This work describes designing and using a simple automated preconcentration system for estimation of tungsten in soil spectrophotometrically. The preconcentration of tungsten is based upon the retention of ion associate of [RB⁺.$\mathrm{H}{\mathrm{W}\mathrm{O}}_4^{-}$] inside a minicolumn packed with polyurethane foam. The retained ion associate is then automatically and quantitatively eluted by acetone. The tungsten concentration was estimated by measuring the absorbance of elution at 584 nm. The absorbance of elution follows Beer's law in concentration range of 0.5–100 µgL⁻¹ with a detection limit of 0.09 µgL⁻¹. The enhancement factor and relative standard deviation of proposed methodology were 50 and 1.7%, respectively. The system developed in this research is characterized by its low cost and high efficiency, as it uses low-cost PUF as a stationary phase and a few number of pumps and valves. On the other hand, the designed system can be used, in the future, with many detection techniques easily. The composition of the ion association formed between W(VI) ions and RB was calculated by continuous variation method (Job plot) to be 1:1 (W⁶⁺:RB). On the other hand, the ion associate in its solid state was synthesized and characterized using elemental analysis and ATR–FTIR technique. The retention of tungsten (VI) ions in the form of [RB⁺.$\mathrm{H}{\mathrm{W}\mathrm{O}}_4^{-}$] ion association on the surface of PUFs was confirmed by SEM images and XRF spectra. Moreover, the kinetic and thermodynamic behaviors of the retention of [RB⁺.$\mathrm{H}{\mathrm{W}\mathrm{O}}_4^{-}$] on the polyurethane foams were studied in detail. The kinetic models revealed that the retention of [RB⁺.$\mathrm{H}{\mathrm{W}\mathrm{O}}_4^{-}$] on PUF surface obeys the pseudo-second-order reaction. The thermodynamic investigations confirmed that the adsorption of [RB⁺.$\mathrm{H}{\mathrm{W}\mathrm{O}}_4^{-}$] on PUF surface was spontaneous at 298 K and the interaction between [RB⁺.$\mathrm{H}{\mathrm{W}\mathrm{O}}_4^{-}$] and active sites available on PUF surface was physical and electrostatic in nature.

这项工作描述了设计和使用一个简单的自动预浓缩系统，用于通过分光光度法估算土壤中的钨。钨的预浓缩是基于 [RB ⁺的离子缔合物的保留。$\mathrm{H}{\mathrm{宽}\mathrm{哦}}_4^{——}$] 在一个装有聚氨酯泡沫的微型柱内。然后，保留的离子缔合物会被丙酮自动定量洗脱。通过测量 584 nm 处洗脱的吸光度来估计钨浓度。洗脱吸光度遵循比尔定律，浓度范围为 0.5–100 µgL ^-1，检测限为 0.09 µgL ^-1. 所提出方法的增强因子和相对标准偏差分别为 50% 和 1.7%。本研究开发的系统具有低成本和高效率的特点，因为它使用低成本的 PUF 作为固定相和少量的泵和阀门。另一方面，设计的系统在未来可以很容易地与许多检测技术一起使用。W(VI) 离子与RB 之间形成的离子缔合的组成通过连续变化法（Job plot）计算为1:1 (W ⁶⁺ :RB)。另一方面，使用元素分析和 ATR-FTIR 技术合成并表征了固态离子缔合物。钨 (VI) 离子以 [RB ⁺ .$\mathrm{H}{\mathrm{宽}\mathrm{哦}}_4^{——}$] 通过 SEM 图像和 XRF 光谱证实了 PUF 表面上的离子缔合。此外，[RB ⁺ .$\mathrm{H}{\mathrm{宽}\mathrm{哦}}_4^{——}$] 对聚氨酯泡沫进行了详细研究。动力学模型显示 [RB ⁺ .$\mathrm{H}{\mathrm{宽}\mathrm{哦}}_4^{——}$] 在PUF 表面服从伪二级反应。热力学研究证实[RB ⁺ .$\mathrm{H}{\mathrm{宽}\mathrm{哦}}_4^{——}$] 在 PUF 表面上是自发的在 298 K 和 [RB ⁺ .$\mathrm{H}{\mathrm{宽}\mathrm{哦}}_4^{——}$] 并且 PUF 表面上可用的活性位点本质上是物理和静电的。