Detection Method of Heavy Metal in Hot-melt Road Marking Paint

The amount of hot-melt pavement marking paint is huge, among which heavy metals cause great pollution to the environment. China has just issued the standards for the limits and detection methods of harmful substances such as heavy metals, but there is still room for improvement in the detection methods of heavy metals. The detection method of heavy metals in hot-melt pavement marking coating was established, which was different from the standard. First, the digestion system of nitric acid, hydrofluoric acid and hydrogen peroxide in hot-melt pavement marking coating was determined by orthogonal test. Second, four kinds of heavy metals (Cr, Cd, Pb, and Sb) were detected by FAAS. Two parameters of fuel assist ratio (acetylene flow/air flow) and combustion head height were optimized. Finally, hydride generation atomic absorption spectrometry was used to detect arsenic and mercury. Three parameters of acid concentration, reducing agent concentration and pumping time were optimized. The recoveries of six heavy metals were 91.1% to 109.2%, and the detection limits were 0.011 mg/L, 0.052 mg/L, 0.025 mg/L, 0.033 mg/L, 0.272 μg/L, and 0.223 μg/L, respectively. Results show that the method is suitable for the detection of harmful substances in hot-melt pavement marking paint.