Chromatography Forum

I wish to callibrate my GC instrument using 40% Glyoxal.
on injection of a pure sample of the above, i get several peaks. Could anyone tell me how to do away with this problem?

please provide information

edit: instrument manufacturer/model, column type, what kind of inlet, detector, oven parameters, flow rate, etc.

The other peaks are probably from the 60% of the sample that is not glyoxal, or if you are working with the commercial 40% aqueous solution, possibly hydrates.

Before you worry about "doing away with this probelm" you need to think carefully about whether the extra peaks are telling you something useful about the sample.

Peter

The other peaks are probably from the 60% of the sample that is not glyoxal, or if you are working with the commercial 40% aqueous solution, possibly hydrates.

Before you worry about "doing away with this probelm" you need to think carefully about whether the extra peaks are telling you something useful about the sample.

Peter

So what could the usefull information be?
I know that Glyoxal is very unstable.
It polymerizes easily.
If this is the case, then how can I run a sample of the Glyoxal without it getting to change to another compound?

please provide information

edit: instrument manufacturer/model, column type, what kind of inlet, detector, oven parameters, flow rate, etc.

HP 6980 SERIES GC
COLUMN TYPE - HP-FFAB (CROSSLINKED FFAB) 30mm X 0.32mm X 0.25uM FILM THICNESS
INLET: SPLIT - SPLIT RATIO- 100: 1
FID
INJECTION TEMP - 200 0C
OVEN TEMP - 75 0C
DETECTOR TEMP - 220 0C
FLOW RATE - 1.0ml/min
N2, H2 AND AIR,

will this be ok?

The other peaks are probably from the 60% of the sample that is not glyoxal, or if you are working with the commercial 40% aqueous solution, possibly hydrates.

Before you worry about "doing away with this probelm" you need to think carefully about whether the extra peaks are telling you something useful about the sample.

Peter

So what could the usefull information be?
I know that Glyoxal is very unstable.
It polymerizes easily.
If this is the case, then how can I run a sample of the Glyoxal without it getting to change to another compound?

"So what could the usefull information be?" Presumably something connected with why you are running the analysis in the first place. What is the purpose of the analysis ?, what are your trying to find out that you do not know already ? What are you trying to measure ?

Peter

You can't.

Your title is a misnomer "GC analysis of pure glyoxal". This doesn't happen. By its very nature it has impurities. All you can do is see what oligomers exist and approximately how much.

You can purchase the di and tri oligomers as markers: (CAS# 4845-50-5) (CAS# 4405-13-4).

best wishes,

Rod

The other peaks are probably from the 60% of the sample that is not glyoxal, or if you are working with the commercial 40% aqueous solution, possibly hydrates.

Before you worry about "doing away with this probelm" you need to think carefully about whether the extra peaks are telling you something useful about the sample.

Peter

So what could the usefull information be?
I know that Glyoxal is very unstable.
It polymerizes easily.
If this is the case, then how can I run a sample of the Glyoxal without it getting to change to another compound?

"So what could the usefull information be?" Presumably something connected with why you are running the analysis in the first place. What is the purpose of the analysis ?, what are your trying to find out that you do not know already ? What are you trying to measure ?

Peter

ok, I am trying to obtain a calibration of the glyoxal on the instrument.
i will be running a reaction, and one of the products of the reaction is glyoxal. I will be running a gc analysis of the products to find out the %conversion of the reactant and the %yield of the glyoxal.

You can't.

Your title is a misnomer "GC analysis of pure glyoxal". This doesn't happen. By its very nature it has impurities. All you can do is see what oligomers exist and approximately how much.

You can purchase the di and tri oligomers as markers: (CAS# 4845-50-5) (CAS# 4405-13-4).

best wishes,

Rod

Yes, I acknowledge that the title was wrong. It would have been running pure Glyoxal on a GC.

What I am trying to do is to obtain a calibration of the glyoxal on the instrument.
I will be running a reaction, and one of the products of the reaction is glyoxal. I will be running a gc analysis of the products to find out the %conversion of the reactant and the %yield of the glyoxal. I hope this information should be able to guide in in helping me out with a possible solution.

You may not be able to calibrate your results to hard figures, but you should be able to trend the results nicely, and if you are looking for the optimum reactions conditions that should suffice.

You can estimate the amounts by assuming your peak of interest will have a similar FID response to another analyte of your choosing, an external standard. Acetaldehye comes to mind as a possibility. You may choose another more suited to your needs.

I hope this is helpful

Rod

You may not be able to calibrate your results to hard figures, but you should be able to trend the results nicely, and if you are looking for the optimum reactions conditions that should suffice.

You can estimate the amounts by assuming your peak of interest will have a similar FID response to another analyte of your choosing, an external standard. Acetaldehye comes to mind as a possibility. You may choose another more suited to your needs.

I hope this is helpful

Rod

Thanks so much for your response!
Does this mean that there is a perculiar problem with getting a clear and distinctive peak with running glyoxal on a GC? if so, then what can we attribute this to? I need to know this please.
Also, what will guide in my choice of an external standard?
Glycolaldehyde, glyoxal, glycolic acid, glyoxylic acid and oxalic acid are the likely products from the reaction that i will b analysing.
I am so expectant to hear from you once more.

This analyte and most aldehydes are very reactive. If water is in the mix, even more so.

Just injecting the aldehyde in a heated injector may induce reactions which may not be quanitative but may be reproducible.

I would investigate IC and wet chemistry methods to assist you in your research, as well as the possibility of headspace analysis.

best wishes,

Rod

This analyte and most aldehydes are very reactive. If water is in the mix, even more so.

Just injecting the aldehyde in a heated injector may induce reactions which may not be quanitative but may be reproducible.

I would investigate IC and wet chemistry methods to assist you in your research, as well as the possibility of headspace analysis.

best wishes,

Rod

Thanks once more for your submission on this issue.
I patiently wait for you as it appears you are ready to offer a truce on this dillema.
thanks once more.

I am still waiting as per the above subject matter.
Thanks in anticipation

This analyte and most aldehydes are very reactive. If water is in the mix, even more so.

Just injecting the aldehyde in a heated injector may induce reactions which may not be quanitative but may be reproducible.

I would investigate IC and wet chemistry methods to assist you in your research, as well as the possibility of headspace analysis.

best wishes,

Rod

Thanks once more for your submission on this issue.
I patiently wait for you as it appears you are ready to offer a truce on this dillema.
thanks once more.

please provide information

edit: instrument manufacturer/model, column type, what kind of inlet, detector, oven parameters, flow rate, etc.

Never heard from you again on this issue.
I have not resolved it yet!