BSTFA and Dichloromethane

[sspolver]

Hey folks,

New to the board and new to GC. Looking forward to learning as much as I can and sharing what little I've got. Just wanted to ask a few quick questions, if you'd be kind enough to listen.

We are currently working with only a GC and the compounds we want to analyze are not volatile enough to be picked up (aldehydes and non free fatty acids). I'm planning on using BSTFA to silylate them to give them the volatility I need. Unfortunately, the samples need to be extracted from an aqueous phase using dichloromethane and then dried under nitrogen to extract the non-volatiles for treatment. I was just wondering if any of you know of any unfortunate byproducts or problems with GC results when BSTFA is introduced to an organic solution that contains dichloromethane. Also, if the BSTFA silylation of aldehydes and organic acids seems awry, do let me know as well.

Thanks in advance for the help.

-sspolver

[tlahren]

I would see no problems with your analysis of organic acids. I have a personal preference to MSTFA but BSTFA will work fine. I found that using an equal volume of ACN (MSTFA:ACN) aids in the derivatization process but it's not required.

However, none of these agents will derivatize aldehydes. Only hydroxyl group. Here's a quick guide on GC derivatization reagents. http://www.discoverysciences.com/upload ... 3to328.pdf

Hope this helps.

Ty

[sspolver]

Ty,

Thanks for the info. I discovered this:

http://digitool.library.mcgill.ca/R/?fu ... EN01-MCG02

which is what I'm basing my process on. I'm testing for syringaldehyde, sinapaldehyde, coniferaldehyde, and vanillin (with their corresponding oxidization induced acids). Looks like most of them have an OH group on their center benzene ring. Think it'll still work? Or should I opt out for a different treatment?

-sspolver

[Peter Apps]

Ty,

Thanks for the info. I discovered this:

http://digitool.library.mcgill.ca/R/?fu ... EN01-MCG02

which is what I'm basing my process on. I'm testing for syringaldehyde, sinapaldehyde, coniferaldehyde, and vanillin (with their corresponding oxidization induced acids). Looks like most of them have an OH group on their center benzene ring. Think it'll still work? Or should I opt out for a different treatment?

-sspolver

It might be worth trying the compounds underivatized - with a well deactivated system you might be able to get decent peaks.

Peter

[tlahren]

Actually, a coworker of mine used PFBHA for SPME on-fiber derivatization of phenolic aldehydes and it worked great. I think BSTFA will work with theses aldehydes as well but I haven't tried it.

It was done in this paper with MeCl2 as well. http://www.cellulosechemtechnol.ro/pdf/ ... .27-33.pdf This may be your best source of information. Let me know if you don't have access to it (I think it's free though).

Ty

[tlahren]

I just saw Peter's post. If you haven't tried it already (run the compounds underivatized per Peter's suggestion) this may free up a lot of unnecessary time and materials. I would try it if you haven't.

Ty

[sspolver]

It might be worth trying the compounds underivatized - with a well deactivated system you might be able to get decent peaks.

Peter

Peter,

Picking up a Supelco SP-2330 column. Think this will do?

Actually, a coworker of mine used PFBHA for SPME on-fiber derivatization of phenolic aldehydes and it worked great. I think BSTFA will work with theses aldehydes as well but I haven't tried it.

It was done in this paper with MeCl2 as well. http://www.cellulosechemtechnol.ro/pdf/ ... .27-33.pdf This may be your best source of information. Let me know if you don't have access to it (I think it's free though).

Ty

Ty,

Checked it out. Looks solid. Thanks for that.

-sspolver

[Peter Apps]

It might be worth trying the compounds underivatized - with a well deactivated system you might be able to get decent peaks.

Peter

Peter,

Picking up a Supelco SP-2330 column. Think this will do?
-sspolver

There's only one way to be sure - try it, you can't do any harm. Good luck.

Peter

[Consumer Products Guy]

Sp-2330 is great for fatty acid methyl esters. When we do trimethylsilylated fatty acids, we use DB-1 or DB-5 types phases.

[sspolver]

Sp-2330 is great for fatty acid methyl esters. When we do trimethylsilylated fatty acids, we use DB-1 or DB-5 types phases.

Sounds like the DB-5 is a more general purpose column that'll be able to cover a wider basis, right? Will it cover FAMEs too, if need be?