Determination of formaldehyde in air by ion-exclusion and ion-exchange chromatography with pulsed amperometric detection

Abstract

A method is presented for the determination of formaldehyde in air sample extracts containing aqueous sodium hydrogensulfite. Utilizing the unique properties of its hydrogensulfite complex, formaldehyde is separated from other sample components by ion-exclusion and ion-exchange chromatography, then selectively detected by amperometry at a silver electrode. Optimum sensitivity of detection was found to occur at +0.10 V versus a silver wire reference electrode using a strongly basic background electrolyte. Using ribose as an internal standard, a linear response (r² > 0.99) was observed for aqueous formaldehyde concentrations in the range 0.02–10.0 mg l^–1; detection limits of <1 ng for formaldehyde were obtained using a 50 µl sample loop. The short-term reproducibility was better than 5%(as RSD). Analysis of laboratory air by collection in impingers containing aqueous NaHSO₃ yielded results consistent with previous literature values.