DETERMINATION OF FORMALDEHYDE BY HPLC AS THE DNPH DERIVATIVE FOLLOWING HIGH-VOLUME AIR SAMPLING ONTO BISULFITE-COATED CELLULOSE FILTERS

A method is described for the specific collection of formaldehyde as hydroxymethanesulfonate on bisulfite-coated cellulose filters. Following extraction in aqueous acid and removal of unreacted bisulfite, the hydroxymethanesulfonate is decomposed by base, and HCHO is determined by DNPH (2,4-dinitro-phenylhydrazine) derivatization and HPLC. Since the collection efficiency for formaldehyde is moderately high even when sampling ambient air at high-volume flow rates, a limit of detection of 0.2 ppbv is achieved with 30 min sampling times. Interference from acetaldehyde co-collected as 1-hydroxyethanesulfonate is < 5% using this procedure. The technique shows promise for both short-term airborne sampling, and as a means of collecting mg-sized samples of HCHO on an inorganic matrix for carbon isotopic analyses.