Chromatography Forum

Evening,

I'm in the process of doing some comparisons to my own research and am trying to figure out why this particular product was not mentioned in this paper when during a duplicate experiment I performed it was produced in great quantities. The chemical in question is formaldehyde - in this paper it looks like a liquid analysis was performed using a supelcogel-H HPLC column with a refractive index detector with 0.1% phosphoric acid as the eluent. Is it possible that formaldehyde is unable to be detected by an RI? or is it more likely that their method was not run long enough to reach the retention time of the HCOH? In this paper acetic acid and methanol were also successfully analyzed using this column and whatever method they used. Any wisdom would be greatly appreciated.

thanks!

Dear Kbrodw01,

If you prefer to avoid RID read this article <http://www.fda.gov.tw/files/publish_periodical/3_18.pdf>
which maybe may help you.

Hoping for the best,

Carlos de Souza Teixeira

Actually, formaldehyde should elute before acetic acid on that type of column and is often difficult to separate from formic acid ( http://www.sciencedirect.com/science/ar ... 7301941500 ). If there is enough of it, it *should show up with RI detection. One possibility is that it was subsumed in the "t0 noise" and ignored.

Just throwing in another possibility- Often formaldehyde and other aldehydes are analyzed as DNPH derivatives with UV detection. Here are a couple examples using reverse phase columns:
http://www.restek.com/chromatogram/view/LC_0036/50-00-0
http://www.restek.com/chromatogram/view ... 93/50-00-0

The RI for 50% formaldehyde in water is 1.37 so it should be better signal than the methanol at equal concentration.

Hi; Formaldehyde is quite good detected using RID; I used this technic for fixation solution analysis.
UV detection by derivatization with DNPH is suitable and more sesitve, nevertheless I think this reagent is harder to find it; i always thought that use elechtrochemical detector could be a good option as well with out derivatization.

Regards.

Oscar