DEVELOPMENT AND OPTIMIZATION OF A SPECTROPHOTOMETRIC METHOD WITH CLOUD POINT EXTRACTION FOR DETERMINATION OF GADOLINIUM

This work describes a simple, sensible, and low-cost analytical method, based on cloud-point extraction (CPE) of the surfactant (1,1,3,3-Tetramethylbutyl)phenyl-polyethylene glycol (Triton X-114), for the efficient extraction and sensible determination of gadolinium after its complexation with 1-(2-pyridylazo)-2-naphthol (PAN) and subsequent determination by ultraviolet-visible molecular absorption spectrophotometry at the wavelength of 556 nm. Full two-level and Doehlert experimental designs were applied to investigate and optimize the variables (pH, complexing concentration, and TX-114 concentration) involved in the extraction efficiency of Gd3+. The CPE was satisfactory for the determination of gadolinium with limits of detection (LoD) and quantification (LoQ) of 1.0 and 3.2 µg L-1, respectively, as well as an enrichment factor of 9.4. Accuracy was confirmed by spike tests with recovery values between 98.4 and 78.3%. The precision was expressed as relative standard deviation (%RSD, n =3), being found: 2.3% (10 µg L-1) and 2.7% (100 µg L-1). The proposed analytical method is suitable for the determination of Gd in tap water and contrast agent solutions.本研究报道了一种简便、灵敏且低成本的分析方法：基于表面活性剂（1,1,3,3-四甲基丁基）苯基聚乙二醇（Triton X-114）的浊点萃取（cloud-point extraction, CPE），先将钆与1-(2-吡啶偶氮)-2-萘酚（PAN）络合，随后在556 nm波长下采用紫外-可见分子吸收分光光度法进行灵敏测定，实现钆的高效萃取与定量分析。采用全二水平实验设计与Doehlert实验设计，对影响Gd³+萃取效率的关键变量（pH值、络合剂浓度、Triton X-114浓度）进行考察与优化。该浊点萃取方法用于钆的测定时性能优异，检出限（LoD）与定量限（LoQ）分别为1.0 µg L⁻¹和3.2 µg L⁻¹，富集因子达9.4。通过加标回收实验验证了方法的准确性，回收率介于78.3%~98.4%之间。以相对标准偏差（RSD%，n=3）表征方法精密度，结果显示：当钆浓度为10 µg L⁻¹时RSD为2.3%，浓度为100 µg L⁻¹时RSD为2.7%。本研究所提出的分析方法适用于自来水及造影剂溶液中钆的含量测定。