A portable RGB sensing gadget for sensitive detection of Hg²⁺ using cysteamine-capped QDs as fluorescence probe

A facile one-pot method was proposed to synthesis cysteamine capped CdTe QDs with a high quantum yield 30%. In the synthesis process, nitrogen protection, ultrasonic treatment, and light irradiation were unnecessary. Additionally, potassium tellurite was used instead of Te powder as Te source, avoiding of the time-consuming Te powder dissolution process. The prepared QDs were found to be Hg²⁺ sensitive. The detection linear range for Hg²⁺ was from 5 to 300nM, and the detection limit was calculated to be 1nM. The detection mechanism was mainly ascribed to the electron transfer from cysteamine capped QDs to Hg²⁺, resulting in a fluorescence quenching phenomenon. In addition, we developed a portable RGB sensing gadget with the QDs as fluorescence probe for Hg²⁺ detection, and the linear range was from 5 to 200nM. Furthermore, the gadget was applied for Hg²⁺ detection in tap water sample. The results showed that the average recoveries in real tap water sample were in the range from 97.2% to 115.3%, which indicated that accuracy and precision were satisfactory for practical application requirements.