Improving continuous chemiluminescence determination method of formaldehyde in the atmosphere: reducing interference of acetaldehyde and others by using iodoform reaction

ABSTRACT

The continuous and selective determination method of formaldehyde (HCHO) in ambient air using chemiluminescence method has been developed. The counter current flow tube was used to collect gaseous formaldehyde. The major interferences of HCHO determination from acetaldehyde, ethanol, and ferrous ion were removed by applying iodoform reaction. Effect of acetaldehyde on chemiluminescence signal of formaldehyde at the same concentration was reduced from 19 to 0.3% by applying iodoform reaction. Subsequently, HCHO was online detected by measuring chemiluminescence produced from the reaction of HCHO, gallic acid, H₂O_2, and KOH. The limit of detection (S/N = 3) was 4.5 ppbv in air. The calibration graph was linear up to 6.25 ppmv. HCHO concentration measured by the present method showed good agreement with that obtained by the 2–4 DNPH-HPLC method.