A new fluorimetric method for the determination of formaldehyde in air based on the liquid droplet sampling technique

A new, simple, sensitive, selective and in-field fluorimetric method fur th e determination of formaldehyde is proposed. The reaction of formaldehyde w ith hydralazine in acidic medium, heating on a boiling water-bath for 25 mi n, produces s-triazolo[3,4-a]phthalazine (Tri-P). The fluorescence intensit y of the product formed (Tri-P) was determined lambda (em) = 389 nm with la mbda (em) = 236 nm. The fluorescence intensity is linear over a formaldehyd e concentration range of 1.3-33.0 mug l(-1). The proposed method was applie d successfully to the determination of formaldehyde sampled from the atmosp here using the liquid droplet technique. Formaldehyde vapour in a wind tunn el was produced by a mean of permeater. A linear curve was obtained between the concentration in the wind funnel and that in the droplet. The detectio n limit for formaldehyde was 2.0 mug l(-1) with RSDs varying from 3 to 12% in ambient air, using a droplet correction solution (boric acid and hydrala zine). The effect of interfering substances on the determination shows that most cations and anions did not interfere. The results obtained wen satisf actory compared with a reference method.