillary HP5, as I am not that good with analytical chemistry, being a technician, am I still OK to use Acetone? I thought it was OK, but my colleague has a PhD, so maybe hes right?
By Anonymous on Tuesday, July 15, 2003 - 09:33 am:
PhD in Physics? HP5 is bonded phase. Run acetone to your hearts content.
By Anonymous on Tuesday, July 15, 2003 - 09:52 am:
One potential problem is the expansion volume in the injector. If you are using an Agilent with a 2 mm id splitless liner you may have backflash with acetone where you will not have with hexane. Other than that, there should be no column damage.
Try it and see are any issues, and you can download a vapor volume calculator from the Agilent web site or use the on-line calculator at Restek's web site to see if there are backflash issues. I have used acetone successfully in the past, even though it is not my first choice for a solvent.
ps I have a Ph.D., but that doesn't automatically make me right about everything I say.
By mbg on Tuesday, July 15, 2003 - 11:44 am:
I'm just a 3rd person eavesdropping who does GC/MS. Does this mean acetone shouldn't be used with WCOT columns? ie DB-5ms?
We regularly use MeOH for our polar samples on a DB-5ms column (5% phenyl PDMS). When you say low volatility, does that count?
By Anonymous on Tuesday, July 15, 2003 - 03:59 pm:
Also, should I notbe using acetonitrile for sample dilution, then>?
By Anonymous on Tuesday, July 15, 2003 - 04:02 pm:
Hi, original messag poster hhere, how do I get this across to my boss then? (He already thinks the sun shines outta this guy's ass).
Not really a GC question, rather communication!
Also, the PhD guy said ether is far better!! Again, ishe right?
By Anonymous on Tuesday, July 15, 2003 - 04:12 pm:
Acetone should be fine because as a vapor it will not dissolve your stationary phase. I agree with the previous poster that expansion in the inlet may be the only problem. Acetonitrile is fine, too. Ether is a terrible choice because it is explosive!
You can show your boss literature from the column manufacturer, if it shows your column is solvent rinseable, or communicate with your manufacturer's customer service people and show their response to your boss.
By Anonymous on Wednesday, July 16, 2003 - 04:09 am:
Isn't it appalling when some doctors think PhD spells God?
By Anonymous on Wednesday, July 16, 2003 - 05:30 am:
Sounds like your PhD guy got his degree long ago before bonded stationary phases were invented. Aside from the solvent expansion volume already noted, I can't see any good reason not to use acetone. I probably would prefer not to work with ether or acetonitrile if I could avoid it. Go to the Agilent, or Restek website and download a solvent vapor calculator. Maybe you can adjust your injection volume and other operating conditions to minimize the risk of backflash.
By Anonymous on Wednesday, July 16, 2003 - 07:00 am:
Original poster here, no he got his PhD last year, he is 27 and knows EVERYTHING. He even upset my colleague, a lovely unassuming lady, who has worked for our company for many years by calling her a "lesser chemist" as she didn't have "anyththing more to contribute only having a BSc).
By Anonymous on Wednesday, July 16, 2003 - 10:10 am:
Maybe he is a PhD but he is not a good person.
Maybe if you explain his ideas about why not to use acetone as solvent, we could discover again the GC !!!
By Brian on Thursday, July 17, 2003 - 03:11 am:
I had a colleague once who had a PhD and he developed for us a TLC method using methylene chloride and dichloromethane. He also couldn't understand why he was getting no peaks from his LC analysis, especially as he had just cleaned "all the white gunky stuff out, so it should be working fine...."
By Anonymous on Thursday, July 17, 2003 - 05:34 am:
OK, so he's a bufoon....
By Ron on Thursday, July 17, 2003 - 05:55 am:
OK, let's be fair here and not turn this into Ph.D. bashing. The guy would be a bufoon without any degree, unfortunately having the degree has upped his arrogance level.
By Anonymous on Thursday, July 17, 2003 - 07:17 am:
True, but how dangerous is arrogance and ignorance put together? In my experience whether PhD or no, VERY dangerous!
However, many PhDs I've met tend to be very messy, and have a similar attitude to Mr PhD "Lesser Chemist" above, as thy are used to PhDs and technicians picking up after them. (What's a glass washer? What's housekeeping?)
By Jason Ellis on Thursday, July 17, 2003 - 09:06 am:
Just to get back to the topic of compatible solvents: acetone is no problem with a bonded phase column. In fact, you could RINSE the HP-5 column you have with acetone and it wouldn't cause phase damage. Other solvents mentioned (methanol, acetonitrile, etc.) are fine as well. If the column phase is bonded and crosslinked, then there's not going to be a problem. This is a question I hear frequently and it is a leftover from the days of nonbonded columns.
So, the organic solvent you choose will not damage the column -- we got that out of the way. That said, the solvent you do use can be a good or bad choice depending on other things:
(1) Vapor expansion volume -- different solvents have different expansion volumes when vaporized in the inlet, and some have very large expansion volumes (ie. water!) and are notorious for causing problems. Under certain conditions you may experience "backflash" in the inlet and that will cause poor response/reproducibility and/or contamination of the inlet. Backflash is when the vaporized sample is larger than the volume of the inlet liner. The Agilent Pressure/Flow Calculator (free from the website) can calculate vapor volumes for you. Go to www.agilent.com/chem and click on Technical Support then User Contributed Software. The software's free to download and use, and is helpful in determining if there will be a backflash problem under a certain set of conditions.
(2) Problems can arise if your solvent polarity is very different than your stationary phase (ie. methanol on a nonpolar 100% PDMS phase). If you're doing splitless injections, then under certain conditions a solvent/phase polarity mismatch can cause peak shape problems (tailing, splitting, etc.). Normally this can be solved by the use of a retention gap.
If you'd like some type of "official" statement, please contact me directly and I'll see what I can come up with.
GC Column Tech Support
By Anonymous on Thursday, July 17, 2003 - 09:10 am:
To get back to the original subject, if I needed information as to whether or not a solvent was appropriate on the column I was using I would contact the technical support department of the company that manufactures the column in question. Almost all of the companies will be able to provide you with a detailed explanation of why or why not the solvent is appropriate, and in most cases they will send you a reply by e mail so you will have something in writing to justify continued use of the solvent. Also, if the method has been used for years without any problems that is also good evidence the solvent is appropriate. There are some issues with certain solvents as some, especially DMSO, will dissolve organic vapors in the air and will not give a clean blank, but with careful handling this should not be a major issue.
Finally, even though the situation is very frustrating these things have a way of sorting out on their own. If you and your other co-workers continue to be productive with the current methods and your Ph.D. develops new and exotic methods that do not produce results your boss will eventually figure out what is going on. Just be sure to document things so that if problems develop after methods change it is obvious what happened. And, if it is not a danger to yourself or others, run the methods EXACTLY as the Ph.D. wants.
By Anonymous on Thursday, July 17, 2003 - 02:48 pm:
By Anonymous on Friday, July 18, 2003 - 06:32 am:
Lets focus on the acetone question:
Acetone as a solvent should be fine, but be careful that it does not interact with some of your components in your sample.
Acetone will almost instantaneously react with amines (formation of Shiff bases). Their are other reactions as well, but my organic chemistry is a bit rusty :-)
By Anonymous on Friday, July 18, 2003 - 03:35 pm:
Acetone will strip the column bare