Fluorimetric flow injection analysis of trace amount of formaldehyde in environmental atmosphere with 5,5-dimethylcyclohexane-1,3-dione.

A simple and sensitive flow injection method with fluorimetry and 5,5-dimethylcyclohexane-1,3-dione (dimedone) was developed for the determination of formaldehyde. Formaldehyde reacted with dimedone in the presence of ammonium acetate to form a fluorescence compound, which has an excitation wavelength at 395 nm and an emission wavelength at 463 nm. A two-channel flow system was assembled. Distilled water and 0.3% dimedone buffered at pH 5.5 were delivered at 0.7 mlmin(-1) and 100 mul of sample was injected into the carrier stream. The reaction was done in the reaction system designed newly, which consists of heating and cooling devices. The chemical reactivity with formaldehyde was excellent in the reaction system and selective. The calibration graphs were linear in the range of 25-100 and 5-10 ppb. RSDs (n=10) for 50 and 10 ppb formaldehyde were 0.6 and 3.4% and the LOD (S/N=3) was 0.9 ppb. The sample throughput was 20 h(-1). The method was applied to the determination of formaldehyde in gas sample evolved from adhesive agents and in living environmental indoor. The sensitive and selective method is useful for monitoring trace of formaldehyde in the environmental atmosphere.