Solid Substrate Room Temperature Phosphorimetry for Determination of Trace Selenium Based on Catalytic Reaction Between Trace Selenium and Isatin

According to the academic thought that trace Se(Ⅳ) could catalyze the oxidation reaction between K₂S₂O₈ and isatin (Isa) causing the sharp quenching of the room temperature phosphorescence (RTP) signal of Isa. A catalytic solid substrate room temperature phosphorimetry (SSRTP) for the determination of trace Se (IV) has been established. This method has a high sensitivity (with a detection limit (LD) of 0.015 pg/mL), a wide linear range (4.00×10^–8~4.00×10^–6 μg/mL), the regression equation of the working curve was △I_P = 2.948 + 63.245 C_Se(IV)(pg/mL, n ??= 7), and correlation coefficient (r) was 0.9997. It has been applied to the determination of residual Se (IV) in practical samples. The results agreed well wirh those of ultraviolet spectrophotometry. The reaction mechanism of catalytic SS-RTP for the determination of residual Se (IV) was also discussed.