Formaldehyde analysis - is this a good project

[soccerdad007]

Hi all,
Perhaps I should ask this in the sample prep section but it does involve analysis as well.

I have been asked to look at measuring formaldehyde in some semi solids at high ppb levels. This is one of those projects where I really want to help the academic but am not certain what I might be getting myself into!!!

Reviewing the literature indicates that formaldehyde is usually measured after derivatisation when gc is used. Is that the best way?

Does anyone have any tips/hints/ knowledge of formaldehyde measurement that they can share?

I also came across doing SPME using a fibre previously coated with the derivatising agent. Is that viable?

Thanks in advance
Kevin

[allene]

Hi Kevin,
As I know, the best method for determination of aldehyde compounds is HPLC (by Pre-column DNP derivatisation and UV Detection) which could be used easily for sub- ppb level determination of formaldehyde. Although GC can be used (commonly derivatization with PFBOA), ECD or MS detector is needed.

[soccerdad007]

Thanks Allene.
I will look up HPLC methods. Do you happen to know what sort of sample prep is typical to get the formaldehyde ready for the precolumn DNP reaction. I have a semisolid sample and wanted to avoid extensive prep, hence my idea to use SPME.

I do have access to both ECD and MS if needed. Is the PFBOA method straight forward?

Kevin

[allene]

What is your sample exactly? How much sample do you have?

[Steve Reimer]

I ran formaldehyde by method 8315 (DNP derivatized HPLC UV-vis) some years ago. The hardest part of the prep was making sure the derivatizing reagents were clean enough to get the blank to pass requirements. Formaldehyde is everywhere.
The actual sample prep was relatively quick and easy. On one Friday I had water samples arrive at 2pm and they were derivatized, extracted and on the instrument before I left at 4pm.

[rb6banjo]

Can you purge the HCHO out of the semisolid matrix? If yes, these might help you:

http://www.sigmaaldrich.com/catalog/pro ... &region=US

I have had good success with them. The derivatives are easily recovered from the packing with methanol. The HPLC analysis is quite simple. I use 60:40 methanol (isocratic) and a C18 stationary phase. The derivatives absorb strongly at 350 nm or so. GC analysis of HCHO is tough because it doesn't respond well in a flame. Other detectors are possible but it's still difficult to trap for sample introduction.

If you don't have a lot of other carbonyl compounds (aldehydes and ketones) that might interfere, the "Total Carbonyl" method might work for you. As I recall in my previous life in the petrochemicals industry, when the 2,4-DNPH derivatives are treated with strong base, they turn color (I think it was blue). The reagent does not turn color. You can monitor the color spectrophotometrically. Obviously, if you have other materials in your matrix that might interfere, this won't work for you.

Good luck.

[James_Ball]

I ran formaldehyde by method 8315 (DNP derivatized HPLC UV-vis) some years ago. The hardest part of the prep was making sure the derivatizing reagents were clean enough to get the blank to pass requirements. Formaldehyde is everywhere.
The actual sample prep was relatively quick and easy. On one Friday I had water samples arrive at 2pm and they were derivatized, extracted and on the instrument before I left at 4pm.

This is what we use currently and it works well. For solid materials we rotate over night in the same buffer used for TCLP extractions, then pass that fluid through the C18 Solid Phase Extraction tubes used for water samples. The DNPH solution is then passed through the cartridge to derivitize the formaldehyde and eluted with Ethanol and brought to a 10ml final volume which is then easily separated with a C18 HPLC column and UV detection.

[Consumer Products Guy]

We've been assaying formaldehyde in consumer products and raw materials for over three decades now.

For trace levels we use HPLC after DNPH derivatization. We tried GC and GC with derivatization back in the 1980s, weren't overly enthused.

Formaldehyde is everywhere.

Yep. And very reactive. Have to have good blanks for trace level analyses.

[soccerdad007]

Thanks for all the great advice everyone. Lots of things to think about especially the issue with getting good blanks

Due to available equipment and the like, we are firstly going to try a headspace GC-MS method that involves putting the derivatising agent in the headspace vial with the sample. It is based on an application note that Perkin Elmer published.

Will be you posted how we make out

Thanks
Kevin