Determination of sub-ppbv levels of formaldehyde in ambient air using Girard's reagent T-coated glass fiber filters and adsorption voltammetry

Formaldehyde (HCHO) present in ambient air was trapped on a standard minature 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 determined by adsorption voltammetry. Recovery of formaldehyde as the FGA 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 air sample. The collection efficiency of the coated filter is greater than 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 detection 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. Results are given from measurements of formaldehyde in ambient air of both indoor and outdoor environments.