Determination of trace uranium by a photo-catalytic resonance fluorescence method coupled with dual cloud point extraction

[摘要] In this study, two types of salophens (SA) with different solubilities were synthesized, and they all can combine with uranyl to form stable complexes: [UO22+–SA1] and [UO22+–SA2]. Among them, [UO22+–SA1] was used as ligand to extract uranium in complex samples by dual cloud point extraction (dCPE), and [UO22+–SA2] was used as a catalyst for determining uranium by a photo-catalytic resonance fluorescence (RF) method. The photo-catalytic characteristic of [UO22+–SA2] on the oxidized Rhodamine G (RhG) by potassium bromate led to an RhG RF intensity decrease. The reduced value for the RF intensity of the reaction system (ΔF) was proportional to the uranium concentration (c), and a novel photo-catalytic RF method was developed for determining trace uranium(VI) after dCPE. The combination of photo-catalytic RF techniques and dCPE procedure provided enhanced sensitivity and selectivity to the present method. Under the optimal conditions, the linear calibration curves range was 0.040 to 40.0 ng mL−1. The limit of detection was 0.035 ng mL−1. The proposed method was successfully applied for separating and determining uranium in real samples with 91.3–107.3% recovery. The mechanisms of reaction and extraction are discussed.

[学科分类] 分析化学