An in situ dispersive liquid–liquid microextraction (DLLME) method together with flame atomic absorption spectroscopy (FAAS) is developed for the extraction and determination of copper and cadmium from aqueous samples using as an extraction solvent a low cytotoxic ionic liquid (IL)-based surfactant, specifically decylguanidinium chloride (C₁₀Gu-Cl). The IL-based surfactant 1-hexadecyl-3-butylimidazolium bromide (C₁₆C₄Im-Br) is also used for comparative purposes. In the method, N,N′-bis(salicylidene)thiocarbohydrazide is the complexing agent, and the metathesis reaction in the in situ DLLME is accomplished using lithium bis[(trifluoromethyl)sulfonyl]imide. The main parameters affecting the extraction efficiency of the method, i.e. pH of the sample, NaCl content, and vortex time, are properly optimized with a Doehlert experimental design. The method using C₁₀Gu-Cl exhibited a limit of detection (LOD) four times lower and with slightly better reproducibility than that of the imidazolium IL-based surfactant. The validation of the in situ DLLME-FAAS method with C₁₀Gu-Cl is accomplished for the simultaneous extraction and quantification of copper and cadmium from water. The optimum method requires 10 mL of aqueous sample and ∼25 μL of the IL-based surfactant to obtain a microdroplet of ∼21 μL, which is diluted up to 120 μL with acetonitrile to perform the analytical determination of both metals. LODs down to 0.3 and 0.5 μg L⁻¹ were reached with the entire in situ IL-DLLME-FAAS for copper and cadmium, respectively. The inter-day relative standard deviation values were lower than 17% for both metal ions; with relative recoveries of 97.8% and 102%, and enrichment factors of 85 and 94, for copper and cadmium, respectively, at a low spiked level (4 and 6 μg L⁻¹, respectively). Furthermore, the developed method shows adequate precision and accuracy evaluated with a certified reference material, the absence of matrix effects, and high tolerance limits towards common cations (between 80 and 600) for the analysis of tap water, while accomplishing the requirements of green analytical chemistry.

中文翻译：

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胍盐离子液体基表面活性剂可作为适当的溶剂，使用原位分散液-液微萃取分离并预浓缩水中的镉和铜†

开发了一种原位分散液-液微萃取（DLLME）方法和火焰原子吸收光谱（FAAS）方法，以低细胞毒性离子液体（IL）为基础从含水样品中提取和测定铜和镉表面活性剂，特别是癸基胍氯化物（C ₁₀ Gu-Cl）。基于IL的表面活性剂溴化1-十六烷基-3-丁基咪唑鎓（C ₁₆ C ₄ Im-Br）也用于比较目的。在该方法中，N，N′-双（水杨基）硫代碳酰肼是络合剂，且易位反应发生在原位。DLLME使用双[（三氟甲基）磺酰基]酰亚胺锂完成。使用Doehlert实验设计适当优化了影响该方法提取效率的主要参数，即样品的pH值，NaCl含量和涡旋时间。使用C ₁₀ Gu-Cl的方法的检出限（LOD）较基于咪唑类IL的表面活性剂低四倍，并且重现性略好。用C ₁₀验证原位DLLME-FAAS方法Gu-Cl用于同时从水中萃取和定量铜和镉。最佳方法需要10 mL水性样品和约25μLIL基表面活性剂，以获得约21μL的微滴，然后用乙腈将其稀释至120μL，以进行两种金属的分析测定。整个原位IL-DLLME-FAAS的铜和镉的LOD分别达到0.3和0.5μgL ^-1。两种金属离子的日间相对标准偏差值均低于17％；在低加标水平（4和6μgL ^-1）下，铜和镉的相对回收率分别为97.8％和102％，富集因子分别为85和94， 分别）。此外，开发的方法显示出足够的精密度和准确度，并且使用了经过认证的参考材料，没有基体效应，并且对自来水的分析中常见的阳离子（80至600之间）具有较高的耐受极限，同时满足了绿色分析的要求。化学。