DETERMINATION OF SUB-PPBV LEVELS OF FORMALDEHYDE IN AMBIENT AIR USINGGIRARDS REAGENT T-COATED GLASS-FIBER FILTERS AND ADSORPTION VOLTAMMETRY

Formaldehyde (HCHO) present in ambient air was trapped on a standard m inature glass fiber filter impregnated with Girard's reagent T (GRT). The formaldehyde hydrazone formed (i.e. the adduct of formaldehyde and Girard's reagent T, FGA) is desorbed from the filter with water and d etermined by adsorption voltammetry. Recovery of formaldehyde as the F GA from a 13 mm impregnated filter is 87-104% in the range 0.06-30 mu g of formaldehyde. This corresponds to 2.0-1000 mu g m(-3) in a 30 l a ir sample. The collection efficiency of the coated filter is greater t han 90%. The GRT-coated glass fiber filter can be sampled at a rate of up to 1 l min(-1) when the system is used in the active mode, and a d etection limit of about 1 mu g m(-3) (corresponding to about 0.7 ppbv HCHO at standard state) based on a 30 l air sample is obtained. Result s are given from measurements of formaldehyde in ambient air of both i ndoor and outdoor environments.