In this study, a novel magnetic bucky gel (MBG) was synthesized and coupled with dispersive magnetic solid-phase extraction for preconcentration and determination of trace levels of nitrite in various water samples. The MBG was prepared by dispersing magnetic graphitic carbon nitride nanocomposite (g-C₃N₄@Fe₃O₄) in a choline chloride-urea deep eutectic solvent (1:2, molar ratio). The deep eutectic solvent (DES) acts as a disperser and surface modifier for g-C₃N₄/Fe₃O₄ nanocomposites simultaneously and led to superior uptake of the analyte in a shorter time. The sorbent was characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The NO₂⁻ determination was carried out by UV-vis spectrophotometry. Variable factors on preconcentration of NO₂⁻ including pH, composition of MBG, contact time, sample volume, eluent type, eluent volume, and elution time were optimized. Under optimum condition, the limit of detection (LOD) was 1.56 μg L⁻¹, the linear dynamic range extended from 5.14 to 900.00 μg L⁻¹, the relative standard deviation (n = 5) and the preconcentration factor were 2.7% and 100, respectively. The method was successfully used for the preconcentration of NO₂⁻ ions in different water samples and gave recoveries between 89 and 103%.

中文翻译：

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使用深共晶溶剂基磁性巴基凝胶快速、环保地测定水中的亚硝酸盐

在这项研究中，合成了一种新型磁性巴基凝胶 (MBG)，并与分散磁性固相萃取相结合，用于预浓缩和测定各种水样中的痕量亚硝酸盐。MBG是通过将磁性石墨氮化碳纳米复合材料（gC ₃ N ₄ @Fe ₃ O ₄）分散在氯化胆碱-尿素深共熔溶剂（1:2，摩尔比）中制备的。低共熔溶剂 (DES) 作为 gC ₃ N ₄ /Fe ₃ O _{4的分散剂和表面改性剂}同时纳米复合材料，并在更短的时间内导致分析物的出色吸收。通过傅里叶变换红外 (FT-IR) 光谱、X 射线衍射 (XRD) 和场发射扫描电子显微镜 (FESEM) 对吸附剂进行了表征。NO ₂ ^-测定通过紫外-可见分光光度法进行。_{对 NO 2} ^-预浓缩的可变因素进行了优化，包括 pH、MBG 的组成、接触时间、样品体积、洗脱液类型、洗脱液体积和洗脱时间。最佳条件下，检测限（LOD）为1.56 μg L ^-1，线性动态范围从5.14扩展到900.00 μg L ^-1，相对标准偏差（n= 5) 和预浓缩因子分别为 2.7% 和 100。该方法成功地用于不同水样中 NO ₂ ^-离子的预浓缩，回收率在 89% 到 103% 之间。