Abstract

A highly sensitive, simple and safe method has been developed for the determination of trace palladium by cloud point extraction (CPE) combined with thermal lens spectrometry (TLS). The method is based on the fact that formation of the stable hydrophobic complex of palladium(II) with a newly synthesized reagent 2-(5-iodo-2-pyridylazo)-5-dimethylaminoaniline (5-I-PADMA), and then extraction into the micellar phase of non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114) as extracting agent at pH 4.8. Parameters that affect extraction efficiency, such as solution pH, concentration of 5-I-PADMA and Triton X-114, and equilibration temperature and time on CPE, were investigated and optimized. The results showed that an efficient extraction of palladium could be achieved with the following conditions were as follows: pH = 4.8 acetic acid-sodium acetate (HAc-NaAc) buffer solution, 100 μL 5 × 10^–4 mol/L 5-I-PADMA, 800 μL 1.0% (w/v) Triton X-114, and heat-assisted at 60°C for 20 min. After phase separation, the surfactant-rich phase containing palladium complex was dissolved in 450 μL 2 mol/L HClO₄-ethanol solution prior to its determination by TLS. A single mode He–Ne laser with 632.8 nm was employed for both excitation and probe beams. Under optimum experimental conditions, the calibration graph was linear over the range 0.1–7.5 ng/mL with a correlation coefficient of 0.9986. The detection limit was 1.0 ng/mL for palladium. The sensitivity enhanced by 558 times compared to that of the conventional spectrophotometry. The relative standard deviation (RSD) for elven replicate measurements of 1.0 ng/mL of palladium was 3.2%. The proposed method was applied to the determination of trace palladium in water samples.

中文翻译：

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浊点提取结合激光热透镜光谱法测定环境水样中痕量钯

摘要

建立了浊点萃取（CPE）结合热透镜光谱法（TLS）测定痕量钯的高灵敏度、简单、安全的方法。该方法是基于钯(II)与新合成的试剂2-(5-iodo-2-pyridylazo)-5-二甲基氨基苯胺(5-I-PADMA)形成稳定的疏水配合物，然后萃取进入非离子表面活性剂辛基苯氧基聚乙氧基乙醇 (Triton X-114) 作为萃取剂的胶束相，pH 为 4.8。研究和优化了影响萃取效率的参数，例如溶液 pH 值、5-I-PADMA 和 Triton X-114 的浓度以及 CPE 上的平衡温度和时间。结果表明，在以下条件下可以实现钯的有效提取：pH = 4。^–4 mol/L 5-I-PADMA，800 μL 1.0% (w/v) Triton X-114，在 60°C 下热辅助 20 分钟。相分离后，将富含表面活性剂的钯配合物相溶解在 450 μL 2 mol/L HClO _4中- TLS 测定前的乙醇溶液。激发光束和探测光束均采用 632.8 nm 的单模 He-Ne 激光器。在最佳实验条件下，校准图在 0.1–7.5 ng/mL 范围内呈线性，相关系数为 0.9986。钯的检测限为 1.0 ng/mL。与传统分光光度法相比，灵敏度提高了 558 倍。1.0 ng/mL 钯的精灵重复测量的相对标准偏差 (RSD) 为 3.2%。将所提出的方法应用于水样中痕量钯的测定。