Coupling ozone-based AOPs with DLLME for simultaneous determination of trace free antimony and total antimony in surface water

The traditional standard method for the determination of the heavy metal pollutant antimony (Sb) in water, 5-Br-PADAP spectrophotometry, involves the consumption of many kinds of chemical reagents and has low sensitivity. For highly toxic liquid and gas containing Sb(iii), this paper presents a green determination method based on UV/O₃ synergistic oxidation-malachite green-dispersive liquid-liquid microextraction (DLLME)-spectrophotometry, which can achieve the enrichment of a trace amount of antimony in water and high-precision detection. Using the selective complexation and color development of protonated alkaline dye and the solubility difference of the complexes involved, an enrichment and determination method for trace Sb(v) in surface water was established for the first time. Based on the feature of the UV/O₃ system of rapid and complete oxidation of Sb(iii), and the easy elimination of the disturbance of residual oxidant, the green determination method for trace total antimony (TSb) was constructed based on advanced oxidation processes (AOPs). To verify the validity of the proposed method, all the process parameters and environmental factors affecting the oxidation efficiency of Sb(iii) and the enrichment performance of DLLME were investigated and optimized. The results showed that the proposed method exhibited good linearity (<i>R</i> ² = 0.9943), a low method detection limit (MDL = 0.3208 μg L^-1), and high precision (1.63%) and accuracy (0.64%) in the range of 1-30 μg L^-1, under the optimized process conditions. By the difference method, the trace free antimony (Sb(iii), Sb(v)) and total antimony (TSb) can be determined simultaneously.