Strong Luminescence Catalytic Solid Substrate Room Temperature Phosphorescence for the Determination of Trace Copper

摘要

Under the conditions of reacting at 100°C for 8 min and irradiating with the infrared light for 15 min, methylene blue (MEB) could emit weak room temperature phosphorescence (RTP) on the cellulose acetate membrane (CAM) using Pb2+ as the ion perturber in the NH₃-NH₄Cl (pH=9.80) solution. MEB was oxidized by H₂O₂, which caused the RTP of the system to enhance. Cu2+ could catalyze the reaction of H₂O₂ oxidizing MEB, which caused the RTP of the system to enhance sharply. The ΔI_p (I_p0−I_p, the I_p0 and I_p were RTP intensity of the blank reagent and RTP intensity of the test reagent, respectively) of the catalytic system was 133.6, which was 4.1 times larger than that without infrared light irradiation (33.1). Its ΔI_p was proportional to the content of Cu2+. Thus, a new catalytic solid substrate room temperature phosphorimetry (SSRTP) for the determination of trace copper has been established. The limit of quantization (LOQ) of this method was 0.12 ag·spot−1 (sample volume: 0.40 µL·spot−1, corresponding concentration: 3.0×10−16 g·mL−1), showing high sensitivity. This method not only has been successfully applied to the determination of trace copper in the tobacco, tea and human serum, but also could predict human diseases. The catalytic reaction was first order reaction, whose activation energy (E) was 18.17 kJ·mol−1 and rate constant (k) was 3.4×10−4 s−1. At the same time, the mechanism of catalytic SSRTP for the determination of trace copper was discussed.