Chromatography Forum

Can 2,4-dinitrophenylhydrazone derivatives of aldehydes, particularly that of formaldehyde, be quantified using GCMS? We have a GCMS and are looking into analyzing raw materials and products for their formaldehyde content. I see numerous papers and test methods which specify HPLC. Are the DNPH derivatives unstable to high temperatures? I know they can be used for melting points, but will they survive a 275 C GC inlet?

The other question would be if DNPH has a low enough boiling/melting point to be used in GC. It may not be volatile enough.

EPA Method 556.1 uses PFBHA 0-(2,3,5,6-PENTAFLUOROBENZYL)-HYDROXYLAMINE HYDROCHLORIDE as a derivitizing agent for GC/FID which should work for GC/MS also.

You will likely struggle with 2,4-DNPH derivatives and GC - even for formaldehyde.

I've used this and solid-phase microextraction to get H2CO:

https://www.sigmaaldrich.com/US/en/prod ... ich/194484

The idea was to load up a fiber (CX/PDMS) with reagent by exposing a fiber to the headspace of an aqueous solution of the reagent. Then, remove it and expose it to the sample for X amount of time. The derivatives are amenable to GCMS. I just used a flame but you could use MS. The trouble I had was that you can't get a tremendous amount of the reagent on a small SPME fiber so I had to expose the sample to the loaded fiber for very brief times (15-20 seconds). Otherwise, I risked running out of derivatizing agent on the fiber. In the end, I was able to determine H2CO in plywood with that procedure.

I am not sure if you have the capability to do headspace but we used this method in past with reliable results
https://resources.perkinelmer.com/lab-s ... dehyde.pdf

Kevin

Thank you all for your helpful responses. I will need to investigate this further.

Hello everybody,

For my very first post, I will be commenting on this one year old topic as it is very similar to what I'm trying to do.

I managed to come up with a GC-FID method to separate and detect DNPH-propionaldehyde derivatives and I was trying to devise a quantification method.
My problem is that, according to this article, aldehydes (except formaldehyde) and asymmetric ketones will produce two isomers when derivatized and the ratio of the cis/trans isomers might be light dependent.
It would not be a problem if the response factors of the isomers were the same but they should be different.
So far, it seems the ratio has been mainly the same. I even injected a solution before and after sun exposure. The ratio stayed the same but the signal was lower (this suggested the solution is not stable to light).

Would you have a suggestion on how to procede with a quantification method?
I usually do external standard calibration curves with added internal standard but I'm really puzzled on how to consider the possibility of having a variable isomers ratio.

Thank you.

We investigated this as well, and our conclusion was that DNPH derivatives of formaldehyde and glutaraldehyde were best assayed by HPLC.

We investigated this as well, and our conclusion was that DNPH derivatives of formaldehyde and glutaraldehyde were best assayed by HPLC.

Thank you for the answer.

Indeed, according to the article I mentioned, HPLC is better suited for this analysis. If the correct wavelength is selected because the isomers have different absorption spectra.
The thing is, the peak for DNPH-propionaldehyde is not too well resolved from the matrix with our LC method. Further development is needed I guess.

Alternatively, I could use GC-MS I believe.
The difference of response factors seen in GC-FID should not be a problem in SIM mode.
Am I wrong?

Can 2,4-dinitrophenylhydrazone derivatives of aldehydes, particularly that of formaldehyde, be quantified using GCMS? We have a GCMS and are looking into analyzing raw materials and products for their formaldehyde content. I see numerous papers and test methods which specify HPLC. Are the DNPH derivatives unstable to high temperatures? I know they can be used for melting points, but will they survive a 275 C GC inlet?

Just leaving this here for reference:
GC-FID - Application News from Shimadzu (Nº G327A)