Continuous fluorescence determination of formaldehyde in air

A flow method for the determination of formaldehyde in air is presented. A cylindrical wet effluent diffusion denuder (CWEDD) is used for continuous collection of formaldehyde from air into distilled-deionized water as denuder liquid. Collected formaldehyde in the denuder concentrate is on-line determined by fluorescence 2,4pentandione method. The collection efficiency of HCHO is quantitative at the air flow rate of 0.5 l min^-1. The calibration graph is linear in the range 2–300 (mu)g m^-3 HCHO. The limit of detection is 1.6 (mu)g m^-3 HCHO. The relative standard deviations for 2 × 10^-6 and 1 × 10^-5 M HCHO are 2.57 and 1.06%, respectively. Acetaldehyde, acetone, formic acid and acetic acid do not interfere. Delay of the signal is 2.5 min.