Determination of trace formaldehyde by solid substrate-room temperature phosphorescence quenching method based on the rose bengal-potassium bromate-Tween-80 system

A new method for the determination of trace formaldehyde by solid substrate-room temperature phosphorescence quenching method has been proposed. It is based on the facts that rose bengal (R) can emit intense and stable room temperature phosphorescence on the solid substrate of filter paper (SS-RTP). Potassium bromate (KBrO3) can oxidize R, which causes the quenching of RTP. In the presence of HCHO, it can react with KBrO3 to form Br2 and Br2 can oxidize R, which causes smart quenching of RTP. The phosphorescence intensity (ΔIp) is directly proportional to the concentration of HCHO. In the presence of Tween-80, the ΔIp will be increased to 9.1 times higher than that without it. The linear range of this method is 0.016-1.6 fg spot−1 (corresponding concentration: 0.040-4.0 pg ml−1, 0.40 μl spot−1) with the detection limit of 4.5 ag spot−1 (corresponding concentration: 1.1 × 10−14 g ml−1). The regression equation for working curve is ΔIp = 136.6 + 28.28mHCHO fg spot−1 (r = 0.9935, n = 6). This method is sensitive, simple, rapid and has been applied to the determination of trace formaldehyde in real samples with satisfactory results. The mechanism of determination of trace formaldehyde by SS-RTP quenching method based on the rose bengal-KBrO3-Tween-80 system is also discussed.