Chromatography Forum

Dear all,

I am searching for a GC test method for residual formaldehyde in herbal extracts, any suggestion appreciated.

Terry

The best method would be to react the formaldehyde with a reagent that allows analysis by HPLC.

Unfortunately after 30 years of trying to analyze formaldehyde in air and in other matrices by GC accurately, I have given up and have decided that LC is a better solution.

Formaldehyde is just too reactive and it even reacts with itself !

I cannot remember the chemical used at this time. You should be able to find it as you seek a HPLC method for formaldehyde. Simply allow the extract to come into contact with the reagent. Then inject the reagent onto a HPLC with UV detector. This reagent is used to measure formaldehyde in air over a period of time.

good luck and I wish my memory was better.

Rod

DNPH? There are standards for DNPH derivatized formaldehyde available if I am not mistaken.

I have seen it done directly but it is extremely challenging.

Best regards,

AICMM

The LC conditions have to be done just right to separate the derivative from the reagent.

Dinitrophenylhydrazine is the chemical in question.

I believe a tech note was published at Supelco.

best wishes,

Rod

Thank you for your information, I will try to get the reference.

Also look at kits to monitor air quality (formaldehyde). You might flow nitrogen/inert gas through your herbal extract to release the HCO into a formaldehyde trap (containing DNPH) which then would react and be extracted and measured by LC.

You could manually spike your extract for recovery studies in this manner.

best wishes,

Rod

I agree HPLC is a better approach. There is a report for analysis of formaldehyde in air by GC/MS. The method is not as robust as method TO11.

http://www.entechinst.com/pdf/Formaldeh ... rAir04.pdf

chromatographer1, in addition to reactive nature of formaldehyde, what were the other challenges you had developing GC method?

Separation was not an issue, I had no interferences. But the reactivity and non-reproducibility were the real problems. The dimer and trimer of formaldehyde were also present and variable in their content.

Of course, an FID was not a suitable detector. Very low response. And the chromatographic system had to be both clean and inert, both column and sample injection system.

best wishes,

Rod