Catalytic solid substrate–room‐temperature phosphorimetry detection for trace cadmium with Cd2+–3.5‐generation polyamidoamine dendrimer–Tween‐80 complex

Abstract

3.5-Generation polyamidoamine dendrimers (3.5-G-D) emitted strong and stable room-temperature phosphorescence (RTP) on filter paper when Pb2+ was used as a heavy atom perturber. The RTP signal of 3.5-G-D was sharply enhanced upon the formation of 3.5-G-D-Tween-80 micelle compound. The complex Cd2+ -3.5-G-D-Tween-80, generated in the coordination reaction between Cd2+ and the tertiary amidocyanogen on the outer layer of 3.5-G-D in 3.5-G-D-Tween-80 micelle compound, could catalyze KBrO3 to oxidize 3.5-G-D in 3.5-G-D-Tween-80, which caused the sharp quenching of the RTP signal of the system. The phosphorescence intensity change (ΔI(p) ) of the system had a linear relationship with the content of Cd2+. Thus a new catalytic solid substrate-room-temperature phosphorimetry (SS-RTP) for the determination of trace cadmium has been established. This highly selective and sensitive method has been applied to determine trace cadmium in biological samples with a limit of detection (LD) of 1.2 ag per spot (when the sample volume was 0.4 μL per spot, the corresponding concentration was 3.0 × 10(-15) g mL(-1) ), the results agreeing with those obtained by atomic absorption spectrometry. The mechanism of catalytic SS-RTP for the determination of trace cadmium was also discussed.