Direct environmental lead detection by photoluminescent perovskite formation with nanogram sensitivity

Although the global ban of leaded gasoline has markedly reduced lead poisoning, many other environmental sources of lead exposure such as paint, pipes, mines, and recycling sites remain. Existing methods to identify these sources are either costly or unreliable. We here report a new sensitive and inexpensive lead detection method that relies on the formation of a perovskite semiconductor. The method only requires spraying the material of interest with methyl ammonium bromide and observing whether photoluminesence occurs under UV light to indicate the presence of lead. The method detects as little as 1.0 ng/mm² of lead by naked eye and 50 pg/mm² using a digital photo camera. We exposed more than 50 different materials to our reagent and found no false negatives or false positives. The method readily detects lead in soil, paint, glazing, cables, glass, plastics, and dust and could be widely used for testing the environment and preventing lead poisoning.