A paper-based method for heating preconcentration (PAD-HP) has been developed for the determination of Pb²⁺, Cd²⁺, Fe³⁺, and Ni²⁺. The design of our heating system was evaluated for dual quantification of ions using electrochemical and colorimetric methods simultaneously. The PAD-HP was used to detect Pb²⁺ and Cd²⁺ by anodic stripping voltammetry and to detect Fe³⁺ and Ni²⁺ by colorimetric reactions. Assay conditions were optimized by evaluating performance when changing the concentration of the colorimetric reagent, eluent volume, electrolyte concentration, and electrochemical parameters. Limits of detection (LOD) were determined to be 0.97 and 2.33 μg L^–1 for Pb²⁺ and Cd²⁺ (via voltammetry) and 0.03 and 0.04 mg L^–1 for Fe³⁺ and Ni²⁺ (via colorimetric assay), respectively. The relative standard deviations for assays were in the range of 5.76 to 10.12%. We observed that the PAD-HP method significantly enhanced the signal of all metals ions (14–100-fold, depending on the metal) in comparison to paper-based devices that did not use a heating preconcentration system. This PAD-HP method was successfully applied to the determination of metals ions in samples of drinking water, tap water, pond water, and wastewater. These results suggest that our approach can provide a convenient strategy to monitor aqueous samples for heavy metals with high sensitivity and selectivity.

中文翻译：

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使用电化学和比色法同时定量金属离子的双重样品预浓缩

开发了一种基于纸的加热预浓缩法 (PAD-HP)，用于测定 Pb ²⁺、Cd ²⁺、Fe ³⁺和 Ni ²⁺。我们对加热系统的设计进行了评估，以同时使用电化学和比色法对离子进行双重量化。PAD-HP用于通过阳极溶出伏安法检测Pb ²⁺和Cd ²⁺以及检测Fe ³⁺和Ni ²⁺通过比色反应。通过在改变比色试剂浓度、洗脱液体积、电解质浓度和电化学参数时评估性能来优化测定条件。Pb ²⁺和 Cd ²⁺的检测限 (LOD) 分别为 0.97 和 2.33 μg L ^–1 （通过伏安法）， Fe ³⁺和 Ni ²⁺的检测限为0.03 和 0.04 mg L ^–1（通过比色法），分别。测定的相对标准偏差在 5.76% 至 10.12% 的范围内。我们观察到，与不使用加热预浓缩系统的纸基设备相比，PAD-HP 方法显着增强了所有金属离子的信号（14-100 倍，取决于金属）。该PAD-HP方法成功应用于饮用水、自来水、池塘水和废水样品中金属离子的测定。这些结果表明，我们的方法可以提供一种方便的策略，以高灵敏度和选择性监测水样中的重金属。