Chromatography Forum

Does anyone know of a good way to remove excess DNPH after derivatization. We are trying to use an ECD and DNPH messes everything up.

Wouldn't adding formaldehyde or a ketone react with excess 2,4-DNPH ?

Decades ago, we investigated 2,4-DNPH to assay for trace formaldehyde in consumer products, and I felt that HPLC produced better results, and was sensitive enough for our purposes (less than 5ppm in a finished product).

It is fairly easy to separate the reagent from the formaldehyde derivative (smallest derivative) by HPLC. Reagent comes out first on C18 with MeOH:Water mobile phase. Perhaps you could develop a simple solid-phase extraction cleanup where the reagent would pass through the stationary phase and retain your derivative. Then, you could elute the derivative and inject it.