This study proposes a method based on solid-phase extraction using a minicolumn with sugarcane bagasse for pre-concentration uranium in water samples. The first optimization step was used factorial design in two levels (2⁵) for the preliminary assessment of factors: elution flow, sample flow, pH, buffer concentration, and eluent concentration. From this design, it was found that all variables showed significant influence. In the second stage, using the Doehlert design with 5 variables, the optimal conditions were determined: pH 8.3, flow elution 5.5 mL min⁻¹, buffer concentration 0.045 mol L⁻¹, sample flow 5.5 mL L⁻¹, and eluent solution (ascorbic acid 0.6% w/v in medium of hydrochloric acid at a final concentration of 0.06 mol L⁻¹). The method was applied to the determination of uranium with a detection limit (LD) of 0.41 μg L⁻¹ and quantification (LOQ) of 1.40 μg L⁻¹, Relative standard deviation (RSD) 2.5 and 1.3% uranium concentration of 20 and 60 μg L⁻¹, respectively. The factor of pre-concentration for the system is 46 for a sample volume of 50 mL. The accuracy was confirmed by the spike test. The procedure was applied for the determination of uranium in tap water, well water, and human consumption; the samples were collected in the municipalities of Caetité, Cruz das Almas, Itabuna, Aramari-BA, and seawater samples from Todos os Santos Bay. Uranium concentrations were found in the analyzed samples varying from 7.0 to 16.5 μg L⁻¹.

中文翻译：

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甘蔗渣微柱法分离水样中铀的绿色分析方法

这项研究提出了一种基于固相萃取的方法，该方法使用带有甘蔗渣的微型柱对水中的铀进行预浓缩。第一步优化是在两个级别（2 ⁵）中使用因子设计进行因素的初步评估：洗脱流量，样品流量，pH，缓冲液浓度和洗脱液浓度。从该设计中，发现所有变量均显示出显着影响。在第二阶段中，使用具有5个变量的Doehlert设计，确定了最佳条件：pH 8.3，流速洗脱5.5 mL min ^-1，缓冲液浓度0.045 mol L ^-1，样品流速5.5 mL L ^-1和洗脱液（抗坏血酸0.6％w / v在盐酸介质中的终浓度为0.06 mol L ^-1）。该方法用于铀的检测限（LD）为0.41μgL ^-1，定量（LOQ）为1.40μgL ^-1，相对标准偏差（RSD）为2.5，铀浓度为20％和60％的1.3％微克L ^-1， 分别。对于50 mL的样品量，系统的预浓缩系数为46。准确度通过尖峰测试确认。该方法用于自来水，井水和人类消费中铀的测定。这些样品是在Caetité，Cruz das Almas，Itabuna，Aramari-BA的市政当局以及Todos os Santos湾的海水样品中收集的。分析样品中的铀浓度范围为7.0至16.5μgL ^-1。